US007 132060B2

(12) United States Patent (10) Patent No.: US 7,132,060 B2 Zagumennyi et al. (45) Date of Patent: Nov. 7, 2006

(54) SCINTILLATION SUBSTANCES (VARIANTS) (56) References Cited (75) Inventors: Alexander Iosifovich Zagumennyi, U.S. PATENT DOCUMENTS Moscow (RU); Yuri Dmitrievich 4,647,781 A 3/1987 Takagi ...... 250,361 R Zavartsev, Moscow (RU); Sergei 4,958,080 A 9, 1990 Melcher ...... 250/269 Alexandrovich Kutovoi, Moscow (RU) 4,988,882 A * 1/1991 Francois et al...... 250,483.1 5,660,627 A 8/1997 Manente et al...... 117, 12 (73) Assignee: Zecotek Medical Systems Inc. 6,278,832 B1 8/2001 Zagumennyi et al...... 385,141 (Continued) (*) Notice: Subject to any disclaimer, the term of this patent is extended or adjusted under 35 OTHER PUBLICATIONS U.S.C. 154(b) by 0 days. K.T. Wilke “A growing of crystals' Leningrad, publisher-Nedra>. (1977), 600p., a translation from Geramn von K. Th. Wilke (21) Appl. No.: 10/502,960 “KristallZuchtungen'

T, oc A. L '' ------N 1990 \ V V / \ ^ 1. -- y4-- - 1860 1840

< 100% lu03 44. 46 48 50 52 54 SiO2, mole US 7,132,060 B2 Page 2

U.S. PATENT DOCUMENTS A.M.Korovkin, T.I.Merkulyaeva, L.G.Morozova, I.A.Pechanskaya, M.V.Petrov, I.R.Savinova"Optical and spectral-luminescence prop 6,323,489 B1 1 1/2001 McClellan et al...... 250,361 R erties of the orthosilicate crystals of lanthanide' Optics and Spec 64 13,311 B1 7/2002 Melcher et al...... 117.13 6,437,336 B1 8, 2002 Pauwels et al...... 250,361 R troscopy, value 58, issue 6 (1985) p. 1266-1269.

6,464,777 B1 10/2002 Kitamura et al...... 117.13 I.A. Bondar, N.V. Vinogradova, L.N. Demyanets et al. “Silicates, 6,498,828 B1 12/2002 Jiang et al...... 250,483.1 germanates, phosphates, arsenates, and vanadates. Chemistry of rare 6,753,099 B1* 6/2004 Imamura et al...... 428,690 elements' monograph, Moscow, Nauka, (1983) 288 p. 2005/0173676 A1* 8/2005 Kurashige et al. .... 252/301.4 F The international X-ray library's database, PDF Database, Interna tional Center for Diffraction Data, Newton Square, PA, U.S.A. OTHER PUBLICATIONS R.L. Byer, J.F. Young “Growth of High-Quality LiNbO3 Crystals A.A. Vershman, K.I. Petrov, "A functional inorganic lithium com from the Congruent Melt” Journal of Appl. Phys. 41, N6, (1970), p. pound” Moscow, Energoizdat, (1996), 208p.* 2320-2325. P.I. Antonov, L.M. Zatulovski, A.S. Kostygov et al., “An obtaining P. Lerner, C. Legras, J. Dumas "Stoechiometrie des mohocristaux de of profiled single crystals and products by Stepanov's method”. metaniobate de lithium”, Journal of Crystal Growth, 3.4 (1968) p. Leningrad, “Nauka', (1981) p. 280.* 231-235. Carel W.E. van Eijk “Inorganic Scintillators in medical imaging P.V. Geld, F.A. Sidorenko "Dependence of physical-chemical prop detectors'. Nuclear Instruments and Methods in Physics Research A erties of non-stoichiometric compounds on structure of short-range 509 (2003) pp. 17-25. order Izvestia ANSSSR, seria Inorganic materials, v.15, #6, (1979) A.G. Gomes, A.Bril "Preparation and Cathodoluminescence of p. 1042-1048. Ce3+ activated yttrium silicates and some isostructural com pounds', Mat. Res. Bull. vol. 4, (1969) pp. 643-650. D.T.J. Hurle “Crystal Pulling from the Melt” Springer-Verlag, W. Rossner, R.Breu “Luminescence properties cerium-doped Berlin, Heidelberg, New-York, London, Paris, Tokyo, Hong Kong, gadolinium oxyorthosilicate cera-mics Scintillators' Proc. Int. Conf. Budapest, (1993) p. 21. on Inorganic Scintillators and Their Application, STINT’95, Neth C.D. Brandle, A.J. Valentino, G.W.Berkstresser “Czochralski erlands, Delft University, (1996) p. 376-379. growth of rare-earth orthosilicates (Ln2SiO5)”. J. Crystal Growth PDorenbost, C. van Eijekt, A.Bost, C.Melcher "Afterglow and 79 (1986), pp. 308-315. thermoluminescence properties of Lu2SiO5:Ce Scintillation crys E.G. Devitsin, V.A. Kozlov, S.Yu. Potashov, A.I.Zagumennyi, Yu.D. tals”, J.Phys.Condens. Matter 6 (1994), pp. 4167-4180. Zavartsev “Luminescent properties of Lu3Al5O12 crystal doped M.E. Globus, B.V. Grinev “Inorganic scintillators', publishing with Ce” Proceeding of International Conferences “Inorganic house AKTA Kharkov, (2000) p. 51. scintillators and their applications” (SCINT 95), Delft, the Nether W.M. Moses, S.E. Derenzo “Scintillators for positron emission lands, Aug. 20-Sep. 1. (1995). tomography”. Conference SCINT’95, Delft, The Netherlands (1995), LBL-37720. * cited by examiner U.S. Patent Nov. 7, 2006 Sheet 1 of 3 US 7,132,060 B2

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FIG. 1. U.S. Patent Nov. 7, 2006 Sheet 2 of 3 US 7,132,060 B2

Ll gj cN

2777-777/777-777/777-777 FIG. 3. U.S. Patent Nov. 7, 2006 Sheet 3 of 3 US 7,132,060 B2

324 a=116633 10 C-215811 0,9 605 0.8 0.7 304 0.6 0,5 0,4 210 400 412 O,3 421 214 336 0.2 401 330 511 110 OO6 Ey. 218 al 51C 433 0,1 1,107.2/E.301 311 4 s56. 32725512 602 435 15 18 21 24 27 30 33 36 39 42 45 48 51 54 57 60 20, degree

