THE INFLUENCE of LIGHT ANION IMPURITIES UPON Sri2(EU) SCINTILLATOR CRYSTALS 2831

Total Page:16

File Type:pdf, Size:1020Kb

THE INFLUENCE of LIGHT ANION IMPURITIES UPON Sri2(EU) SCINTILLATOR CRYSTALS 2831 2830 IEEE TRANSACTIONS ON NUCLEAR SCIENCE, VOL. 63, NO. 6, DECEMBER 2016 The Influence of Light Anion Impurities Upon SrI2(Eu) Scintillator Crystals S. E. Swider, S. Lam, and A. Datta, Member, IEEE Abstract— To better identify the influence of light anion impu- as metallic strontium is known to react aggressively with rities on the scintillation performance, small boules of SrI2(Eu) nitrogen Halide impurities such as chlorine and bromine may were grown by the vertical Bridgman-Stockbarger method, each 0 2− 3− be introduced via impurities in the hydrogen-iodide acid used co-doped with 0.2% of one of the following: C ,CO3 ,N , 2− − 3− 2− 2− − − to convert strontium carbonate into strontium iodide. Likewise, O ,OH ,PO4 ,S ,SO4 ,Cl and Br . Residual impurity concentrations were measured, and the scintillation performance residual phosphorous may be present in the hydrogen-iodide of resulting detectors was characterized. Oxygen was tolerated acid, or in the minerals from which strontium is mined. up to 0.2% on a molar basis. Sulfur proved to be highly To maintain and improve purity, crystal growers handle SrI2 detrimental to both crystallinity and scintillation performance. and similar salts in low-moisture, argon-filled glove boxes. Nitrogen produced additional emission near 480 nm. This study They also employ melt-filtration [5] and reactive gasses such suggests that SrI2(Eu) readily incorporates anion impurities, which may substitute for iodine, but these may also be removed as HI(g) [10]–[11]. However, since it is not clear which light before and during growth by volatilization. Purity metrics for impurities are most detrimental to single-crystal growth and starting materials should include sulfur and carbon, as well as scintillation performance, current purification efforts are not oxygen and H2O. thoroughly guided. Some may be unnecessary. Index Terms— Anions, co-doping, crystal growth, impurities, In this study, we examined the impact of light scintillators, strontium iodide. impurities upon crystallinity and scintillation performance of SrI2(4%Eu). Individual crystals of were grown with I. INTRODUCTION 0.2 mol% of the light-impurity containing co-dopant. HE SrI2(Eu) scintillator, first discovered by R. Hofstadter Although co-doping has been previously used to improve the Tin 1968 and rediscovered five decades later [1]–[3], has performance of various scintillators, such as LaBr3 [12] and shown great promise in radiation detection community due CeBr3 [13], this study was concerned with identifying unfa- to its excellent performance. Reported properties include a vorable co-dopants. Resulting data provide improved guidance high light yield ranging from 80,000 to 120,000 ph/MeV at for precursor purification. Previously, we studied the impact 662 keV, resolution as low as 2.6%, and a proportional light of cation co-doping and found many metallic impurities segre- yield response [3]–[6]. Its limitations include hygroscopicity, gated according to the Hume-Rothery rules of solid solubility, a slightly long decay time, and self-absorption [7], [8]. and were rendered benign. Cations with similar ionic radii and Advances in precursor production have led to the availability valences to strontium (e.g. Ca, Ba, Na) became incorporated of high quality, beaded SrI2 starting material. Nevertheless its into the lattice, and degraded scintillation performance [14]. deliquescence makes the material susceptible to inadvertent introduction of light impurities present in air. The 5N classi- II. EXPERIMENTAL METHODS fication of the starting material addresses metallic impurities only– oxygen and moisture are accounted separately. Well- A. Crystal Growth dehydrated strontium iodide typically has oxygen levels of Single crystals of SrI2(4%Eu) were grown from stoichio- 30-50 ppm by weight, which is about 650-1050 ppm on a metric mixtures of anhydrous 99.99% SrI2, and 99.99% molar basis. Residual carbon, sulfur, nitrogen, chlorine, and EuI2, (Sigma Aldrich). During initial compounding, each was 0 2− bromine are not typically measured. Carbon and sulfur impu- co-doped with of one each of the following anions: C ,CO3 , rities may be introduced stochastically from starting materials, −3 2− − −3 2− 2− − − N ,O ,OH ,PO4 ,S ,SO4 ,Cl and Br . In cases which are often mined as sulfides and converted into carbon- where the dopant compound was not listed as anhydrous from ates before synthesis into halide salts [9]. Nitrogen also has the the vendor, it was dehydrated at 175◦Cand8× 10−6 torr potential to be introduced stochastically during salt synthesis, for 2 hours. The specific dopants are listed in Table I. With the exception of SrCl2 and SrBr2, 2000 mol ppm of each Manuscript received March 14, 2016; revised July 20, 2016; accepted October 17, 2016. Date of publication October 26, 2016; date of current anion was added with respect to