FIG. 4. US 7,132,060 B2 1. 2 SCINTILLATION SUBSTANCES (VARIANTS) transparent ceramics applicable for using in the medicine tomographs (U.S. Pat. No. 6,498,828 from Dec. 12, 2002). BACKGROUND OF THE INVENTION The drawback of patent proposed is a quality of Scintillation ceramics, which is made from, so-named, Stoichiometric The invention is applied to Scintilation materials and may 5 composition of lutetium oxyorthosi-licate mixture, a sto be used in nuclear physics, medicine, and oil industry for ichiometric composition is characterised by ratio of formula recording and measuring of X-ray, gamma- and alpha units of (Lu--Ce)/Si is equal exactly to 2/1. Since the radiation; non-destructive testing of Solid State structure; congruent composition of lutetium oxyorthosilicate does not three-dimensional positron-electron computer tomography coincide with Stoichiometric one, the ceramics of Stoichio (PET) and X-ray computer fluorography. The relevance of 10 metric composition apparently contains the components of the invention is that in fluoroscopy, X-ray computer tomog oxides which did not react completely as a results the raphy and PET, an introduction of new/improved scintilla scattering centers are formed. The light yield is an important tors has resulted in significant improvement of the image characteristic of a scintillator. The presence of Scattering quality or/and reduced the measuring time. (“Inorganic centers reduces a light yield appreci-ably. A transparent scintillators in medical imaging detectors' Carel W. E. van 15 ceramics made from a cerium-doped gadolinium oxyortho Eijk, Nuclear Instruments and Methods in Physics Research silicate has the same limi-tation (W. Rossner, R. Breu A 509 (2003) 17–25). “Luminescence properties cerium-doped gadolinium oxy The known Scintillation Substance is a lutetium oxyortho orthosilicate ceramics scintillators' Proc. Int. Conf. on Inor silicate powder doped with cerium LuosCeoloSiOs (A. G. ganic Scintillators and Their Application, STINT'95, Neth Gomes, A. Bril “Preparation and Cathodoluminescence of 20 erlands, Delft University, 1996, p. 376–379). The Ce" activated yttrium silicates and some isostructural com Scintilation elements fabricated from the transparent ceram pounds', Mat. Res. Bull. Vol. 4, 1969, pp. 643-650). This ics have the 60% less light yield than the elements fabricated phosphor was created for an application in the cathodolu from the Ce:GdSiOs crystals. minescence devices, however this Substance may be utilized Presence of an afterglow is very unwanted effect for some also for the X-ray, gamma- and alpha-ray emissions record- 25 applications, for example, for an imaging system, in which 1ng. the electronic part of device indicates a photon flux from the It is known the scintillation substance/crystal of cerium Scintilation elements absorbing the gamma radiation. The doped lutetium oxyorthosilicate CeLu-SiO5, where X afterglow effect, i.e. a photon flux from the scintillation is varied between the limits from 2x10 to 3x10° (U.S. Pat. element does not exposed to gamma radiation, reduces a No. 4,958,080, Sep. 18, 1990). The crystals of this compo- 30 contrast range, a sensitivity and a precision of device. The sition are grown from a melt having composition of Ce afterglow impairs also the parameters of medical devices Lu-SiOs. In scientific literature abbreviated name LSO: based on the utilization of positron emitting isotopes, for Ce is wide used for denotation of this crystal. The Ce, example, the three-dimensional medical tomographs (Fully Lu2SiO5 scintillation crystals have a number of advan 3D PET camera) for diagnostic of the cancer diseases, and, tages in comparison with other crystals: a high density, a 35 especially, for the MicroPET systems designed for testing of high atomic number, relatively low refractive index, a high the new medicines. A principle of operation of the three light yield, a short decay time of scintillation. The disad dimensional medical tomographs is that the microscopic vantage of known Scintillation material is the large spread of concentration of Substance containing an emitting positron important characteristics of Scintillation, namely, a light isotope is introduced into the blood of a patient. This yield and an energy resolution, from crystal to crystal. The 40 Substance is accumulated in the cancer cells of patient. An experimental results of systematic measurements of com emitted positron annihilates instantly with an electron this mercially produced LSO:Ce crystals grown by CTI Inc. results in the emission of the two 511 KeV energy gamma company (Knoxville, USA) clearly display this (U.S. Pat. quantums scattering exactly in opposite directions. In tomo No. 6,413.311, Jul. 2, 2002). Another disadvantage is a graph the detection of both gamma-quantums occurs by significant reduction of light yield, when the containing 45 means of the several ring detectors each of which contains LSO:Ce crystal device is operated under conditions when hundreds of the separate crystalline Scintilation elements. the temperature is above a room temperature, for example, The high Ce:LSO density gives an effective absorption of all in petroleum industry for the rock composition analyses in gamma quantums emitting from a body of patient examined. a borehole during the search of the new deposits. Another A location of the atom of a radioactive isotope in a patient disadvantage of LSO:Ce crystals is an afterglow effect, that 50 body is determined by means of a time detection of both is the prolonging fluorescence after radiation exposure, for gammas and numbers of Scintillation elements indicated example, the luminescence intensity of the samples these gamma quantums. In a patient body a part of gamma described in U.S. Pat. No. 4,958,080 is reduced to decibels quantums is scattered because of Compton effect, as a result, during ten minutes. the detection of gamma quantums occurs by the crystalline It is known the scintillation substance the lutetium oxy- 55 scintillation elements do not arranged in line. Therefore if an orthosilicate containing cerium, Ce:LuSiOs, in the form of Scintilation element has a strong afterglow then the indi a transparent ceramics. The LuSiOs: Ce Scintillator is cating system may recognise it as a result of annihilation at formed into ceramics material through sintering the a moment, however, actually, this detection is a consequence Lu SiOs:Ce powder. Because the LuSiOS:Ce has a mono of exposure to gamma quantum radiation in previous clinic structure rather than a cubic crystalline structure, the 60 moment of measuring. In the three-dimensional medical sintering produces a translucent ceramics rather than trans tomographs of regular resolution the several thousands parent. The cerium-doped lutetium orthosilicate is formed 6x6x30 mm scintillation elements are used, they maintain into a transparent glass Scintillator by combining the silicate the 6x6x6–216 mm volume three-dimensional resolution. oxide, lutetium oxide, cerium oxide, potassium oxide, and Even a strong afterglow of the Ce:LSO crystals does not lead barium oxide. The pores between the particles are removed 65 up to the considerable consequences when the compara which results in a consolidation of the scintillator material. tively thick 6x6 mm cross-section elements are used for a As a result, the translucent ceramics is converted into a diagnostics of the cancer illnesses, because a desired record US 7,132,060 B2 3 4 ing accuracy may be achieved by an injection of the large parameter was significantly better than for Ce:LSO crystals. doses of radioactive Substances or by a reducing of the rate However, the Lu. MeaSiO, crystals appreciably con of translation of patient through tomograph’s ring. ceded to the LuSiOs crystals in the basic scintillation However condition is changed sharply for MicroPET, parameters, namely, the light yield and density. Thus the which are used for a study of the life processes in vivo, lutetium oxyorthosilicate crystals, Ce:LSO, are a more pref especially, in a human brain or for a measuring of a erable scintillator for utilization in a three-dimensional distribution of medicines in a animal body (mouse, rats) positron-electron tomography, because a tomograph based during testing of the new medicines. For MicroPET systems on these crystals is a more sensitive and, in consequence, a it is necessary to use the devices with a maximal space dose of radioactive medicaments, adding in the blood of a resolution. The 1x1 mm sectioned and even 0.8x0.8 mm 10 patience on early stage of cancers, is reduced. sectioned scintilation elements are used just now. The 1 It is known the lithium containing Scintillation Substance mm space resolution is achieved. Because of So Small of the cerium doped yttrium silicate of chemical formula thickness of elements the numerous gamma quantums may LiHSiO, (M. E. Globus, B. V. Grinev “Inorganic scintilla cross direct the several scintillation elements at different tors', publishing house AKTA Kharkov, (2000) p. 51). The angles. Consequently, to calculate which part of a Scintilla 15 5%Ce"-doped LiYSiO, crystal has a peak of luminescence tion radiation is induced by Some or other gamma quantum at 410 nm, a luminescence time constant is equaled to 38 ns is a complicate technical task. In this case an afterglow and a maximal light yield at detection of gamma quantums becomes a very undesirable effect, because it reduces an is 1000 photons/Mev, this value is two and half time less accuracy all system. than for the known lutetium oxyorthosilicate Scintillating The afterglow and thermoluminescence phenomena are crystals, Cea, Lu2SiO5. A low efficient detection of explored circumstantially for the Ce:LSO crystals (P. Doren gamma radiation is resulted from a low density of Scintil bost, C. van Eijekt, A. Bost, Melcher “Afterglow and lator is equaled 3.8 g/cm. This substance may be utilized for thermoluminescence properties of Lu SiOs: Ce Scintillation detection of neutron radiation, however material is a low crystals”, J.Phys.Condens. Matter 6 (1994), pp. 4167–4180). efficient for a gamma radiation. According to this article an afterglow is observed both in the 25 It is known the lithium containing Scintillation Substance crystals having a high light yield and a low light yield, and of the cerium doped lutetium silicate of chemical formula a conclusion is that an afterglow is a property immanent to LiLuSiO, (M. E. Globus, B. V. Grinev “Inorganic scintil the Ce:LSO substance. lators', publishing house AKTA Kharkov, (2000) p. 51). It is known Substance the cerium doped gadolinium The 1%Ce"-doped LiLuSiO, crystal has a peak of lumi Oxyorthosilicate, CeeGd21-A2SiO5, where A is at least 30 nescence at 420 nm, a luminescence time constant is equaled one element selected from the group La (lanthanum) and Y to 42 nS and a maximal light yield at detection of gamma (yttrium), the X and y values are varied within the limits radiation is about 30000 photons/Mev, this value is 10% 0boule, decreasing to 30%-40% from a top to a 37720). This parameter is equaled 2.67 cm for crystal having bottom of a boule. Furthermore, a scintillation decay time (a 45 a density of 5.5 g/cm, whereas for the Ce2Lu21-SiOS time of luminescence) may be varied over the wide range of crystal of 7.4 g/cm density an attenuation length is equaled values from 29 nanoseconds to 46 nanoseconds, at that an 1.14 cm. energy resolution value may fluctuate within the 12%-20% The Ce:LiYSiO, and Ce:LillusiO crystals can not be limit. Such a large spread in performance leads up to recognised as a prototype for any variants of the given necessity during an industrial production to grow a large 50 invention, because they are differed both a chemical formula number of boules by Czochralski method, to cut them into and a crystal structure, which defines a crystal density. A parts (packs), to test each pack and on the basis of such tests high crystal density is a basic parameter for the applications to select the packs which possibly to utilize for fabrication which are the aim of the given invention. of Scintillation elements for medical tomographs. The chemical formulae of the given invention are the It is known the scintillation crystals, LU2-Me-SiO7. 55 numerous crystals of the solid solutions on the basis of the where LU is lutetium-based alloy which also includes one or silicate crystal containing a cerium, Ce, and crystallising in more of Sc, Yb, In, La, and Gd; where Me is Ce or cerium the monoclinic Syngony, spatial group B2/b, Z-4, and crys partially substituted with one or more of the elements of the tallising in a hexagonal Syngony of apatite structural type lanthanide family excluding lutetium; and where X is defined with a spatial group P6/m, Z=1. by the limiting level of LU substitution for Me in a mono 60 It is known the mono-cation cerium silicate crystallising clinic crystal of the lutetium pyrosilicate structure (U.S. Pat. in an apatite-brytolite structural type, CeoDog, (SiO4).O. No. 6,437.336). The crystal is formed by crystallization where O is a cation vacancy (A. M. Korovkin, T.I. Merku from a congruent molten composition of Lua-M2Si2O7. lyaeva, L. G. Morozova, I. A. Pechanskaya, M. V. Petrov, I. a congruent composition allows to use up to 80% of initial R. Savinova “Optical and spectral-luminescence properties melt, and the crystals exhibit reproducible scintillation 65 of the orthosilicate crystals of lanthanide' Optics and Spec response to gamma radiation, a light yield spread over troscopy, value 58, issue 6 (1985) p. 1266–1269) and the volume of boule did not exceed 20% and this commercial double silicate of cerium, LiCe(SiO4).O. (I. A. Bondar, N. US 7,132,060 B2 5 6 V. Vinogradova, L. N. Demyanets et al. “Silicates, ger mm. Another essential disadvantage of specified scintilla manates, phosphates, arsenates, and Vanadates. Chemistry of tion materials is the presence of oxygen vacancies which rare elements' monograph M. Nauka, (1983) 288 p.). A increase a light output and reduce a probability of cracking cerium presents in the Ceo Dog, SiO2 and LiCeoSiO2 of the boules at Sawing, however, simultaneously, the pres crystals, however, a luminescence is completely quenched in ence of oxygen vacancies in two-four times increases an them, this is explained by a concentration quenching in intensity of afterglow (thermoluminescence) after gamma consequence of high concentration of cerium ions in crys radiation of Scintillation material. tals. These crystals are not applicable for utilization as a Another confirmation of basic drawback of composition Scintillator. An analogue of the Substance claimed in the characterised by the 50%/LuO/50%SiO, molar ratio of items 16, 17, 18 of given invention is a crystal of mono 10 oxides is the information described in U.S. Pat. No. 5,660, cation cerium silicate, Ceos Dog, SiO2, since it has the 627. This patent protects a method of growing of lutetium same symmetry, P6/m, Z=1, and has a closest composition orthosilicate crystal with a plane front of crystallization by to the variants aforecited. An analogue of the Substance Czochralski method from a melt of Cea, Lu2SiOs chemi claimed in the items 19, 20, 21 of given invention is a crystal cal formula, where 2x10'> denotes any method of single crystal growth method, degradation of crystal quality despite on the extremely low including Czochralski method, Kyropoulas method, Bridg growth speed. A segregation coefficient of component is a man method and others known methods. ratio of component's quantity in a crystal to components The solutions of said tasks are achieved due to the use of quantity in a melt. Another common technical demerit of 50 Scintilation Substances both crystal and ceramics having the scintillation crystals on the base of lutetium orhtosilicate is compositions on the basis of ten variants of Substances the large losses of crystalline material because of cracking unified by the common structural types, the chemical for during slicing of a large, up to 60 mm in diameter, boules mulae and the method of fabrication of these materials. into 1 mm thickness pieces, which in their turn are cut into Variant #1. The known scintillation substance based on a rods to produce the 1x1x10 mm dimensions elements in the 55 silicate comprising a lutetium (Lu) and cerium (Ce), in the quantity of several tens of thousands pieces needed for first variant of given invention a new is a composition of assembling of one tomograph. substance is represented by the chemical formula BRIEF SUMMARY OF THE INVENTION Ce, Lu22-Si-Osy 60 X is a value between 1x10' fu. and 0.02 fu. A task of the given invention is a creation of a new y is a value between 0.024 fu. and 0.09 fu. Scintillation material and a method of its making. The given invention is directed on the solution of task of mass pro The technical result—the creation of scintillation substance duction of the large crystalline boules of scintillation mate having a large density; a high light yield and a homogeneity rials grown by directional crystallization method. Scintilla 65 of Scintillation properties during mass production is tion materials should have a large density; a highlight yield achieved due to the use of the substance based on a silicate and a homogeneity of Scintillation properties at mass pro having the congruent composition of basic components. US 7,132,060 B2 10 A technical result in the specific forms of implementation where A is at least one element selected from the group is achieved by way of using a Scintillation Substance, char consisting of Gd, Sc. Y. La, Eu, Tb, and Ca, acterised in that the composition of the substance in the form X is a value between 1x10' fu. and 0.02 fu. of a single crystal is represented by the chemical formula Z is a value between 1x10' fu. and 0.05 fu. In the specific forms of implementation the detailed Ce, Lu2.076 Slo.962O5.038, technical result, expressed in an increasing of a light yield X is a value between 1x10' fu. and 0.02 fu. following by an insignificant decrease of density is achieved Another technical result, namely mass production of large by the growing of a scintillation Substance, characterised in crystalline boules, having a high light output of a lumines that the composition of the Substance in the form of a single cence over all boule volume, a reproducibility of scintilla 10 is represented by the chemical formula tion properties of monocrystals, is achieved by method of making of Scintillating material. A single crystal is being CeLuz.076---La, Y, Slo.962O5.038: grown by a directional crystallization method from a melt X is a value between 1x10 fu. and 0.02 flu. made from the charge of the composition defined by the m is a value does not exceeding 0.05 flu. 51.9% (LuO +CeO)/48.1% SiO2 oxides mole ratio. 15 n is a value between 1x10' fu. and 2.0 fu. The particular specific forms of invention implementation Another technical result—mass production of large crys the technical result, expressed in a de-creasing of production talline boules, having a high light output of a luminescence cost of scintillation elements and a reproducibility of physi over all boule volume, a reproducibility of scintillation cal properties of the samples from boule to boule at mass properties of monocrystals grown during mass production, is production, is achieved by way of a growing of single crystal achieved by way of growing of Scintillating single crystal by of Czochralski method and a growing of crystal by a directional crystallization method from a melt made from Kyropoulas method. A new in the given method is the single the charge of the composition defined by mole ratio of crystal being grown by Czochralski method and also oxides 51.9% (LuO +AO+CeO)/48.1% SiO, where A Kyropoulas method from a melt made from the charge of the is at least one element selected from the group consisting of composition defined by the 51.9% (Lu,0+CeO)/48.1% 25 Gd, Sc., Y, La, Eu, and Tb. SiO=1.079 oxides mole ratio, this is, so named, a congru The particular specific forms of invention implementation ence composition. In that oxides ratio the composition of the technical result, expressed in a decreasing of production grown crystal is equaled to composition of a melt, this cost of Scintillation elements, reducing a crystal cracking circumstance allows to grow the crystals of more homoge during an after growth annealing and a cutting, and a neous in composition and in physical characteristics, than 30 reproducibility of physical properties of the samples from the crystals grown from a melt of Stoichiometric com boule to boule at mass production, is achieved by way of a position, 50% (LuO+CeO)/50% SiO-1. A growth of growing of single crystal of Czochralski method and a crystals from a melt of congruent composition allows to use growing of crystal by Kyropoulas method. A new in the more than 80% of melt, this appreciably cheapens a cost of given method is the single crystal being grown by Czochral Scintillation elements. 35 ski method and also by Kiropoulas method from a melt made Variant #2. The known scintillation substance based on a from the charge of the composition defined by mole ratio of silicate comprising a lutetium (Lu) and cerium (Ce), in the oxides 51.9% (Lu(O+AO,+CeO)/48.1% SiO, where A second variant of given invention a new is a composition of is at least one element selected from the group consisting of substance is represented by the chemical formula Gd, Sc., Y. Ta, Eu, Tb, and Ca. Ce, Lu2+2--A-Si-Osly 40 Variant #3. The known scintillation substance based on a silicate comprising a lutetium (Lu) and cerium (Ce), in the where A is at least one element selected from the group third variant of given invention a new is a Substance con consisting of Gd. Sc. Y. La, Eu, Tb, and Ca, taining a lithium, Li, in the quantity does not exceeding 0.25 X is a value between 1x10' fu. and 0.02 fu. fu., and the composition of Substance is represented by the y is a value between 0.024 fu. and 0.09 fu. 45 chemical formula Z is a value between 1x10 fu. and 0.05 fu. CeLateLuz-e 2-Si-Osly-p The technical result—the creation of scintillation substance X is a value between 1x10' fu. and 0.02 fu. having a comparatively low cost, a high light yield and a y is a value between 0.024 fu. and 0.09 fu. homogeneity of Scintilation properties, is achieved due to 50 q is a value between 1x10' fu. and 0.02 fu. the use of the Substance based on a silicate having the congruent composition of total basic components, (Lu--A+ p is a value between 1x10 fu. and 0.05 fu. Ce) and Si. The substitution of heavy expensive lutetium for The technical result—the creation of scintillation substance at least one comparatively light element selected from the having a high light yield, a large density, a homogeneity and Gd, Sc., Y. La, Eu, Tb, and Ca group reduces a manufactory reproducibility of Scintillation properties during mass pro cost, reduces a crystal cracking during an after growth 55 duction is achieved due to the use of Substance based on a annealing and a cutting, increases a light yield, but may silicate containing lithium and having the congruent com cause an inconsiderable decreasing the density. The cheap position of the basic components. Scintillation crystals having a smaller density of 7.2-7.4 A technical result in the specific forms of implementation, g/cm, and atomic number of Z=58–63, but a highlight yield expressed in a decreasing of production cost of Scintillation are useful for numerous applications, for example, in nuclear 60 elements and a reproducibility of physical properties of the industry. samples from boule to boule at mass production, is achieved A technical result in the specific forms of implementation due to the use of the scintillation substance is characterised is achieved by way of using a Scintillation Substance, char in that the composition of the substance in the form of a acterised in that the composition of the substance in the form single crystal containing a lithium Li in the quantity does not of a single crystal is represented by the chemical formula 65 exceeding 0.25 flu. is represented by the chemical formula Ce, Lu2O76--A-Slo.962O5.038, CeLateLuz.076 p-Slo.962O5.038 p. US 7,132,060 B2 11 12 X is a value between 1x10' fu. and 0.02 fu. fifth variant of given invention a new is a composition of q is a value between 1x10" fu. and 0.2 fu. substance represented by the chemical formula p is a value between 1x10' fu. and 0.05 fu. Another technical result—mass production of large crys talline boules, having a high light output of a luminescence 5 X is a value between 1x10' fu. and 0.1 fu. over all boule volume, a reproducibility of scintillation The technical result—the creation of scintillation substance properties of monocrystals grown during mass production, is having a large density; a high light yield is achieved due to achieved by way of growing of Scintillating single crystal the making of the mono-cation silicate crystallized in a grown by a directional crystallization method from a melt hexagonal Syngony of apatite spatial group P63/m. Z=1, as made from the charge of the composition defined by mole 10 well as the expense of an advantageous content of Ce" ions ratio of oxides 51.9% (LuC+LiO+CeO)/48.1% SiO. in the Substance. Variant #4. The known scintillation substance based on a Variant #6. The known scintillation substance based on a silicate comprising a lutetium (Lu) and cerium (Ce), in the silicate comprising a lutetium (Lu) and cerium (Ce), in the fourth variant of given invention a new is a Substance sixth variant of given invention a new is a Substance containing a lithium, Li, in the quantity does not exceeding 15 containing a lithium, Li, and the composition of Substance is 0.25 flu., and its composition is represented by the chemical represented by the chemical formula formula CeLateLllo.33--Do.67Si6O26 p. CeLateLu2-p2---A-Si-Os: p. X is a value between 1x10 fu. and 0.1 fu. where A is at least one element selected from the group q is a value between 1x10' fu. and 0.3 fu. consisting of Gd. Sc, Y. La, Eu, and Tb. p is a value between 1x10 fu. and 0.25 flu. X is a value between 1x10' fu. and 0.02 fu. The technical result—the creation of scintillation substance y is a value between 0.024 fu. and 0.09 fu. having a large density; a high light yield is achieved due to Z is a value between 1x10 fu. and 0.05 fu. the making of the mono-cation silicate crystallized in a q is a value between 1x10' fu. and 0.2 fu. 25 hexagonal Syngony of apatite spatial group P63/m. Z=1, as p is a value between 1x10 fu. and 0.05 fu. well as the expense of an advantageous content of Ce" ions in the Substance. The technical result—the creation of scintillation substance Variant #7. The known scintillation substance based on a having a comparatively low cost, reducing a crystal cracking silicate comprising a lutetium (Lu) and cerium (Ce), in the during an after growth annealing and a cutting, a high light 30 seventh variant of given invention a new is a Substance yield and a homogeneity of Scintillation properties, is containing a lithium, Li, and the composition of substance is achieved due to the use of the substance based on a silicate represented by the chemical formula having the congruent composition of the total basic com ponents, (Lu--Li+A+Ce) and Si. The substitution of heavy CeLateLllo.33-x-p-z 0.67A-Sisozge expensive lutetium for at least one comparatively light 35 element selected from the Gd, Sc. Y. La, Eu, and Tb group where A is at least one element selected from the group reduces a manufactory cost, increases a light yield, but may consisting of Gd. Sc, Y. La, Eu, and Tb, cause an inconsiderable decreasing of density. The cheap X is a value between 1x10' fu. and 0.1 fu. Scintillation crystals having a smaller density of 7.2-7.4 q is a value between 1x10' fu. and 0.3 flu. g/cm, and atomic number of Z=58–63, but a highlight yield 40 p is a value between 1x10' fu. and 0.25 fu. are useful for numerous applications, for example, in nuclear Z is a value between 5x10' fu. and 8.9 fu. industry. The technical result—the creation of scintillation substance A technical result in the specific forms of implementation having a large density, reducing a crystal cracking during an is achieved by way of using a Scintillation Substance, char after growth annealing and a cutting, a high light yield is acterised in that the composition of the substance in the form 45 achieved due to the making of the mono-cation silicate of a single crystal containing a lithium Li in the quantity crystallized in a hexagonal Syngony of apatite spatial group does not exceeding 0.25 ful. is represented by the chemical P6/m, Z=1, as well as the expense of an advantageous formula content of Ce" ions in the substance. Variant #8. The known scintillation substance based on a CeLateLu2.076 ex-A-Slo.962O5.038 p. 50 silicate comprising a lutetium (Lu) and cerium (Ce), in the where A is at least one element selected from the group eighth variant of given invention a new is a Substance consisting of Gd. Sc, Y. La, Eu, and Tb, containing a lithium, Li, in the quantity one formula units X is a value between 1x10' fu. and 0.02 fu. and the composition of Substance is represented by the chemical formula Z is a value between 1x10 fu. and 0.05 fu. 55 q is a value between 1x10" fu. and 0.2 fu. Ce, LiLug Si6O26, p is a value between 1x10' fu. and 0.05 fu. Another technical result—mass production of large crys X is a value between 1x10' fu. and 0.1 fu. talline boules, having a low cost, a high light output of a The technical result—the creation of scintillation substance luminescence over all boule volume, a reproducibility of 60 having a large density; a high light yield is achieved due to Scintillation properties of monocrystals grown during mass the making of the double silicate crystallized in a hexagonal production, is achieved by way of growing a single crystal Syngony of apatite spatial group P63/m, Z=1, as well as the by a directional crystallization method from a melt made expense of an advantageous content of Ce" ions in the from the charge of the composition defined by mole ratio of Substance. oxides 51.9% (LuC+LiO+AO+CeO)/48.1% SiO. 65 Variant #9. The known scintillation substance based on a Variant #5. The known scintillation substance based on a silicate comprising a lutetium (Lu) and cerium (Ce), in the silicate comprising a lutetium (Lu) and cerium (Ce), in the ninth variant of given invention a new is a Substance US 7,132,060 B2 13 14 containing a lithium, Li, in the quantity exceeding 1.0 ful. For practical applications the crystals having the higher and the composition of Substance is represented by the cerium ions concentration are required because Such crystals chemical formula have appreciably higher light yield. However, the very high CeLiliateLug--SeO26 p. cerium concentration leads to the several negative results. Firstly, the crystals with a high cerium concentration have a X is a value between 1x10' fu. and 0.1 flu. bad optical quality, the scattering centers are presented in q is a value between 1x10' fu. and 0.3 fu. crystals. Secondly, a reducing of light yield is taken place p is a value between 1x10' fu. and 0.25 flu. because of both a lowering of optical quality and a decreas The technical result—the creation of scintillation substance ing of quantum efficiency, which happens due to an inter having a large density; a high light yield is achieved due to 10 action of neighbour cerium ions, so named, an effect of the making of the double silicate crystallized in a hexagonal concentration quenching of luminescence. Therefore the Syngony of apatite spatial group P63/m, Z-1, as well as the upper limit for cerium ions is set 0.02 f. units for all expense of an advantageous content of Ce" ions in the Substances of given invention, which are crystallized in a Substance. monoclinic syngony, at the structural type Ce, Ln2SiOs Variant #10. The known scintillation substance based on 15 with a spatial group B2/b, Z=4. The upper limit of 0.1 f. units a silicate comprising a lutetium (Lu) and cerium (Ce), in the is set for the Ce, Lnossog, SiO2 and Ce, LiLn3SiO2 tenth variant of given invention a new is a Substance Substances being crystallized in a hexagonal Syngony, an containing a lithium, Li, in the quantity exceeding 1.0 ful. apatite structural type with a spatial group P63/m. Z=1. and the composition of Substance is represented by the These limits are defined by experimentally. When the con chemical formula centration is above indicated limits, then the formation of numerous scattering centers of light takes place during Ce, Lila Lug---A-SigC26 p. crystallization and, therefore, the implementation of Such defective crystals in medical and technical devices is not where A is at least one element selected from the group possible. consisting of Gd. Sc, Y. La, Eu, and Tb, 25 The technical result, namely a production of large crys X is a value between 1x10' fu. and 0.1 flu. talline boules, having a high light output of a luminescence q is a value between 1x10' fu. and 0.3 fu. over all volume, a reproducibility of scintillation properties p is a value between 1x10' fu. and 0.25 flu. of monocrystals grown at mass production, a small percent Z is a value between 5x10 fu. and 8.9 fu. of losses of valuable scintillation elements because of crack The technical result—the creation of scintillation substance 30 ing during sawing and manufacturing of Scintillation ele having a large density, reducing a crystal cracking during an ments, is achieved due to the growing of Scintillation crys after growth annealing and a cutting, a high light yield is tals of congruency composition. The common improvement achieved due to the making of the double silicate crystal sign for the variants #1, #2, #3 and #4 is a value of ratio of lized in a hexagonal Syngony of apatite spatial group P63/m. rare-earth ions and silicon ions in chemical composition of Z=1, as well as the expense of an advantageous content of 35 Substance, i.e. a composition characterized by a ratio of Ce" ions in the substance. formula units of (Lu 2-2+Ce,)/Sil- and (Lu,+Ce, + For all enumerated variants the presence of cerium ions, A)/Si is differed from a 2/1 ratio which is obligatory Ce", is a mandatory requirement, because a scintillation exactly equaled to 2 for all known Scintillation Substances on under gamma and X-ray radiation combines with lumines the basis of orthosilicates. For the substances of given cence originating from the Ce" ion 5d->F transfer. For 40 invention the ratios of formula units of (Lu 2+Ce,)/Si all variants of substances the maximum of Ce" ion lumi and (Lu 2-2 --Ce,+A)/Si are varied within the limit nescence is in the blue 410–450 nm region of spectrum. This from 2.077 to 2.396 that corresponds to the mole oxides ratio band is an optimal for detection of radiation with both the equaled to 51.2%(LuO +CeO+AO)/48.8%SiO=1.049 photomultiplier tubes and semiconductor radiation detec and 54.5%(LuO +CeO+AO)/45.5%SiO=1.198. tors. For measurements in that region the ordinary, commer 45 respectively. These magnitudes correspond to the composi cial photomultiplier tubes having inexpensive glass input tions of Substances Ce, Lu 22-Si-Os. Ce, Lu22--- window are used, this reduces the cost of medical devices in A-Si-Os, Ce, Li Lu 22---A-Si-Os, where comparison with devices in which the Scintillation crystals, variable y is changed within the limits from 0.024 f. units to having an emission peak in ultraviolet region of spectrum, 0.09 f. units. We have measured specified magnitude using are utilized. A high quantum yield of cerium ions lumines 50 the commercial device for the electronic microanalysis cence is also the representative indication of all crystals (Cameca Camebax SX-50, operating at 20 kV, 50 mA and having the above-mentioned chemical formulas. The diameter of the beam of 10 microns), an accuracy of 5%–9% quantum yield characterizes which part of gamma measurements of composition was +0.003 f. units, in mole quantum energy is converted into Ce" ions emission, and percents an accuracy was iO.15 mol%. The mechanically which part of energy (91%-95%)) is dissipated at thermal 55 polished samples for measurements were cut from the oscillations of lattice atoms. An essential Scintillation crystals grown by directional crystallization method from parameter, a light yield depends directly on concentration of the melts having the mole ratios of components (Lu + cerium, Ce", ions in a substance/crystal. Ce)/Si and (Lu --Ce+A)/Siwithin the limits from 1.77 For all variants the lower limit for the cerium ions is to 2.44. On the basis of X-ray phase analysis and measure determined by the fact that at the content of Ce" in the 60 ments of melting point of series of powdered compositions, quantity of less than 1x10" f. units, the effectiveness of a the authors of the given invention have defined the part of scintillation luminescence of Ce" becomes insignificant phase diagram for region of existence of lutetium oxyortho because of the small concentration. With the concentration silicate in the Lu(O. SiO, system (FIG. 1). The process of of cerium lower than the above limit, the implementation of changing of composition of Solid solutions of lutetium the technical task cannot be reached, namely it is not 65 oxyorthosilicate crystals (phase “S”) in depending on a possible to achieve a light yield sufficient for practical composition of melt is exhibited on FIG. 1. In accordance utilization. with the traditional notations, a liquid phase is symbolized US 7,132,060 B2 15 16 by 'L' on this diagram. The maximum of melting point relative to a lutetium is determined by the oxides mole ratio temperature of solid solutions “S” corresponds to the com of 51.2% (LuC+CeO)/48.8% SiO =1.049, which corre position of 51.9 mol %LuO +48.1 mol %SiO on consti sponds to the value of variable y=0.024 in a chemical tution diagram. The region of existence of phase “S” is formula of scintillation substance. The lower boundary is surrounding by the fields of two-phase equilibrium L+S, determined by an accuracy of the chemical and physical LuO +S and S--LuSi2O7. experimental methods of measurements of lutetium and The phase diagram (FIG. 1) was detailed for the near silicon in a crystal. Such accuracy allows in a unique manner equilibrium conditions of Solidification during crystal grow to distinguish the Substances/crystals chemical compositions ing from the melts having the different chemical composi of the given invention from the compositions of known tions. The comparison of composition of initial melt with the 10 lutetium orthosilicate scintillation crystals having the 50% composition of crystal grown from that melt determines that (Lu O+CeO)/50% SiO, mole ratio of components. a Solidification occurs in accordance with a liquidus and a The upper boundary of a components content in a crystal solidus lines shown on FIG. 1. The compositions of melts relative to a lutetium is determined by the oxides mole ratio have been set at weighing of the initial chemicals, the of 54.5% (LuO +CeO)/45.5%SiO-1. 198, which corre temperatures of melts also were taking in account during 15 sponds to the value of variable y=0.09 in a chemical formula experiments. The crystals growing were carried out at the of scintillation substance. This boundary is determined conditions of low gradients of temperature and with the experimentally. In a case of further increasing of a LuO crystals pulling rates near 0.3 mm/hour, that maintained an content in an initial melt and, consequently, in a crystal the attaining of the effective segregation coefficients of the Lu" scattering centers are occurred, that decreases a light yield, and Si" ions between a melt and a growing crystal at the and, as a result, a technical result of given invention cannot conditions near to equilibrium. be reached. After conversion of the values of compositions The liquidus and solidus lines on FIG. 1 show, that the of the lower and upper boundaries into formula units for the lutetium oxyorthosilicate crystals may have the composi #1, #2, #3 and #4 variants, the range of compositions in tions characterized by the different ratio of initial LuO and formula units defined by the ratios of (Lu +Ce)/Si and SiO2 oxides, namely, a content of chemicals is within the 25 (Lu +Ce+A)/Si is lying within the limit from 2.077 to range the 44.5-50.5 mol % for SiO, and the 55.5–49.5 mol 2.396. These values correspond to the compositions % for Lu-O. However, for the practical purposes the described by the chemical formulae Ce, Lu22-Si-Os. specified range of compositions is interested only partially, Ce, Lu22---A-Si-Os, and Li Ce, Lu22---A-Si three compositions of melt denoted by the arrows numbered Os, where y varies between the limits from 0.024 f. unites 1, 2, and 3 illustrate this. The arrow 1 denotes the 50% 30 to 0.09 f. units. LuO +50% SiO, composition of initial melt. It should be Should make a point of the compositions of lutetium pointed out that the composition of crystal growing from this oxyorthosilicate solid solutions crystals, i.e. the composi melt has the ratio of basic components less than 50.9 mol % tions, which are to the right side from the maximum of their Lu-O/49.1 mol % SiO-1037. To grow the crystal of maximal melting point, FIG.1. This is a region of the crystal composition having the ratio of basic components equaled 35 compositions lying to the right side bounded by a maximal exactly to 50 mol% LuO/50 mol % SiO =1, it is required SiO2 solubility, corresponds to a solid solution composition to use a melt of composition denoted by arrow 2, i.e. the having a molar ratio of 49.5% LuO/50.5% SiO, 0.980, ratio of basic components in the melt is approximately and a left boundary of crystal composition having the value equaled to 46 mol % LuO +54 mol % SiO=0.852. of 50.9% LuO/49.1% SiO =1.037, is determined by the An optimal composition of oxides mixture (a charge) for 40 50% LuO +50% SiO, composition of melt, FIG. 1. the growth of Scintillation crystal of high quality in the Let us determine the crystals of which compositions may conditions of the low temperature gradients (a large diam grow by a directional crystallization method from a melt eter of crucible) is the composition denoted by arrow 3. In obtained from a charge of the Stoichiometric composition, this case the segregation coefficients of basic components 50% LuO/50% SiO=1.000, denoted by the arrow 1 on are equaled to a unity, and a composition of charge of melt 45 FIG. 1. Depending on the technology peculiarities, namely coincides with the composition of growing crystal, both the thermal conditions of a growing, the temperature gradi composition of charge and composition of grown crystal ents on a melt-crystal interface determining by a crystal have the contents of basic components characterized by the diameter, the components segregation coefficients may vary mole ratio of 51.9% Lu(O+48.1% SiO-1079. from 1 to the equilibrium values which in its turn are Therefore, FIG. 1 shows the unique solution of technical 50 determined in accordance with the constitution diagram task in the specific forms of implementations of first, second, FIG. 1. As a result, from a charge of the stoichiometric third, and fourth variants describing the scintillation sub composition of 50% LuO +50% SiO, may grow the crys stances for the growing of oversize single crystals by tals of compositions being in the range bounded by the lower Kyropoulos method, and also for the growing of big single limit of a component ratio of more than 49.5% LuO/50.5% crystals by Czochralski method utilizing the optimal com 55 SiO=0.980, and the upper limit of a component ratio of less, position of initial oxides having the mole ratio of 51.9% than 50.9% LuO/49.1% SiO-1037. In formula units this (Lu 20+CeO)/48.1% SiO, and the compositions of corresponds to the values range in which the variable y is charge of melt and grown crystals coincide and are described more than (-0.01)+0.003 f. units, but less than 0.018+0.003 by the chemical formula f. units. The given range of the crystal compositions has not 60 been patented in the known patents. However the given Ce, Lu2.076 Slo.962O5.038 range cannot be a subject of new invention because the crystals having a composition in the given range are covered where x is a value between 1x10 fu. by a concept of existing state of the arts. These crystals do The evidence of choice of the lower and upper values of not maintain an improvement of technical performance in the ratios range of the initial LuO and SiO2 oxides for the 65 comparison with the known Substances. A growing of a substances of variants #1, #2, #3 and #4 is illustrated on FIG. lutetium oxyorthosilicate crystal of high quality requires to 1. The lower limit of a components content in a crystal use the congruent composition of melt, which appreciably US 7,132,060 B2 17 18 differs from the composition of crystal growing from this (Lu O+LiO+CeO)/48.1% SiO, for variant #3 and the melt. The crystals grown from a melt of stoichiometric 51.9% (Lu(O+LiO+AO+CeO)/48.1% SiO, for