the SrI2(Eu) matrix. The version December 14, 2016. This work was supported by the U.S. Depart- target value of 2000 mol ppm (0.2 mol%) was chosen because ment of Homeland Security, Defense Nuclear Detection Office, under the it represents the high end of impurity content that might be competitively awarded contract HSHQDC-13-C-00080. This support does not constitute an express or implied endorsement on the part of the Government. present in purchased SrI2. The chlorine, and bromine anions The authors are with CapeSym Inc., Natick, MA 01760 USA (e-mail: were added as 2000 mol ppm with respect to the strontium [email protected]; [email protected]; [email protected]). cation, and therefore those preliminary anion concentrations Color versions of one or more of the figures in this paper are available online at http://ieeexplore.ieee.org. were 4000 ppm. Note that the certain anion molecules contain Digital Object Identifier 10.1109/TNS.2016.2622059 multiple oxygen atoms, e.g. 2000 mol ppm SO4 contains 0018-9499 © 2016 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission. See http://www.ieee.org/publications_standards/publications/rights/index.html for more information. SWIDER et al.: THE INFLUENCE OF LIGHT ANION IMPURITIES UPON SrI2(EU) SCINTILLATOR CRYSTALS 2831 TABLE I is located within a dedicated argon-filled glove box maintained ANION DOPANTS ADDED IN THIS STUDY at less than 3 ppm moisture. During oxygen analysis, small assays (< 0.5g) are heated to approximately 3000◦Cinthe presence of graphite. As the assay is volatilized, oxygen is released and reacts with the graphite to form carbon dioxide. A high purity helium gas stream sweeps the CO2 to an IR cell. The calibrated CO2 absorption curve is integrated and compared to the original sample weight, for a parts-per-million by weight oxygen reading. After growth, the SrI2(Eu) boules were opened inside the ELTRAglovebox, in order to minimize air exposure before testing. Sectioning was performed in the same glovebox. Small detectors (φ 10 mm ×6 mm height) were made from the midpoint of each boule, and tested for scintil- lation response to 662 keV radiation. Pulse-height spectra were measured using a Hamamatsu R6231-100 photomulti- plier tube (PMT) located in a glovebox at less than 3 ppm 8000 mol ppm oxygen. Finally, we note that the least moisture. PMT output signals were processed by a Canberra pure co-dopant, strontium hydroxide (94% purity), introduces 2005 pre-amplifier, an Ortec 672 amplifier set at 10 μ s 120 mol ppm metallic impurities (6% x 2000 ppm), which shaping time, and an Ortec Easy-MCA-2k multichannel ana- should be within the tolerance of the strontium iodide matrix. lyzer. Photopeak centroids and energy resolutions were deter- We have reported previously that the strontium iodide matrix mined using Ortec Maestro peak-fitting software. Samples rejects most cations during crystallization, according to Hume- were cupped within a specular reflector (Vikuiti ESR, 3M) to Rothery rules for forming a solid solution [14]. improve light collection. Resulting light yield was estimated Starting concentrations of metallic impurities in the SrI2 by comparing the gamma response of the SrI2(Eu) detector to and EuI2 beads were approximately 90 and 60 ppm by mol NaI(Tl) and LYSO(Ce) scintillators made by Hilger Crystals, 3 (30 and 15 ppm by wt), respectively, as determined by each sized 5×5×5mm, with corrections made for the PMT 66-element inductively-coupled plasma mass spectroscopy quantum efficiency. (ICP-MS). The same lot of SrI2 and EuI2 beads was used Decay traces were collected using a Tektronix TDS throughout this study. 784C oscilloscope with a 50 terminator to match the Prior to loading, each ampoule was cleaned with aqua cable impedance. Each recorded trace was an average of regia and acetone, and baked for over 1 hour at 850◦Cat 10,000 decay pulses. Decay times were determined by fitting 2 × 10−5 torr. After vacuum baking, the ampoules were a single exponential decay function from the maximum pulse isolated with a valve, and transferred to the glove box without intensity, I0,to0.1I0. introduction of air. Assays were loaded in an argon-filled Emission wavelength spectra were obtained by exciting the glove box at <2 ppm moisture. After loading, the vacuum- samples at 365 nm with an Hg lamp and collecting the emis- compatible valve was reattached and the loaded ampoules were sion with a Horiba MicroHR spectrometer. The spectroscopy heated to 150◦Cat2×10−5 torr for at least 1 hour, to remove system is described in more detail in Lam et. al. [15]. All residual moisture, before being sealed with a torch. detectors were enclosed in an air-tight optical jig for the For increased throughput, a φ45mm, stainless steel, measurement. multiple-ampoule holder was used to grow four 10-millimeter EDS measurements were made on a JEOL JSM-6300 SEM diameter crystals simultaneously in quartz ampoules, by the system at Geller MicroAnalytical of Topsfield, MA; using vertical Bridgman-Stockbarger method, in a 2-zone furnace carbon tape, KI, SrF2, and CsI references.
Recommended publications
  • Strontium Iodide Radiation Instrument (SIRI) – Early On-Orbit Results Lee J
    Strontium Iodide Radiation Instrument (SIRI) – Early On-Orbit Results Lee J. Mitchella, Bernard F. Phlipsa, J. Eric Grovea, Theodore Finnea, Mary Johnson-Ramberta, b W. Neil, Johnson a United States Naval Research Laboratory, 4555 Overlook Ave. S.W., Washington, DC 20375 b Praxis Inc., 251 18th Street South, Suite 610, Arlington, VA 22202 Abstract— The Strontium Iodide Radiation Instrument (SIRI) or proven components to reduce costs associated with drawing is a single detector, gamma-ray spectrometer designed to down that risk. space-qualify the new scintillation detector material europium- A number of new gamma-ray scintillation materials look doped strontium iodide (SrI2:Eu) and new silicon promising and have been proposed for space missions [1] [2] photomultiplier (SiPM) technology. SIRI covers the energy [3] [4], while silicon photomultiplier (SiPM) readout range from .04 - 8 MeV and was launched into 600 km sun- technologies are also quickly replacing traditional synchronous orbit on Dec 3, 2018 onboard STPSat-5 with a photomultiplier tubes (PMTs) in instrument concepts [5] [6] one-year mission to investigate the detector’s response to on- [7]. The goal of the Strontium Iodide Radiation Instrument orbit background radiation. The detector has an active volume (SIRI) mission is to study the performance of new SiPM of 11.6 cm3 and a photo fraction efficiency of 50% at 662 keV technology and a new scintillation material, europium-doped for gamma-rays parallel to the long axis of the crystal. Its strontium iodide (SrI2:Eu), for space-based gamma-ray spectroscopic resolution of 4.3% was measured by the full- spectrometry.
    [Show full text]
  • Manipulating Nonproportionality of Strontium Iodide Crystals with High-Flux Irradiation by 137Cs Gamma Rays
    Manipulating Nonproportionality of Strontium Iodide Crystals with High-Flux Irradiation by 137Cs Gamma Rays By David D. Caudel Dissertation Submitted to the Faculty of the Graduate School of Vanderbilt University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY in Physics May 2017 Nashville, Tennessee Approved: Keivan Stassun, Ph.D. Arnold Burger, Ph.D. Richard Haglund, Ph.D. Ashley Stowe, Ph.D. In dedication to my children and in loving memory of my father. Also, to the Fisk-to-Vanderbilt Bridge Program, for giving me the chance to fulfill my dream of becoming a physicist. ii ACKNOWLEDGMENTS The work in this dissertation has been supported by the following entities and funding sources: the Fisk-to-Vanderbilt Bridge Program, the BOLD fellowship, the GAANN fellowship CFDA 84.200, the NSF Grant HRD 1547757 (CREST-BioSS Center), the Vanderbilt Discovery Grant, and Fisk University’s subaward with ORNL GO under prime contract DE-AC52-07NA27344 from the United States Department of Energy. iii TABLE OF CONTENTS Page DEDICATION .......................................................................................................................... ii ACKNOWLEDGEMENTS ............................................................................................... iii LIST OF TABLES ....................................................................................................................... vi LIST OF FIGURES .........................................................................................................