variant composition have an appreciable variation of chemical com H4./ position along a length, and also an extremely large variation The specific peculiarities and the growth parameters of of all physical and Scintillation parameters both along the 5 rare-earth silicates of stoichiometric composition for a direc length and diameter because the segregation coefficients of tional crystallization method, in particular for Czochralski silicon and lutetium are differed from 1. Such crystals are method are presented in article (C. D. Brandle, A. J. Valen utilized for the scientific researches, however a commercial tino, G. W. Berkstresser “Czochralski growth of rare-earth production of crystals having a similar composition are of no orthosilicates (Ln-SiOs), J. Crystal Growth 79 (1986), pp. 10 308-315). In this paper a ratio of crystal diameter (d) to a interest because the percent of a chemical oxides-to-scintil crucible diameter (D) has a magnituded/D-0.4, which is an lation element yield is a low, a manufacturing cost is an optimal value for Czochralski method. A condition of opti extremely high. mal dimensions of crucible for Czochralski method is a In the specific forms of implementation the scintillation crucible height (H) is equaled to its diameter, D=H. substances claimed in variants from the first to the fourth 15 The low temperature gradients are a key peculiarity of inclusive are achieved in the forms both a polycrystal/ large (80 mm-150 mm in diameter) crystals growing by a ceramics and a single crystal. directional crystallization method, in particular Kyropoulos The manner of ceramics making by the method of hot method from the iridium crucibles of 100 mm-180 mm in pressing, for example, the Gd2O(SiO4):Ce Scintillation diameter, and an optimal ratio of a crystal diameter to a ceramics is described, for example, in the paper (W. Rossner, crucible diameter is d/D=0.7–0.9. Kyropoulos method is R. Breu “Luminescence properties cerium-doped gado widely utilized for a commercial production of massive linium oxyorthosilicate ceramics scintillators' Proc. Int. Sapphire crystals (Al2O), and for Some alkali-halide scin Conf. on Inorganic Scintillators and Their Application, tillation crystals also. However, the authors of given inven STINT95, Netherlands, Delft University, 1996, p. tion do not know publications about a growing of rare-earth 25 silicates by Kyropoulos method. A technique and the 376–379). In another manner of fabrication of high optical attributes of Kyropoulos method and Czochralski method quality ceramics-Scintillator the water solutions of are described in detail in the book (K. T. Wilke “A growing Lu–Ce—A chlorides, where A is at least one of the ele of crystals' Leningrad, publisher ingot-to-scintillation element melt in crucible (H), a crystal diameter (d) and length of high product yield (no cracks); a saving up to 20%–50% of cylindrical part of a crystal (h) are given by the relations: Scintillation Substance because of elimination of cutting from technology of fabrication of fine-face scintillation elements; a uniform distribution of cerium Ce ions in a 55 polycrystalline body; a shortening of Scintillation elements where y-0.1 D; (d/D)-0.7+0.9; H-(d/D) h. processing time; any desirable shaping of Scintillation ele At the optimal ratio (d/D)-0.8 a grown crystal is placed mentS. within a crucible during cooling, that is an important con In the specific forms of implementation a method of dition for uniform decreasing of temperature over boule directional crystallization is used to make a Scintillation 60 Volume during an after-growth annealing. Such placement Substance in the form of single crystal. A new in a proposed of a crystal relative to a crucible is a principal difference method is that a single crystals are being grown by a between Kyropoulos method and Czochralski method, in directional crystallization method from the melts made from which a grown crystal is placed above the crucible after the congruent composition charges, the compositions are breaking away of melt to start an annealing process. A characterised by the oxides mole ratio of 51.9% (LuO + 65 different position of crystal relative to crucible in Czochral CeO)/48.1% SiO, for the variant #1, the 51.9% (LuO + ski method results in the conditions under which a top of AO+CeO)/48.1% SiO, for the variant #2, the 51.9% grown boule has an appreciably lower temperature than a US 7,132,060 B2 19 20 bottom placed near a hot crucible. This circumstance leads and the experimental data, the range of variable Z is chosen to a different content of oxygen vacancies and to a different between 1x10" f. units and 0.05 f. units for the variants of Ce"/Ce" ions ratio through the full crystal length, this is an the Substances Ce, Lu22-A-Si-Os, and Ce, Li additional cause of a strong spread of parameters from boule Lu2-2-A-Si-Os, where A is at least one elements to boule grown by Czochralski method of the scintillating 5 of the group Gd, Sc, Y. La, Eu, and Tb. However, this range lutetium oxyorthosilicate crystals. All boules grown by may be extended appreciably for the Yand La elements, for Czochralski method have some differences of properties which an enlarged light yield is maintained even at the high through the crystal length and its diameter, and in combi concentrations while the crystal density is decreasing. Thus nation with annealing under the heavy temperature gradients a technical result in the specific forms of implementations is this results in the considerable spread of parameters of 10 achieved due to a growing of Scintillation Substance of scintillation elements fabricated from the different parts of CeLu2.076---La, Y,Sio962Ososs, in which the Value of boule. Contrariwise, the low temperatures gradients in a variable m does not exceed 0.05 f. units, and the range of crystal during annealing process are achieved if a boule is variable n is between 1x10' f. units and 2 f. units. placed within a crucible, as FIG. 2 and FIG.3 demonstrates. For the substances of the #6 and #10 variants having the Practically such method of fabrication allows to cool the 15 chemical formulae Ce, Li Luoss---- loo7A-SiO26. crystals in the near isothermal conditions. This is a basis to and Ce, Lil Luo----A SiO26 P accordingly, a range achieve an invariability of light yield from the different parts for variable Z is set between 1x10" f. units and 8.9 f. units. of a large Kyropoulos grown crystal. To maintain a large density and a high light yield the Small In the scintillation substance described in the variants #2, concentrations are preferable as said the above. Neverthe #4, #7 and #10 an isomorphic substitution of the lutetium less, an upper limit is set at 8.9 f. units, in this case the ions for at least one of the ions of the group Gd, Sc. Y. La, crystals have a low density and a comparatively small light Eu, and Tb, is possibly, at that a substitution may be fulfilled yield with a sharp decreasing of an initial chemicals cost at a more wide range than it is claimed in the given and, therefore, a crystal cost. Such crystals may be interest invention. However a conceptual drawback of considerable for utilization as the sensors in the atomic power plants for widening of a lutetium ions Substitution range is a decrease 25 which the important parameters are a high radioresistance of crystal density and, consequently, a sharp decrease of and chemical resistance in the compatibility with a low cost. efficiency of gamma-quantums absorption that results in a The similar sensors should be in every room of plant to decreasing of light yield. Besides, the Eu and Tb ions measure a radiation level without presence of human. The decrease the luminescence intensity in the blue region of existent sensors on the basis of alkali-halide crystals are spectrum because a part of energy due to the redistribution 30 unreliable because they cannot operate in a high radiation emits in a red region of spectrum at europium Substitution level possible in case of the emergencies. and emits in a green region of spectrum at terbium substi For the #3 and #4 variants of scintillation Substance on the tution. In a case of the properly chosen concentrations of the basis of lutetium silicate, a common distinctive feature is a cerium, terbium, and europium ions a Scintillation crystal presence of the lithium ions in the quantity does not exceed emits a white light, i.e. all visible region of spectrum. The 35 ing 0.25 f. units, at that the lithium is placed in the interstitial Scintillation Substances having such emission spectrum sites of crystal lattice in the quantity of q formula units, more effectively work with the semiconductor detectors, another part of lithium ions are placed in the sites of the because the cheap silicon/germanium semiconductor detec lattice Substituting the lutetium ions in the quantity of p tors have the two-tree times less sensitive in a blue region of formula units. The positive effect of intercalation of the spectrum in comparison with green, and moreover red 40 lithium ions into the interstitial sites of structure is achieved region of spectrum. A substitution of Lu ions for the opti due to cally inactive Gd, Sc., Y, and La ions allows to control a (a) an intercalation is followed by the minimal change in lattice parameter and to grow the crystals free from a a crystal structure of Substance; mechanical stresses reducing a crystal cracking during an (b) an intercalation of the lithium ions gives rise to a after growth annealing and a cutting. Besides, a partial 45 formation of the reduced phases of Li Ce, i.e. a pres substitution of an expensive lutetium for the cheap La, Gd, ence of the lithium ions in the scintillation substances and Y reduces a cost of Scintillation Substance. of Ce, Li gally-p2-Si-Ost-p and Ce, Lig+p The ion radiuses of Y (1.016 A), La (1.190 A), Eu (1.073 Lu2-2-A-Si-Os, promotes to a stabilization A), Gd (1.061 A), Tb (1,044 A) are appreciably larger than of cerium ions in the Cevalence state, that apprecia the Lu (0.72 A) ion radius. At interaction of gamma 50 bly increases a light yield; quantum with a lattice a formation of the numerous quantity (c) an intercalation of the lithium ions gives rise to the of free electrons and the holes, wherefrom these electrons change of a conduction (A. A. Veshman, K. I. Petrov, were taken out by gamma-quantum, takes place. In conse “A functional inorganic lithium compounds' Moscow, quent recombination of electrons with holes an excitation of Energoizdat, (1996), 208 p.), that decreases an after lattice occurs, this energy transfers to the cerium ions which 55 glow time of substance, TABLE 1. emit in blue range of spectrum. Specially a recombination is For the #3 and #4 variants of substances, the lowerp and effective on the optical centers where the atoms having the q boundaries for a content of lithium are set to be equaled to very distinguishing radiuses are besides. For example, a 1x10' f. units, because this is the limit of lithium content substitution of part of lutetium ions for the lanthanum ions when the effect of a decreasing of afterglow and the effect of having significantly larger diameter results in a sharp light 60 increasing of light yield are possibly to observe. The upper yield increasing, that will be proved in the examples of limit of the content of lithium in scintillation substance is Substances confirmatory the given invention. In order to an determined by experimentally, at the total content of lithium electron-hole recombination has a maximal effect the use of ions exceeding 0.25 f. units a light yield intensity falls Small concentrations of the isomorphic Substituting dopants sharply due to a conduction of Substance excessively rises is required. At large concentrations a concentration quench 65 and Such scintillation Substance becomes inapplicable to the ing occurs and an efficiency is decreased, this lead to industrial applications for its direct purpose—for the regis reducing of light yield. On the basis of the above reasoning tration of X-ray, gamma and alpha radiation, TABLE 1. US 7,132,060 B2 21 22 All scintillation substances on the basis of silicate claimed Ceoloi2Lio. Lus.33La39ssDo.67Si6O26: in the #1 to #4 variants, inclusively, refer to a monoclinic Ceolois Lio.4sLu2.115Cd,Do 67SicO2ss: Syngony, a spatial group B2/b. The Scintillation Substances Ceolois Lio. Luz.3 Y2Oo. 67SigO25.9s; on the basis of silicate claimed in the fifth to tenth variants, Ceolois Lio.2sLu7ss EulisDog 7SiO26. All these composi inclusively, belong to another structural type, namely, apa tions were obtained in the forms of the single crystals, or the tite-brytolite with a spatial group P6/m, Z=1. The sub translucent, or the white nontransparent polycrystal ingots. stances claimed in the #6 and #7 variants have an important For example, the use of a melt of the common distinctive feature, namely, they contain the lithium Ceolois Lioso LuossLasDo.67SiO25.7s chemical composi ions of the total quantity (p+q) does not exceeding 0.55 f. tion and at the 2.5 mm/hour pulling rate of growing crystal units, where q denotes a quantity of lithium intercalated in 10 allows to grow from this melt the crystal of the the interstitial sites, p denotes a quantity of the lithium CeoloosLioss Luis, Laslo. 67SiO26 chemical composition. Substituting the rare-earth ions. The upper limit of q equaled The increasing of pulling rate and gradients on the melt up to 0.3 f. units is determined by experimentally. When the crystal interface allows to obtain the new crystalline scin quantity of lithium intercalated is above the indicated limit, tillation Substances over the range of compositions from the destruction of the structural type P6/m and the forma 15 CeoloosLiossLu1.077LasDo.67Si6O25.7s tO tion of inclusions of other phases takes place, which deter Ceolois LiossLuossLasDog/SigC2s 7s. In a generalized mine the scattering of light and the decrease of transparency form this new scintillation substance (the variants #6 and #7) ofascintillating crystal. The upper limit of p equaled to 0.25 has the following chemical formula: Ce, Li Luoss--- f. units is determined by the fact that an apatite-similar ADog/Si-O.g. where the variables q and p does not structure is retained at the substitution of the rare-earth exceed a value of 0.3 f. units and 0.25 f. units, respectively, atoms for lithium only for case, when a substitution of a variable Z is changed within the limits from 5x10"f units rare-earth atoms placed in the large nine-coordinated sites to 8.9 f. units. occurs, because only Such sites let a distortion and a devia To determine the boundaries of compositions of scintil tion from an ideal symmetry. With this the seven-coordi lation Substances which possibly to grow in the form of a nated sites, the second position for rare-earth ions in the 25 single crystal according to the #9 and #10 variants, the structure, are always occupied by the rare-earth elements. following Substances of an initial composition of melt were The lower boundaries for the contents of lithium ions p and tested: Ceolois LiLusoss SiO26: q are determined by the fact that at the quantity lower than Ceolois LissLus.73ssiaO25.7s: Ceolois Lillos Lusoss SiaC26: the 5x10"f units limit a technical result, lying in increasing Ceolois Lisu 1.7ss La7SiO2ss: of the light yield and decreasing of the afterglow of Scin 30 Ceolois Lila Lussss Y2SiO25.9 tillation, cannot be reached. Ceolois Li2Lu2.8ssGdaSiO2s 9. All these compositions For the variants #9 and #10 the upper limit of the content were obtained in the form of single crystals or the translu of lithium is determined to 1.55 f. units, because apatite cent, or the white nontransparent polycrystal ingots. For brytolite structure remains a stable over a wide substitution example, the use of a melt of the Ceolois LiLusoo,SiO2 range of elements of first position for the lithium ions. A 35 chemical composition and at the 0.5 mm/hour pulling rate of Substitution of large quantity of the basic-forming cerium growing crystal allows to grow from this melt the single ions for lutetium and cerium both in the mono-cation and crystal of the CeoloosLiLusoo, SiO2 chemical composition. double cerium silicates, being the analogues, lets to decrease The increasing of pulling rate and gradients on the melt the quenching effect of cerium luminescence and new Sub crystal interface allows to obtain the new crystalline scin stance obtains the Scintillation properties. 40 tillation Substances over the range of compositions from Our experimental researches showed that the crystals of CeoloosLiLus.997SiO26 to Ceolois Liss Lus735Si6O25.7s. In CeLiR-Si-O and Ross Dog, SiO2, where R-La, Gd, a generalized form this new Scintillation Substance (the grown by Czochralski method have a high optical quality, variants #9 and #10) has the following chemical formula: however they are behind the lutetium oxyorthosilicate crys Ce, Li Luo- A SiO2, where the variables q and p tals both in a density and in a light yield. To improve the 45 does not exceed a value of 0.3 f. units and 0.25 f. units, most important Scintillation parameters we have grew the respectively, a variable Z is changed within the limits from following crystals: Ceolois iGd29ss Luo SicO26: 5x10 f. units to 8.9 f. units. CeoloisiLa2.9ssueSi6O26: Ceolois LiGds.oss Lus SiO4O26: We executed a sciagram analysis of the powdered Ce, Ceolois LiLusoss SiO26. Ceolois Lio.4s Lus.93s SisC26. LiLuo-Si-O crystal samples using X-ray diffrac Ceoloisio.2Gd29ssLuo.33Do 67SigC26. 50 tometer. The analysis showed that the Ce, Li Luo Ceoloisio.33Eu 1.9ssLugaDo.67Si6O26. Si-O single crystals being crystallized in a hexagonal Ceoloisio 2.5Gd29ssLuo.2sDo.67SigC26. Syngony and may be classified to an apatite-brytolite struc Ceolo Lio.2s Yg.989Lu2.23–0.67Si6O25.9 tural type with a spatial group P63/m. Z=1. The indexing Ceool Lioss Y3.989Lao.9Lu3.33-0.67Si6O25.9 X-ray diffraction pattern of the Ceoloo LiLuso, SiOs crys Ceo.12 Liolos Las ossLus ssDo.67SiO26. The numerous 55 tal is presented on FIG. 4. Taking into account all 35 reflects experiments with different growth conditions let to obtain from the planes at the 20 angles of reflection over the range this Substances in the polycrystalline forms only. The testing from 15 degrees to 60 degrees, we calculated the lattice cell of polycrystal of the Ceolois LiLusoss SiO2 composition parameters which are equaled to a 11.66 A and c=21.58 A. shows that this new Scintillation Substance has near a The measurements of crystals density were carried out density, a light yield and a decay time, to the known Ce:LSO 60 according to a standard procedure of hydrostatic weighing, crystal this method is utilized in geology during ten-years. In these To determine the boundaries of composition of scintilla experiments we used the bulk polished samples weighing tion substances of the variants #6 and #7 which possibly to about 8-15 grams. The measurements were fulfilled in a grow in the form of single crystal we have tested the distilled water preliminary boiled during 20 minutes to Substances having an initial composition of melt: 65 remove an oxygen and cooled to the room temperature. A Ceoloi2Lio. Lus.33La3.9ssDo.67Si6O26: temperature of water was being measured with an accuracy Ceoloi2Lio.2Lu2.33LagossDo.67Si6O26: 0.1° C. To provide the minimal errors, each sample was US 7,132,060 B2 23 24 weighed five times, in this case an error of determination of lamp. The results of the afterglow effect measurements for crystal samples density did not exceed 0.001 gram/cm. The the different samples are presented in TABLE 1. results of the measurements are presented in TABLE 1. An experimental study of dependence of Scintillation BRIEF DESCRIPTION OF THE DRAWING decay time and a light yield in the 410–450 nm range of spectrum on chemical composition of crystals was carried out utilizing an emission of radionuclide 'Co as described The essence of proposed technical solutions is illustrated in the article (E. G. Devitsin, V. A. Kozlov, S.Yu. Potashov, by the following drawings: A. I. Zagumennyi, Yu. D. Zavartsev “Luminescent proper FIG. 1 depicts the fragment of phase diagram of Lu.O. ties of Lu.Also crystal doped with Ce” Proceeding of 10 SiO system. International Conferences “Inorganic Scintillators and their FIG. 2 shows the scheme of the optimal dimensions of a applications” (SCINT 95), Delft, the Netherlands, Aug. crystal and crucible for a case of crystal growth by Kyropou 20 Sep. 1, 1995). The results of the measurements are los method. presented in TABLE 1. FIG.3 depicts a flow chart of crystal growth by Kyropou The measurements of a luminescence intensity and a time 15 of an afterglow were fulfilled with the polished samples of los method for a case of partly crystallized melt. 8–15 grams weight. The intensity and afterglow of reference FIG. 4 shows the X-ray powder diffraction pattern of sample were the same after the gamma-radiation and ultra CeoloosLioslus.947Si6O25.9s crystal. violet (UV) radiation exposures, so for the systematic mea All crystals fabricated and examined during the fulfilment Surements the UV-excitation set was used. A luminescence of the given invention were grown from the iridium cru of the samples was excited by the standard 12 W UV-lamp cibles, the chemicals with the extra-purity of 99.99% and during the 60 minutes exposure, after the Switching-out of 99.999% were used as the source reagents. the lamp a fluorescence decreasing was recorded during 120 minutes with a photomultiplier FEU-100 or a photodetector DETAILED DESCRIPTION OF THE FD-24K connected with oscilloscope Tektronix TDS 3052 25 or multimeter Agilent 34401A lined with computer. A varia INVENTION tion of intensity of the samples having a strong afterglow effect are characterized by an exponential dependence hav TABLE 1 shows the results of testing of the synthesised ing a time constant about 25–35 minutes, these samples Scintilating Substances. The values of the light yields, the maintain a strong fluorescence during more than the 180 30 decay times of Scintillation, the afterglow times, the densi minutes. The samples having a low afterglow effect are ties, the atomic numbers (Z) are compared for different characterized by the dependence having a time constant compounds. The values of light yield are presented in units about several decades seconds. For some samples an after relative to a light yield of “the reference” Cecco Luoss glow effect was not observed after switching-out of the SiOs sample (the Ce:LSO prototype crystal).