    [Show full text]
  • United States Patent 0 "3 Cc Patented Apr
    2,882,298 _, United States Patent 0 "3 cc Patented Apr. 14, 1959 1 2 a mixture of equimolar quantities of nickel iodide (Nilz) and either sodium iodide (NaI) or zinc iodide (Znlz) 2,882,298 will provide the required increased ratio of iodide ion to nickel ion concentration. Alternatively, a catalyst PREPARATION OF ACRYLIC ACID ESTERS mixture of one mol of nickel chloride and three mols of Benjamin J. Luberolf, Stamford, Conn., assignor to sodium iodide may be used. American 'Cyanamid Company, New York, N.Y., Although the reason for the synergistic e?ect is not a corporation of Maine entirely understood, the activity of such a catalyst mix No Drawing. Application March 26, 1956 ture in the aforedescribed process is materially increased Serial No. 573,658 ‘over that of either nickel iodide as catalyst or the relative 1y inert supplemental iodide alone. In general, how 2 Claims. (Cl. 260-486) ever, the ratio of iodide 'ion to nickel ion is greater than two but less than about ?ve. It is therefore a good practice to use about equal amounts of nickel iodide This invention relates to a novel and improved method 15 and the supplemental iodide. for‘. preparing acrylic acid and esters thereof. More par Typically illustrative soluble metal iodide compounds ticnlarly, it relates 'to a liquid phase reaction whereby other than nickel iodide will include a variety of broad acetylene, carbon monoxide and .either ‘water or an alco classes. However, the prime requirement is that the hol all being present in equivalent amounts are reacted alkali metal be soluble in the reaction medium.
    [Show full text]
  • Tuesday, June 3 Plan of the Day
    Tuesday, June 3 Tuesday, June 3 Plan of the Day SORMA West 2008 moves from International House to an adjacent part of the campus: Stanley Hall and Bechtel Engineering Center, Sibley Auditorium. Contributed orals in parallel sessions will be given in the morning. Early in the noon hour, after a brief break (not long enough to return to the Doubletree or explore the campus), buses will load for the San Francisco and Muir Woods tours. Box lunches will be provided. The buses will return to the Doubletree. Those who did not sign up for a tour are free for the afternoon and may wish to stop by the information desk for maps, restaurant guides, etc. 8:00am-12:00pm Information Desk Sibley Auditorium Foyer 9:00am-10:15am Parallel Sessions Stanley Hall and Bechtel/Sibley Aud. 10:15am-10:45am Break 10:45am-12:00 Parallel Sessions Stanley Hall and Bechtel/Sibley Aud. Noon- Lunch (Boxed) Afternoon SF Tour/ Muir Woods Tour Plan of the Day Page Tuesday-1 Tuesday, June 3 New Scintillators Tuesday AM I: Stanley 105 Chair: Chuck Melcher, Univ. of Tennessee Tuesday AM I: Stanley 105-1 Crystal Growth and Scintillation Properties of Strontium Iodide Scintillators Edgar Van Loef, Radiation Monitoring Devices, Inc. (RMD) Cody M. Wilson; Nerine J. Cherepy, Giulia Hull, Stephen A. Payne (LLNL); Woon-Seng Choong, William W. Moses (LBNL); Kanai S. Shah (RMD) Security applications and nuclear non-proliferation depend on the rapid identification of highly enriched uranium, weapons grade plutonium, radioactive sources and other special nuclear materials. Efficient detection of their gamma-ray signature is the most common method for identification and requires a scintillator that has a high light yield, good energy resolution, fast scintillation decay and high effective atomic number.