TABLE 1. 'Comparison of Scintilating characteristics of the Scintilation Substances of different compositions. After Light glow Decay yield, presence Density Luminescence Atomic time (relative (relative (gram? range number Compositions of Substances (ns) units) units) cm) (nm) Zeir Ceoloo24Lu1.99s.SIOs 43.3 1.O 1.O 7.406 415-430 63.8 Ceo,00Lu2.075 Slo.962O5.038 445 1.OS 1.O 7.409 420-440 64.O Ceo,002Lu2.074Slo,962O5.038 43.4 1.O O.8 7.408 420-440 64.O Ceo,001sLu2.0445Tboo3Sio962O5.038 34.2 O.33 1.O 7.399 420-440 64.O 535. 550 Ceo,001sLu2.0645Tboooseulo,005Sio962O5.04 34.7 O.32 1.OS 7.406 420-440 64.O 535. 550 620-63S Ceo.0025Lu2.0685Yo,005Slo.962O5.038 42.7 1.09 O.9 7.403 425-445 64.O Ceo.0025Lu2.0685 Sco.005Slo.962O5.038 41 O.95 O.8 7.403 420-440 64.O Ceo.0025Lu2.0685 Lao.005Slo.962O5.038 43 1.12 O.8 7.404 430 450 64.O Ceo.0025Lu2.049Lao.02Slo,962O5.038 44.1 1.27 O.9 7.394 430 450 63.9 Ceo,003 Llo,005Lu2.049Lao.02Slo.962O5.038 41.3 1.38 O.9 7.393 430 450 63.9 Ceolo2LiLus.98Si6O26 36 O.8 0.7 7.314 415-430 62.6 Ceolois LiLugGd2.985Si6O26 35.2 0.4 No 7.012 420-440 60.6 Ceolois Lio.45 Lus 935Si6O25.65 36 O.9 O.2 7.331 415-430 62.6 Ceolois LiLugLa2.985Si6O26 38 1.4 O.3 6.701 420-440 59.1 Ceo,003LiLus.997Si6O26 39.7 1.2 O.3 7.318 415-430 62.6 Ceo,003 Lillos Llls 947Si6O25.97 39 1.2 O.3 7.310 415-430 62.6 Ceolois LissLus.735Si6O25.9 35 0.75 O.2 7.270 415-430 62.6 Ceolois LiLu3Gd5985Si6O26 31 O.3 No 6.691 430 440 58.3 Ceoloo Li2Lu3.698Gds. Si6O26. 34 O3S No 6.784 430 440 59.0 Ceolo-Li 1.2Llls.66Eulo.2Si6O25.95 33 O.25 O.2 7.285 420-440 62.3 620-63S 28 O3S O.2 7.095 420-440 61.3 535. 550 Ceoloo.2Li 1.45 Lus.29sy 2.5Si6O25.93 42 1.1 O.S 6.645 425-445 58.3 US 7,132,060 B2 25 26

TABLE 1-continued Qomparison of scintillating characteristics of the Scintilation substances of different compositions. After Light glow Decay yield, presence Density Luminescence Atomic time (relative (relative (gram range number Compositions of Substances (ns) units) units) cm) (nm) Zefir Ceo,001sLii.3Llls.3985LaossiéO26 42 1.2 O.S 7.198 430 450 62.O Ceolois Lio. Lus.33Gd2.985Do.67Si6O26.06 32 0.4 No 7.083 430 440 61.0 Ceolois Lio.33 Lu7.3Eu 1985Do.67Si6O26.1 34.5 O.09 No 7.019 420-440 61.4 620-63S Ceolois Lio.25Lus.28Gd2.985Do.67Si6O26.05 36 O.S No 7.073 430 440 60.9 Ceo,011 Lio.2Lu2.23Ys.989Do.67Si6O25.95 41 1.O 0.7 S.261 425-445 46.6 Ceoloi? Lio. Lu3.33Y5.989Do.67Si6O26 44 1.4 1.O 5.749 425-445 S1.O Ceo.o12 Lio.05Lus.33La3.98slo.67Si6O26 44 1.2 1.O 6.570 430 450 58.3 Ceo,003 Lio.55Lu.077 Laslo.67Si6O25.9 41 O.8 No S.S49 430 450 51.4