    [Show full text]
  • Maine Remedial Action Guidelines (Rags) for Contaminated Sites
    Maine Department of Environmental Protection Remedial Action Guidelines for Contaminated Sites (RAGs) Effective Date: May 1, 2021 Approved by: ___________________________ Date: April 27, 2021 David Burns, Director Bureau of Remediation & Waste Management Executive Summary MAINE DEPARTMENT OF ENVIRONMENTAL PROTECTION 17 State House Station | Augusta, Maine 04333-0017 www.maine.gov/dep Maine Department of Environmental Protection Remedial Action Guidelines for Contaminated Sites Contents 1 Disclaimer ...................................................................................................................... 1 2 Introduction and Purpose ............................................................................................... 1 2.1 Purpose ......................................................................................................................................... 1 2.2 Consistency with Superfund Risk Assessment .............................................................................. 1 2.3 When to Use RAGs and When to Develop a Site-Specific Risk Assessment ................................. 1 3 Applicability ................................................................................................................... 2 3.1 Applicable Programs & DEP Approval Process ............................................................................. 2 3.1.1 Uncontrolled Hazardous Substance Sites ............................................................................. 2 3.1.2 Voluntary Response Action Program
    [Show full text]
  • Chemical Names and CAS Numbers Final
    Chemical Abstract Chemical Formula Chemical Name Service (CAS) Number C3H8O 1‐propanol C4H7BrO2 2‐bromobutyric acid 80‐58‐0 GeH3COOH 2‐germaacetic acid C4H10 2‐methylpropane 75‐28‐5 C3H8O 2‐propanol 67‐63‐0 C6H10O3 4‐acetylbutyric acid 448671 C4H7BrO2 4‐bromobutyric acid 2623‐87‐2 CH3CHO acetaldehyde CH3CONH2 acetamide C8H9NO2 acetaminophen 103‐90‐2 − C2H3O2 acetate ion − CH3COO acetate ion C2H4O2 acetic acid 64‐19‐7 CH3COOH acetic acid (CH3)2CO acetone CH3COCl acetyl chloride C2H2 acetylene 74‐86‐2 HCCH acetylene C9H8O4 acetylsalicylic acid 50‐78‐2 H2C(CH)CN acrylonitrile C3H7NO2 Ala C3H7NO2 alanine 56‐41‐7 NaAlSi3O3 albite AlSb aluminium antimonide 25152‐52‐7 AlAs aluminium arsenide 22831‐42‐1 AlBO2 aluminium borate 61279‐70‐7 AlBO aluminium boron oxide 12041‐48‐4 AlBr3 aluminium bromide 7727‐15‐3 AlBr3•6H2O aluminium bromide hexahydrate 2149397 AlCl4Cs aluminium caesium tetrachloride 17992‐03‐9 AlCl3 aluminium chloride (anhydrous) 7446‐70‐0 AlCl3•6H2O aluminium chloride hexahydrate 7784‐13‐6 AlClO aluminium chloride oxide 13596‐11‐7 AlB2 aluminium diboride 12041‐50‐8 AlF2 aluminium difluoride 13569‐23‐8 AlF2O aluminium difluoride oxide 38344‐66‐0 AlB12 aluminium dodecaboride 12041‐54‐2 Al2F6 aluminium fluoride 17949‐86‐9 AlF3 aluminium fluoride 7784‐18‐1 Al(CHO2)3 aluminium formate 7360‐53‐4 1 of 75 Chemical Abstract Chemical Formula Chemical Name Service (CAS) Number Al(OH)3 aluminium hydroxide 21645‐51‐2 Al2I6 aluminium iodide 18898‐35‐6 AlI3 aluminium iodide 7784‐23‐8 AlBr aluminium monobromide 22359‐97‐3 AlCl aluminium monochloride
    [Show full text]
  • Quasi-Particle Spectra, Absorption Spectra, and Excitonic Properties Of
    Quasi-particle spectra, absorption spectra, and excitonic properties of sodium iodide and strontium iodide from many-body perturbation theory Paul Erhart,1, 2 Andr´eSchleife,2 Babak Sadigh,2 and Daniel Aberg˚ 2 1Chalmers University of Technology, Department of Applied Physics, Gothenburg, Sweden 2Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California 94550, USA We investigate the basic quantum mechanical processes behind non-proportional response of scin- tillators to incident radiation responsible for reduced resolution. For this purpose, we conduct a comparative first principles study of quasiparticle spectra on the basis of the G0W0 approxima- tion as well as absorption spectra and excitonic properties by solving the Bethe-Salpeter equation for two important systems, NaI and SrI2. The former is a standard scintillator material with well-documented non-proportionality while the latter has recently been found to exhibit a very pro- portional response. We predict band gaps for NaI and SrI2 of 5.5 and 5.2 eV, respectively, in good agreement with experiment. Furthermore, we obtain binding energies for the groundstate excitons of 216 meV for NaI and 195 ± 25 meV for SrI2. We analyze the degree of exciton anisotropy and spatial extent by means of a coarse-grained electron-hole pair-correlation function. Thereby, it is shown that the excitons in NaI differ strongly from those in SrI2 in terms of structure and symmetry, even if their binding energies are similar. Furthermore, we show that quite unexpectedly the spatial extents of the highly anisotropic low-energy excitons in SrI2 in fact exceed those in NaI by a factor of two to three in terms of the full width at half maxima of the electron-hole pair-correlation function.