EXAMPLE 1. conical part of the boule was used. The parameters of “reference’ sample are presented in TABLE 1. Growth of known a “reference Ce:LuSiOs crystal hav Experiment #2. (The equilibrium conditions, charge com ing the Lu/Si 2 ratio, and also the growing of crystal having position of 50% (LuO +CeO)/50% SiO). A growing of a ratio of formula units of (Lu+Ce)/Si=2.061 (y=0.015), crystal was executed from an iridium crucible of the 40 mm which is out of compositions range of variant No.1 of given 25 in diameter under a good thermal insulation conditions in a invention. protective argon atmosphere (99.5% volume of argon and Due to a strong data spread about the crystal parameters 0.5% volume of oxygen), at pulling rate of 2 mm h", published in the different issues, the parameters of commer rotation rate of 15 rp.m. The initial charge of a melt had a cial Ce:LuSiOs crystals may be accepted as the most composition described by a chemical formula of reliable data. The higher light output is demonstrated by the 30 CeolouloossiOS. In these growth conditions the crystal LSO crystals, having a concentration of cerium ions equaled approximately 18 mm in diameter and 45 mm length was to 0.12 at. 96 (or about 0.002 f. units), the chemical formula grown, the crystal did not contain the fine scattering inclu of reference crystal is Ceoloo LuossiOS. Taking into sions and was a colourless. The content of cerium, lutetium account that the segregation coefficient of the cerium ions 35 and silicon ions was determined in crystal by electron between a melt and growing crystal is equaled about k=0.2, microprobe analysis using the commercial spectrometer. A it is needed to charge a crucible with the starting material composition oftop conical part of the crystal is characterised having a cerium concentration about 0.6 at. '% (or in the by the chemical formula of CeoloosLuo, SiolossOsos, hav formula units: 0.012 f. units). A ratio of the LuC), and SiO, ing ratio of (Lu--Ce)/Si=2.061. To the bottom of crystal the oxides should be calculated taking into account the pecu 40 concentration of cerium ions is being increased, and ratio of liarities of a directional crystallization method (Czochralski (Lu+Ce)/Si becomes a lower than 2.061. Obviously, that method, Stepanov's method, the Bridgman method or any Such crystal cannot be used as a “reference’ sample, because other method of a directional crystallization). We have grew its composition is differed from composition of know Lu the “reference” Ce:LuSiOs crystals by Czochralski method CeSiOs crystal. in the conditions of low temperature gradients (Experiment 45 Experiment #3. (Charge composition is 46% (LuC)+ #1) and in conditions of high temperature gradients (Experi CeO)/54% SiO). A growing of crystal was executed from ment #2 and #3). an iridium crucible of the 40 mm in diameter under a good Experiment #1. (The non-equilibrium conditions, charge thermal insulation in a protective atmosphere (99.5% vol composition of 50% (Lu C+CeO)/50% SiO). A growing ume of argon and 0.5% Volume of oxygen), at pulling rate of crystal was carried out from an iridium crucible of the 40 50 of 2 mm h", rotation rate of 15 round per minutes (r.p.m). mm in diameter under a weak thermal insulation in protec In accordance with a composition is denoted by an arrow 2 tive argon atmosphere (100% Volume of argon), at pulling of FIG. 1 it is needed to use the original charge composition rate of 3.5 mm h", rotation rate of 15 rp.m. The initial of 46%(LuO +CeO)/54%SiO, which corresponds to a charge of a melt had a composition described by a chemical melt having the Ceolo2LuissSilosoC4920 chemical com formula of Ceolo2LuloossiOS. In these conditions a crystal 55 position. In these conditions the crystal 52 mm in length and approximately 16 mm in diameter and 54 mm length was 16 mm diameter was grown. The crystal was colourless, but grown, a top of boule was colourless and did not have the it included the fine scattering inclusions, an amount of which fine scattering inclusions, but a bottom of boule had the was increased from a top to a bottom of a boule. The content cracks. The content of cerium, lutetium and silicon ions was of cerium, lutetium and silicon ions was determined in a top determined in crystal by electron microprobe analysis using 60 part of crystal by electron microprobe analysis using the the commercial Cameca Camebax SX-50 spectrometer. A commercial spectrometer. A composition of the crystal is composition of top conical part of the crystal is characterised within the compositions range between the by the chemical formula of Ceoloo.IluloossiOs having ratio Ceoloo.22Luoo, SioCs (a top part of a boule) and the of (Lu--Ce)/Si equaled exactly to 2, that is possible in the CeoloosLuoss SioloC49s (a bottom part of boule). conditions of crystallisation far from the equilibrium. How 65 A comparison of Scintillation parameters of couple of ever in the bottom of crystal the ratio of (Lu--Ce)/Sibecomes samples, fabricated in the experiments #1 and #3, had less than 2. For fabrication of “reference’ sample the top of shown, that they have approximately identical light output US 7,132,060 B2 27 28 under gamma excitation, and both samples demonstrated tion into the plats of 1 mm thickness, a diamond saw with approximately the same decay time T 43 ns. inner cutting edge of 0.2 mm thickness was used. In a result of cracks the losses were ~1%. In next stage the plats were EXAMPLE 2 glued together and cut into the rods with size of 1x1 x 11 mm. In result of cracks the losses achieved -3%. In the final A confirmation of the invention in the particular forms of stage the rods were glued into the blocks containing approxi implementation—the method of making of Scintillation Sub mately 30x30 rods in each, the blocks were mechanically stances. To grow a large single crystal by Kyropoulos polished from one or both faces of scintillating elements. method according with the variants #1, #2, #3, and #4, an During this processing the losses were no more than 0.1%. optimal Scintillation Substance having a composition of 10 Thus, in a result of cracks the total losses achieved about charge characterised by an oxides mole ratio of 51.9% 4%. (CeO+LuO +AO+LiO)/48.1% SiO, was chose. At For comparison the known Ce:LuSiOs crystal 50 mm in Such oxides ratio, the compositions of a melt and of a crystal diameter and 105 mm length was grown by Czochralski are characterised by a chemical formula of Ce, Li, method using a crucible 100 mm in diameter and 100 mm Lu2.076 --A Sio962Osloss, where A is at least one ele 15 height, the crystal was grown from a melt of initial compo ment selected from the group consisting of Gd. Sc, Y. La, Eu, sition characterised by chemical formula Tb, x is a value between 1x10' f. units and 0.02 f. units, Z CeoloLugossiOs. After the cutting of boule at the packs is a value not exceeding 0.05 f. units, q+p is a value not 50 mm in diameter and 11 mm length the cracks were exceeding 0.025 f. units. observed in volume of 3 slabs from total 8 slabs. During The growing of crystal 78 mm in diameter was executed fabrication of rods with size 1x1x11 mm having one from iridium crucible of 96 mm in inner diameter and about mechanically polished face the losses of crystalline material 112 mm height using the computer-controlled installation in a result of cracks and spalls achieved totally about 32%. equipped with a weighing system of growing crystal. Placed The same technological Scheme was used for a growing in an optimal thermal insulation crucible was filled with the and a cutting of the crystals having compositions: mixed chemical reagents, a crystal growing was carried out 25 CeLio.osLu2.026-Slo.962Os.oos-e- CeLio.02Lu2.072-y in a flowing protective nitrogen atmosphere (99.7% volume Sio.962Oso34. CeLu2.066---Laolo Sio.962O5.038, Ce, of nitrogen with 0.3% volume of oxygen). A weight of Lu2.036-Yo,04Sio.962Osloss. CeLio.2Lu2006 starting charge of crucible was 4400 grams. An initial charge Gdoo4Sio962Osos, Ce, LionsLu2.071---Tb-Sio962O4.9ss. had a chemical composition Ce, Lu2.076 Sio962O.soss, char with a different content of cerium, X is a value between acterised by the oxides mole ratio of 51.9% (LuO+CeO)/ 30 1x10" f. units and 0.02 f. units. 48.1% SiO. The single crystal rod of 12x12 mm section The chemical compositions of the melts offered in the was used as a seed crystal. The pulling rate of crystal boule given invention and a growing of crystals by Kyropoulas was being changed from 1 mm/hr to 8 mm/hr at the different method allow sharply to reduce the losses of crystalline stages of process. The shouldering of crystal from the seed Scintilation material in the stages of cutting of large boules. size until diameter size of approximately 75–78 mm was 35 accomplished along crystal length from 5 mm to 25 mm, EXAMPLE 3 after that the boule was grown at constant cylindrical diameter of 75–78 mm. The finishing of growth was carried Method of making of the scintillation substances in form out by means of increasing of pulling rate when the boule of Scintillating ceramics on the basis of lanthanum and weight achieved the desired value of about 90% of charge 40 lutetium oxyorthosilicate differed in that the mixture of (the crystallized melt fraction is 90%). The moment of chloride water solution of Lu, La, Ce and liquid of SiCl, are breaking off of a crystal from a melt was fixed by the used as a starting material for preparation of charge of weighing system. An annealing and a cooling of crystal to composition characterised by the oxides mole ratio of 51.9% room temperature was being carried out during 30 hours. (Lu O+LaO,+CeO)/48.1%SiO, An ammonium carbon Grown at these conditions crystal had 3910 grams in a 45 ate water solution was added to the said mixture. Then this weight of and 12.5 cm length. Due to Such technology, the mixture was filtering, drain and drying. After calcination at effect of crucible bloat is eliminated. The enlarge/distension 1400° C. the obtained oxides mixture stirred with addition of of iridium crucible during cooling of melt occurred if the Solvent and low-melting impurities, which promote an amount of residual melt is occupied more than 20% of atoms diffusion through boundary of grains during a final crucible volume. The enlarge and bloat of crucible sharply 50 high temperature annealing. The numerous compounds may decreases a life time of very expensive iridium crucible, and, be used as the low-melting impurities, which do not influ therefore, the production cost of a crystal boule is being ence on an emission of Ce" ions. Our investigations showed increased. that the small additives of Li, Na, K, Cs, Be, B. F. Al, S, Cl, An obtained crystal boule was used for measurement of Zn, Sc., Ga, Ge, Se, Br, I, Sn, and In ions do not lead to percentage loss of crystalline materials after a slicing, a 55 decrease of light output of Scintillating ceramics. A sintering sawing of boule into the thin elements, a screening and aid of Mg., P. Ca, Ti, V. Cr, Mn, Fe, Co, Ni, As, Sr, Zr, Nb, rejection of debris, the broken elements and elements having Mo, Cd, Sb, Ba, Hf, Ta, W, Pb, and Bi ions decreases or the Small cracks. The second kind of losses depend on a completely suppresses of Ce" ions emission. The sintering thickness of diamond saws, however these losses easy to aid of lithium compounds, for example, LiCl, Li2GeF6. calculate taking into account a thickness of a saw, so they do 60 LiFeO, LiBO promote for production of good optical not considering in given example. quality scintillation ceramics. After removal of the trace of The sawing of boule at the packs of 78 mm in diameter water and organic components, two ways of synthesis of and 11 mm length was fulfilled by the diamond saw with the ceramic are possible. inner cutting edge having the thickness of 0.6 mm. After this A first method. The oxide materials with the additives of stage was obtained the 9 slabs, which had not the cracks and 65 LiGeOs, LiBO was charged into a soft platinum capsule, spalls. At this stage of fabrication the losses was 0%. During then the capsule was pumped in a vacuum and the hole was the second stage the packs were cut in perpendicular direc solder using a gas-jet. After ceramic was being synthesising US 7,132,060 B2 29 30 in the capsule, which was placed under a massive press-form The growing by Czochralski technique of lutetium-yt at temperature 1300° C. under 1000 atm. pressure during 2 trium-lantanium-cerium orthosilicate of the chemical com hours. position of Ceoloo.2Lu 1.324Yo.7Laolos Sio962Ososs was A second method. The oxide materials with the additives executed from the iridium crucible of the 38 mm in diameter of Li-GeO, LiBO, was pressed under 2000 atm pressure. 5 and 38 mm height, the pulling rate was 3 mm/hour and After that during the few hours the pressed pellets (of square rotation rate of 15 rp.m. Crystallization executed from the or other shape) were annealed in a vacuum at temperature melt characterised by the mole ratio of oxides 51.9% about 1700–1840° C. To eliminate the violet colour centers (Lu 20+YO+Ce2O+LaO)/48.1%SiO in protective and to improve an optical quality, the pellets were annealed argon atmosphere (99.5% volume of argon with 0.5% vol during 24 hours on air at temperature about 1300° C. at the 10 ume of oxygen). The crystal 16 mm in diameter and 60 mm final stage. In a result of these actions the Scintillation length was colourless and did not have the cracks during ceramic products covered by thin white coat at all sides were growth process, however the cracks appeared in the middle obtained. Produced by this technique elements may be used part of crystal boule during 24 hours cooling stage. The top for the X-ray computer tomography systems. of crystal did not contain the fine scattering inclusions, but 15 the numerous scattering inclusions were in the bottom of EXAMPLE 4 boule. Under gamma excitation the sample from the top of crystal have demonstrated the light output about 1.3 times A Scintillation Substance based on a silicate comprising a higher than light output of a “reference” Ce:LuSiOs crystal lutetium (Lu) and cerium (Ce) characterised in that the described in EXAMPLE 1. composition of the Substance in the form of a single crystal is represented by the chemical formula Ce, Lu. A EXAMPLE 6 Si-Os, where A is at least one element selected from the group consisting of Gd. Sc, Y. La, Eu, Tb, and Ca, X is a A Scintillation Substance containing a lithium (Li) ions, value between 1x10' fu. and 0.02 fu. y is a value between according to variants #3 and #4 of given invention, having 25 the composition represented by the chemical formula of 0.24 fu. and 0.09 fu. Z is a value between 1x10" fu. and Ce, Li Lu 2-2-A-Si-Os, where A is at least one 0.05 flu. element selected from the group consisting of Gd. Sc, Y. La, The oxide chemicals (LuC), TbO, CeO, SiO) with purity of 99.995% were used for the growing by Czochralski Eu, and Tb, x is a value between 1x10" f. units and 0.02 f. method of lutetium-terbium-cerium orthosilicate of the com units, y is a value between 0.024 f. units and 0.09 f. units, 30 q is q is a value between 1x10" f. units and 0.2 f. units, p position of Ceoloo Luo Tboossio962Osloss. The crystal is a value between 1x10' f. units and 0.05 f. units, Z is a growth was executed from an iridium crucible of the 54 mm value does not exceeding 0.05 f. units. in diameter and 54 mm height containing the melt charac To obtain the CeoloosLioloosLu2.049Laoloo2Sio962Osoas terised by a mole ratio of oxides 51.9%(CeO+LuO + crystal, the following method of making of the samples was TbO)/48.1%SiO. The pulling rate was 2 mm/hour, rota tion rate of 15 rp.m. Crystallization was executed in a 35 used: the initial chemicals of lutetium oxide, silicon oxide protective argon atmosphere (99.5% volume of argon with and lithium carbonate in the quantities determined by mole 0.5% volume of oxygen). The crystal of 55 mm length and relationship of oxides 51.9% (Lu C+LiO+CeO+AO)/ 26 mm in diameter had a high optical quality and did not 48.1% SiO, were thoroughly mixed, pressed in pellets and comprise the fine scattering inclusions. The polished syhthesised in a platinum crucible during 10 hours at 1250° 40 C. Then by means of induction heating the pellets were samples from this crystal were used for the measurement of melted in an iridium crucible in a hermetically sealed parameters are presented in TABLE 1. chamber in protective nitrogen atmosphere (99.7% volume The growing by Czochralski technique of lutetium-lan of nitrogen with 0.3% volume of oxygen). A cerium oxide thanum-cerium orthosilicate of the composition of was added into the melt before a crystal growth. The crystal Lu, Laoo-CeoloolsSio94Osog was executed from the iridium as 60 mm in diameter and cylindrical part of 45 mm length was crucible of the 38 mm in diameter and 38 mm height grown by Kyropoulas method from the iridium crucible of containing the melt characterised by the oxides mole ratio of the 76 mm in diameter and 78 mm height. The volume of the 51.9%(CeO+LuO +LaO)/48.1%SiO. The pulling rate initial melt was equaled to 290 cm. The pull rate of crystal was 3 mm/hour, rotation rate of 10 rp.m. Crystallization was boule was varied from 1 mm/hr to 8 mm/hr at the different executed in protective argon atmosphere (99.5% volume of so stages of growth, the rotation rate was 10 rp.m. When the argon with 0.5% volume of oxygen). The crystal 17 mm in boule has grown, it was breaking off from the melt and diameter and 20 mm length had the high optical quality and cooled during 30 hours till room temperature. The polished did not comprise the fine scattering inclusions. The polished samples from this boule were used for the measurements of samples from this crystal were used for measurement of parameters presented in TABLE 1. parameters presented in TABLE 1. The analogous growth ss The growing by Czochralski technique of the Scintillation conditions were used for production of many samples, Substance on the basis a lutetium-cerium orthosilicate, con which parameters are presented in TABLE 1. taining a lithium, having the chemical composition of Ce, Liolos Lu 2026. Sio962Osloos was executed from iridium EXAMPLE 5 crucible of the 36 mm in diameter and 38 mm height with 60 the pulling rate 2.7 mm/hour and rotation rate of 14 r.p.m. A confirmation of the invention in the particular forms of Crystallization was executed from the melt of composition implementation for variants #2 of given invention is the determined by the mole ratio of oxides 51.9% (LuC+ Scintillation Substances in the form of a single crystal having CeO+LiO)/48.1% SiO in a protective argon atmosphere the chemical formula of CeLuz.076---, (99.7% volume of argon with 0.3% volume of oxygen). The LaYSiolog2O.soss, where X is a value between 1x10' fu. 65 crystal 19 mm in diameter and 60 mm length was colourless and 0.02 ful., m is a value does not exceeding 0.05 ful.., n is and did not have a cracking during growth process and in a a value between 1x10' fu. and 2.0 fu. stage of 22 hours cooling. As the top so the bottom of crystal US 7,132,060 B2 31 32 did not contain the fine Scattering inclusions except of the The same technological Scheme was used for a growing peripheral part of volume of the thickness about 0.5–0.7 and a cutting of the crystals having the compositions: mm. Under gamma excitation the sample from the top part of crystal demonstrated about the same value of light output CeolosLio.4LugosCeoloo Lio.2Luo.279 as light output of a “reference” Ce:LuSiOs crystal described in EXAMPLE 1. The same technological scheme was used EXAMPLE 9 for a growing and a cutting of the crystals having compo sitions: Ce, Liolo2Lu2.072-Sio962Oso34. Ce, Lu2.036 A Scintilation Substance according to variants #7 on the Yoo-Sio962Os.oss: Ce, Lio.2Lu2006- Gdoo Sio.962Osos, basis of a lutetium-cerium silicate containing lithium and Ce, Lios Luozi--Tb-Sio962O49ss, with a different con 10 cation vacancies and having the composition represented by tent of cerium, x is a value between 1x10"f units and 0.02 the chemical formula Ce, Li Luoss----Do.67A. SiO26. f. units. where A is at least one element selected from the group consisting of Gd, Sc. Y. La, Eu, and Tb, x is a value between EXAMPLE 7 1x10"f units and 0.1 f. units, q is a value between 1x10' 15 f units and 0.3 f units, p is a value between 1x10' f. units A Scintillation Substance according to variants #5 on the and 0.25 f. units, Z is a value between 5x10"f units and 8.9 basis of a lutetium-cerium silicate containing the cation f. units. vacancies and having the composition represented by the A growing by Czochralski technique of the Scintillation chemical formula CeLuoss Dog, Sid O2, where X is a Substance on the basis of a mono-cation lutetium-cerium value between 1x10' f. units and 0.1 f. units. silicate containing lithium and cation vacancies and having The growing by Czochralski technique of the Scintillation the composition represented by the chemical formula Substance on the basis of a mono-cation lutetium-cerium Ceoloo.2Lio.2Lu722s, o.o.7La2SiO25.9 was executed from silicate having the chemical composition of iridium crucible of the 37 mm in diameter and 40 mm height Ceoloo.2Luo.32s log2SiO26, executed from an iridium cru with the pulling rate of 2.7 mm/hour and rotation rate of 12 cible of the inner diameter of 37 mm and 40 mm in height 25 r.p.m. Crystallization was executed from the melt of sto with the pulling rate of 2.7 mm/hour and rotation rate of 14 ichiometric composition in protective nitrogen atmosphere r.p.m. Crystallization was executed from the melt of sto (99.8% volume of nitrogen with 0.2% volume of oxygen). ichiometric composition in protective argon atmosphere The crystal 22 mm in diameter and 52 mm length diameter (99.7% volume of argon with 0.3% volume of oxygen). The and 58 mm length was colourless and did not have a crystal 22 mm in diameter and 58 mm length was colourless 30 cracking during growth and in stage of 12 hours cooling. The and did not had a cracking during growth process and in a bulk volume of crystal contained some fine scattering inclu stage of 12 hours cooling. The bulk volume of crystal sions. The scintillation samples were made in according with contained some fine Scattering inclusions, the density of technology described in EXAMPLE 1. inclusions was increased to the bottom part of boule. The The same technology scheme was used for a growing and Scintillation samples were made in according with technol 35 a cutting of the crystals having compositions: ogy described in EXAMPLE 1. Ceoloo24Lio.2Lu 1.22s-Do.67YsSi6O25.9 The same technology scheme was used for a growing and Ceoloo Lio. Lus.324Do. 67YSiaC2s.99s. a cutting of the crystals having compositions: Ceoloo LionsLu4279Do.67GdsSigO25.9s. Ceolo4Luo.29Do.67SiO26. Ceol Luo.2s Do. 67Si6O26. It is nec Ceoloo LiossLug. 109Do.67Tbo2SiO2s. 8. essary to note that the increasing of cerium ions concen 40 Ceoloo2Lio. Luo.423Do 67Las.gSiO25.9s. trated reduced a quantity of scattering inclusions. EXAMPLE 10 EXAMPLE 8 A Scintillation Substance according to the variants #8 and A Scintillation Substance according to variants #5 on the 45 #9 on the basis of lutetium-cerium silicate containing a basis of a lutetium-cerium silicate containing lithium and the lithium (Li) in the quantity not a less than 1.0 f. units and cation vacancies and having the composition represented by having the composition represented by the chemical formula the chemical formula Ce, Li Luoss--Do.67Si6O26. Ce, Li Luo SigO26, where X is a value between where x is a value between 1x10" f. units and 0.1 f. units, 1x10' funits and 0.1 f. units, q is a value in the quantity q is a value between 1x10" f. units and 0.3 f. units, p is a 50 does not exceeding 0.3 f. units, p is a value in the quantity value between 1x10" f. units and 0.25 f units. does not exceeding 0.25 f. units. The growth by Czochralski technique of the scintillation An important distinguishing technical indication of given Substance on the basis of a mono-cation lutetium-cerium Scintilation Substances is their melting point, which is a silicate containing lithium and cation vacancies and having little higher than 1700° C., that is more than 300° lower than the composition represented by the chemical formula of 55 for crystals crystallised in a structural type of lutetium Ce, Li Luoss Dog, Si-O.g. was executed from the iri oxyorthosilicate. The low temperature of melting is the dium crucible of the 37 mm in diameter and 40 mm height essential advantage for a crystal growth by Czochralski with the pulling rate 2.7 mm/hour and rotation rate of 12 technique, because in this case the time of iridium crucibles r.p.m. Crystallization was executed from the melt of sto operation is increased in tens time. There is more important ichiometric composition in protective nitrogen atmosphere 60 a long time of usage, if the crystals growth is being carried (99.7% volume of nitrogen with 0.3% volume of oxygen). out by Stepanov's method. An utilization of Stepanov's The crystal 22 mm in diameter and 52 mm length was method opens a possibility to grow the several Scintillating colourless and did not have a cracking during a growing and crystals simultaneously, for example, with size 2x2x100 in a stage of 12 hours cooling. The bulk volume of crystal mm or the size 1x1x50 mm. It allows to eliminated the contained some amount of fine Scattering inclusions. The 65 expensive stage of a cutting of a large boule into thin rods. Scintillation samples were made in according with technol During a cutting possibly to lost of 20%–50% of single ogy described in EXAMPLE 1. crystal material, that considerably increases the manufac US 7,132,060 B2 33 34 turing cost of Scintillating elements for medical Micro 0.5% volume of oxygen), the pulling rates were 5 mm/hour Positron-Emission computer Tomography (MicroPET). and 10 mm/hour and rotation rate was 11 rp.m. in these In the process of growth of a profiled crystal from a melt, growth conditions the crystal approximately 35 mm length the crystal cross-section is determined by the form of melt and 18 mm in diameter was grown, the boule had a white column. Different physical effects are used for the shaping of 5 yellow colour and did not have the fine Scattering inclusions a melt. A formation of a square cross-section melt column is even at the 10 mm/hour pulling rate. The polished sample of carried out by means of an iridium former. A design of the this crystal under gamma excitation demonstrated the light formers and methodology of calculation of the optimal output about 10 time lower than a light output of a “refer growth conditions are described in the book (P. I. Antonov, ence” Ce:LuSiOs crystal, a technology of fabrication of L. M. Zatulovski, A. S. Kostygov and others “An obtaining 10 which is described in EXAMPLE 1. On the basis of this an of profiled single crystals and products by Stepanov's upper limit of substitution of lutetium ions by other elements method’, L., “Nauka', 1981, page 280.). in the substances of variant #10 having the chemical formula A growing of a profiled crystal by Stepanov's method was of Ce, Li Luo-A-Si-O26, was set at the value of executed from an iridium crucible equipped with the iridium Z=8.9 f. units. In this case the crystals have a significantly former, having an outer edge cross-section of 2x2 mm. 15 lower density and light output, however the cost of charged which determined the cross-section of a pulling crystal. To reagents, and, therefore, a manufacturing cost of Scintillation obtain the Ceolois Lisool us oossigO2soos crystal crystallis crystals are being decreased appreciably. Such crystals are ing in a hexagonal structural type, the charge of Stoichio being interested for utilization in the sensors, for which the metric composition having the chemical formula more important parameter is a low price and a high resis CeoloasLisoo Lusoos SiO2soos was used. The following tance of Scintillator to the outside exposure. Such as a high method was used for the burden preparation. The source temperature, a big humidity, a very high level of radiation, reagents of a lithium carbonate, lutetium oxide and silicon which may destroy, for example, a gamma dosimeter. oxide were thoroughly mixed and partially synthesised in a The same technological scheme was used for a growing of platinum crucible during 10 hours at 1300° C. Then, by crystals having the compositions: means of induction heating the powder was melted in an 25 Ceoloo Lii.2Lu3.89sGds. SigO26. iridium crucible in flow protective nitrogen atmosphere Ceoloa Li2Lusso Eulo.2SiO25.9 (99.7% volume of nitrogen with 0.3% volume of oxygen). A Ceol Li2Lu79ScossiO2ss. cerium oxide was added into the melt before a crystal Ceoloo2Lil 4slug.29sy 2.5Si6O2ss. growth. The former allowed to grow from one to nine Ceolools Lii.3Lus.39ss Laos SigO25.9. profiled crystals simultaneously. Seeding was fulfilled onto 30 While the foregoing description represent the preferred the crystal obtained by Czochralski technique. A seed crystal embodiments of the present invention, it will be understood was cut along a crystallographic direction of the axis of six that various additions and/or substitutions may be made order. The profiled crystals were pulled out of melt at a speed therein without departing from the spirit and scope of the of 3–20 mm/hour without rotation. Upon the crystal reach present invention. One skilled in the art will appreciate that ing the length of 50 mm they were broken away from the 35 the invention may be used with many modifications of former by a sharp increasing of the pulling speed and 30 structure, forms, arrangement, proportions, materials, and minutes later they were being extracted from installation. components and otherwise, used in the practice of the The profiled crystal rods were cut into the few scintillat invention and which are particularly adapted to specific ing elements with sizes 2x2x10 mm. The polished samples environments and operative requirements, without departing of Ceolois Lisool us gossicOsloos Crystal were used for 40 from the principles of the present invention. The presently measurements of parameters presented in TABLE 1. disclosed embodiments are therefore to be considered in all The same technological Scheme was used for a growing respects as illustrative and not restrictive. and a cutting of the crystals having the compositions: Ceoloo LiLus.99s SiO26. Ceolo-LiLusogSiO26. We claim: Ceol LiLuso Sig O26. Ceoloo2Lii.4sLus.79s-Si6O25.8 45 1. A Scintillation Substance based on a silicate comprising Ceolools Lisus.89ss-Si6O25.9. a lutetium (Lu) and cerium (Ce) characterized in that the EXAMPLE 11 composition of the Substance is represented by the chemical formula A Scintillation Substance according to variant #10 on the 50 Ce, Lu2+2-Si-Osly basis of silicate containing a lutetium (Lu) and cerium (Ce) and characterised in that it contains a lithium Li in the X is a value between 1x10 fu. and 0.02 flu. quantity exceeding 1.0 fu. and its composition is repre y is a value between 0.024 fu. and 0.09 fu. sented by the chemical formula Ce, Li Luo 2. A Scintillation Substance according to claim 1, charac A Si-O, where A is at least one element selected from 55 terised in that the composition of the substance in the form the group consisting of Gd. Sc, Y. La, Eu, and Tb, X is a value of a single crystal is represented by the chemical formula between 1x10"f units and 0.1 f. units, q is a value between 1x10" f. units and 0.3 f. units, p is a value between 1x10 Ce, Lu2.076 Slo.962O5.038, f. units and 0.25 funits, Z is a value between 5x10' fu. and X is a value between 1x10' fu. and 0.02 fu. 8.9 f. units. 60 3. A method of making the Scintillating Substance accord To obtain a Scintillation Substance of composition of ing to claim 1, characterised in that a single crystal is being CeoloasLi. LuloosLaoo-Ys 7ss SiO26 crystallising in a hex grown by a directional crystallization method from a melt agonal Syngony, the charge of Stoichiometric composition made from the charge of the composition defined by mole having the chemical formula of Ceolois Li Luoos ratio of oxides 51.9% (LuO +CeO)/48.1% SiO. Laolo2Gds 7ss SiO2 was used. A growing of crystal was 65 4. A method of making the Scintillating Substance accord executed from an iridium crucible of the 40 mm in diameter ing to claim 1, characterised in that a single crystal is being in a protective atmosphere (99.5% volume of nitrogen with grown by Czochralski method from a melt made from the US 7,132,060 B2 35 36 charge of the composition defined by mole ratio of oxides a melt made from the charge of the composition defined by 51.9% (Lu,0+CeO)/48.1% SiO, mole ratio of oxides 51.9% (LuC+LiO+CeO)/48.1% 5. A Scintillation Substance based on a silicate comprising SiO. a lutetium (Lu) and cerium (Ce) characterised in that the 13. A Scintillation Substance based on a silicate compris composition of the Substance in the form of a single crystal ing lutetium (Lu) and cerium (Ce) characterised in that it is represented by the chemical formula contains a lithium Li in a quantity that does not exceed 0.25 Ce, Lu2+2--A-Si-Osly fu. and its composition is represented by the chemical formula where A is at least one element selected from the group consisting of Gd. Sc. Y. La, Eu, Tb, and Ca, 10 CeLateLu2-p2---A-Si-Os: p. X is a value between 1x10' fu. and 0.02 flu. where A is at least one element selected from the group y is a value between 0.024 fu. and 0.09 fu. consisting of Gd. Sc, Y. La, Eu, and Tb, Z is a value between 1x10 fu. and 0.05 fu. X is a value between 1x10' fu. and 0.02 fu. 6. The Scintillation Substance according to claim 5, char y is a value between 0.024 fu. and 0.09 fu. acterised in that the composition of the substance in the form 15 of a single crystal is represented by the chemical formula Z is a value between 1x10 fu. and 0.05 fu. q is a value between 1x10' fu. and 0.2 fu. Ce, Lu2.076 --A-Slo.962O5.038, p is a value between 1x10 fu. and 0.05 fu. where A is at least one element selected from the group 14. The Scintillation Substance according to claim 13, consisting of Gd. Sc. Y. La, Eu, Tb, and Ca, characterised in that the composition of the Substance in the X is a value between 1x10' fu. and 0.02 fu. form of a single crystal containing lithium Li in a quantity Z is a value between 1x10 fu. and 0.05 fu. that does not exceed 0.25 flu. and is represented by the 7. The scintillation substance according to claim 5, char chemical formula acterised in that the composition of the substance in the form CeLateLu2.076 ex-A-So.962O5.038 p. of a single crystal is represented by the chemical formula 25 where A is at least one element selected from the group CeLuz.076---La, Y,Slo.962O5.038: consisting of Gd. Sc, Y. La, Eu, and Tb, X is a value between 1x10' fu. and 0.02 flu. m is a value does not exceeding 0.05 flu. X is a value between 1x10' fu. and 0.02 fu. n is a value between 1x10' fu. and 2.0 fu. Z is a value between 1x10' fu. and 0.05 fu. 8. A method of making the Scintillating Substance accord 30 q is a value between 1x10' fu. and 0.2 fu. ing to claim 5, characterised in that a single crystal is being p is a value between 1x10 fu. and 0.05 fu. grown by a directional crystallization method from a melt 15. A method of making the Scintillating Substance made from the charge of the composition defined by mole according to claim 13, characterised in that a single crystal ratio of oxides 51.9% (Lu.O+AO+CeO)/48.1% SiO, is being grown by a directional crystallization method from where A is at least one element selected from the group 35 a melt made from the charge of the composition defined by consisting of Gd. Sc, Y. La, Eu, Tb, and Ca. mole ratio of oxides 51.9% (Lu C+LiO+AO+CeO)/ 9. A method of making the Scintillating Substance accord 48.1% SiO. ing to claim 5, characterised in that an oversized crystal is 16. A Scintillation Substance based on a silicate compris being grown by Kyropoulos method from a melt made from ing lutetium (Lu) and cerium (Ce) characterised in that it the charge of the composition defined by mole ration of 40 contains lithium Li and its composition is represented by the oxides 51.9% (Lu,0+A.O.--CeO)/48.1% SiO, where A chemical formula is at least one element selected from the group consisting of Gd, Sc., Y, La, Eu, Tb, and Ca. CeLateLllo.33--Do.67Si6O26 p. 10. A Scintillation Substance based on a silicate compris X is a value between 1x10 fu. and 0.1 fu. ing lutetium (Lu) and cerium (Ce) characterised in that it 45 contains a lithium Li in a quantity that does not exceed 0.25 q is a value between 1x10' fu. and 0.3 flu. fu. and its composition is represented by the chemical p is a value between 1x10 fu. and 0.25 flu. formula 17. A Scintillation Substance based on a silicate compris ing lutetium (Lu) and cerium (Ce) characterised in that it CeLateLu2-p2-Si-Osky-p 50 contains lithium Li and its composition is represented by the X is a value between 1x10' fu. and 0.02 fu. chemical formula y is a value between 0.024 fu. and 0.09 fu. q is a value between 1x10' fu. and 0.02 fu. CeLateLllo.33-x-p-z 0.67A-Sisozge p is a value between 1x10' fu. and 0.05 fu. where A is at least one element selected from the group 11. A Scintillation Substance according to claim 10, char 55 consisting of Gd. Sc, Y. La, Eu, and Tb, acterised in that the composition of the substance in the form X is a value between 1x10' fu. and 0.1 fu. of a single crystal containing lithium Li in a quantity that q is a value between 1x10' fu. and 0.3 fu. does not exceed 0.25 flu. and is represented by the chemical formula p is a value between 1x10' fu. and 0.25 fu. 60 Z is a value between 5x10 fu. and 8.9 fu. CeLateLu2.076 p-Slo.962O5.038 p. 18. A Scintillation Substance based on a silicate compris X is a value between 1x10' fu. and 0.02 fu. ing lutetium (Lu) and cerium (Ce) characterised in that it q is a value between 1x10" fu. and 0.2 fu. contains lithium Li and its composition is represented by the p is a value between 1x10' fu. and 0.05 fu. chemical formula 12. A method of making the Scintillating Substance 65 according to claim 10, characterised in that a single crystal Ce, LiLug Si6O26, is being grown by a directional crystallization method from X is a value between 1x10' fu. and 0.1 fu. US 7,132,060 B2 37 38 19. A scintillation substance based on a silicate compris- contains lithium Li in a quantity exceeding 1.0 ful. and its ing lutetium (Lu) and cerium (Ce) characterised in that it composition is represented by the chemical formula contains lithium Li in a quantity exceeding 1.0 fu. and its CeLila Lug--e-A-Si6O26 p. composition is represented by the chemical formula where A is at least one element selected from the group CeLiliate Lug-x-Sigo26 p. consisting of Gd. Sc, Y. La, Eu, and Tb, X is a value between 1x10' fu. and 0.1 flu. X is a value between 1x10' fu. and 0.1 fu. s q is a value between 1x10' fu. and 0.3 flu. q is a value between 1x10' fu. and 0.3 fu. p is a value between 1x10' fu. and 0.25 fu. p is a value between 1x10' fu. and 0.25 flu. Z is a value between 5x10 fu. and 8.9 fu. 20. A scintillation substance based on a silicate compris- 10 ing lutetium (Lu) and cerium (Ce) characterised in that it k . . . . UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT NO. : 7,132,060 B2 Page 1 of 1 APPLICATIONNO. : 10/502960 DATED : November 7, 2006 INVENTOR(S) : Alexander Zagumennyi et al. It is certified that error appears in the above-identified patent and that said Letters Patent is hereby corrected as shown below:

Title page, item 62 insert --Related U.S. Application Data This application claims priority to PCT Application No. PCT/RU2004/000094 filed on March 12, 2004, which application claims the benefit of Russian Patent Application No. 2003132127 filed on November 4, 2003, both of which are incorporated herein by reference in their entireties for all purpose.--

Signed and Sealed this Twenty-first Day of February, 2012

David J. Kappos Director of the United States Patent and Trademark Office UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT NO. : 7,132,060 B2 Page 1 of 1 APPLICATIONNO. : 10/502960 DATED : November 7, 2006 INVENTOR(S) : Alexander Zagumennyi et al. It is certified that error appears in the above-identified patent and that said Letters Patent is hereby corrected as shown below:

In the Claims

Column 34, line 45, Claim 1 should read as follows: -1. A scintillation substance based on a silicate comprising lutetium (Lu) and cerium (Ce) characterized in that the composition of the substance is represented by the chemical formula CexLu2+2y-XSi1-yO5+y, X is a value between I X 10-4 fu. and 0.02 fu. y is a value between 0.024 fu. and 0.09 fu.--

Column 35, lines 2-12, Claim 5 should read as follows: --5. A scintillation substance based on a silicate comprising lutetium (Lu) and cerium (Ce) characterized in that the composition of the substance in the form of a single crystal is represented by the chemical formula CexLu2+2y-X-ZAZSi1-yO5+y, where A is at least one element selected from the group consisting of Gd. Sc, Y, La, Eu, Tb, Ca, X is a value between 1 x 10-4 flu. and 0.02 flu. y is a value between 0.024 fu. and 0.09 fu. Z is a value between 1 x 10-4 flu. and 0.05 fu.--

Signed and Sealed this Second Day of September, 2014 74-4-04- 2% 4 Michelle K. Lee Deputy Director of the United States Patent and Trademark Office