    [Show full text]
  • Binary Ionic Nomenclature
    Nomenclature A systematic method of writing chemical formulas and naming compounds Chemical symbols Symbols are used to represent elements Either one capital letter, or a capital letter with a lower case letter Chemical formulas Formulas are used to represent compounds All formulas have more than one symbol Two or more capital letters All chemical names have two words No need to capitalize words in name I. Binary Ionic compounds Binary = two elements Ionic means cation and anion Cations (+ ions) are usually metals Anions (- ions) are usually nonmetals Therefore: Two elements, one metal and one nonmetal a) naming them Name the metal Name the nonmetal, changing the ending to “ide” Example: name MgCl2 Mg = magnesium Cl = chlorine, so write “chloride” Name is magnesium chloride Name these… NaF sodium fluoride Al2O3 aluminum oxide Ca3P2 calcium phosphide K3N potassium nitride BaS barium sulfide SrI2 strontium iodide Mg3N2 magnesium nitride BeI2 beryllium iodide b) Writing formulas Notice: subscripts in the name did not effect the naming of these compounds • The subscripts tell us how many of each element are present in the finished formula • SMALLEST POSSIBLE WHOLE NUMBERS Example: Al2S3 means 2 aluminum ions and three sulfurions in one “formula unit” • The subscripts are there to balance charges **ALL IONIC COMPOUNDS ARE NEUTRAL** b) Writing formulas - steps 1) Write the symbol for each ion • the element and its charge 2) Balance the charges • The total (+) charge must equal the total (-) charge • criss
    [Show full text]
  • Wo 2010/117346 A2
    (12) INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT) (19) World Intellectual Property Organization International Bureau (10) International Publication Number (43) International Publication Date 14 October 2010 (14.10.2010) WO 2010/117346 A2 (51) International Patent Classification: AO, AT, AU, AZ, BA, BB, BG, BH, BR, BW, BY, BZ, A61K 31/593 (2006.01) CA, CH, CL, CN, CO, CR, CU, CZ, DE, DK, DM, DO, DZ, EC, EE, EG, ES, FI, GB, GD, GE, GH, GM, GT, (21) International Application Number: HN, HR, HU, ID, IL, IN, IS, JP, KE, KG, KM, KN, KP, PCT/TR20 10/000081 KR, KZ, LA, LC, LK, LR, LS, LT, LU, LY, MA, MD, (22) International Filing Date: ME, MG, MK, MN, MW, MX, MY, MZ, NA, NG, NI, 9 April 2010 (09.04.2010) NO, NZ, OM, PE, PG, PH, PL, PT, RO, RS, RU, SC, SD, SE, SG, SK, SL, SM, ST, SV, SY, TH, TJ, TM, TN, TR, (25) Filing Language: English TT, TZ, UA, UG, US, UZ, VC, VN, ZA, ZM, ZW. (26) Publication Language: English (84) Designated States (unless otherwise indicated, for every (30) Priority Data: kind of regional protection available): ARIPO (BW, GH, 2009/02817 10 April 2009 (10.04.2009) TR GM, KE, LR, LS, MW, MZ, NA, SD, SL, SZ, TZ, UG, ZM, ZW), Eurasian (AM, AZ, BY, KG, KZ, MD, RU, TJ, (72) Inventor; and TM), European (AT, BE, BG, CH, CY, CZ, DE, DK, EE, (71) Applicant : BILGIC, Mahmut [TR/TR]; Tozkoparan ES, FI, FR, GB, GR, HR, HU, IE, IS, IT, LT, LU, LV, Mah.
    [Show full text]
  • THE PHYSICAL CHEMISTRY of METALS in THEIR MOLTEN HALIDES THESIS Presented for the Degree of DOCTOR of PHILOSOPHY in the UNIVERSI
    THE PHYSICAL CHEMISTRY OF METALS IN THEIR MOLTEN HALIDES THESIS presented for the degree of DOCTOR OF PHILOSOPHY in the UNIVERSITY OF LONDON By Lars-Ingvar Staffansson, Bergsingenjor, (Stockholm). London, December 1959, ABSTRACT The phase diagrams of the systems calcium- calcium chloride, calcium-calcium bromide and calcium- calcium iodide have been established by solubility measurements and differential thermal analysis. Each of the systems was found to have a eutectic a mono- tectic and a large miscibility gap. The eutectics are 3.3, 3.2 and 6.8 mole % calcium respectively, and the corresponding temperatures are 763, 728 and 760°C. The monotectics are at 99.5, 99.6 and 99.7 mole % calcium respectively and the corresponding temperatures are 826, 828 and 831°C. The consolute points are at 1338, 1335 and 1380°C and the corresponding compositions are 62, 64 and 74 mole % calcium. Discrepancies between this and previous work are mainly attributed to composition changes of the phases during quenching. A method has been developed that overcomes this difficulty. The depression of the freezing point of strontium by strontium chloride has also been determined. From the results of this work a model for the mutal solubility of metalS and their molten halides has been suggested. CONTENTS Page CHAPTER 1: INTRODUCTION 1 1.1 General Introduction 1 1.2 Relevant previous work on metal-molten salts. 4 1.2.1 General 4 1.2.2 Alkaline earth metal-metal halide systems. 12 CHAPTER 2: EXPERIMENTAL 24 2.1 Programme 24 2.2 Preparation and purity of materials 25 2.2.1 Calcium 25 2.2.2 Strontium 26 2.2.3 Calcium Chloride 26 2.2.4 Calcium Bromide 28 2.2.5 Calcium Iodide 28 2.2.6 Strontium Chloride 29 2.2.7 Pure Iron 30 2.2.8 Gases 31 2.3 Dry-box.
    [Show full text]
  • Standard X-Ray Diffraction Powder Patterns NATIONAL BUREAU of STANDARDS
    NBS MONOGRAPH 25—SECTION 1 9 CO Q U.S. DEPARTMENT OF COMMERCE/National Bureau of Standards Standard X-ray Diffraction Powder Patterns NATIONAL BUREAU OF STANDARDS The National Bureau of Standards' was established by an act of Congress on March 3, 1901. The Bureau's overall goal is to strengthen and advance the Nation's science and technology and facilitate their effective application for public benefit. To this end, the Bureau conducts research and provides: (1) a basis for the Nation's physical measurement system, (2) scientific and technological services for industry and government, (3) a technical basis for equity in trade, and (4) technical services to promote public safety. The Bureau's technical work is per- formed by the National Measurement Laboratory, the National Engineering Laboratory, and the Institute for Computer Sciences and Technology. THE NATIONAL MEASUREMENT LABORATORY provides the national system of physical and chemical and materials measurement; coordinates the system with measurement systems of other nations and furnishes essentia! services leading to accurate and uniform physical and chemical measurement throughout the Nation's scientific community, industry, and commerce; conducts materials research leading to improved methods of measurement, standards, and data on the properties of materials needed by industry, commerce, educational institutions, and Government; provides advisory and research services to other Government agencies; develops, produces, and distributes Standard Reference Materials; and provides calibration
    [Show full text]
  • United States Patent Office Patented Mar
    3,373,279 United States Patent Office Patented Mar. 2, 1968 1. 2 3,373,279 are as follows: the body should be optically integral, EUROPUM ACTIVATED STRONTIUM have good efficiency of energy conversion, have the ODOE SCNTLLATORS desirable geometry of the mass for energy absorption, Robert Hofstadter, Stanford, Calif., assignor, by mesne and have favorable geometry of the mass for light assignments, to Kewanee Oil Company, Bryn Mawr, Pa., emission reflector surface quality, and Window surface a corporation of Delaware quality. There usually should be a reflector surrounding No Drawing. Filed Jan. 29, 1965, Ser. No. 429,141 the crystal and it should have a high efficiency of reflec 5 Claims. (C. 250-71.5) tion and be uniformly and intimately fitted against the surface of the crystal. The window or light-pipe, which 0 may be nothing more than a portion of the crystal surface ABSTRACT OF THE DISCLOSURE not covered by the reflector, should have a good uniform This invention comprises a scintilation crystal com optical coupling with the mass of the crystal and have a posed of strontium iodide activated by europium. The good light transmitting efficiency from the crystal to the invention also comprises a radiation detector having a light detector. detecting element and a chamber optically coupled to Europium when used in amounts as low as about 10 this detecting element, having within the chamber a parts per million causes an emission peak at about scintillator consisting of strontium iodide activated with 4300-50 angstroms. about 10-16,000 parts per million of europium.
    [Show full text]