DOCSLIB.ORG

United States Patent (19) 11 Patent Number: 4,601,755 Mélard Et Al

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
United States Patent (19) 11 Patent Number: 4,601,755 Mélard Et Al United States Patent (19) 11 Patent Number: 4,601,755 Mélard et al. 45 Date of Patent: Jul. 22, 1986 (54) CERIUM BASED GLASSPOLISHING (56) References Cited COMPOSITIONS U.S. PATENT DOCUMENTS 75 Inventors: Pierre Mélard, Lagord; Marcel 3,262,766 7/1966 Nonamaker ........... ... 51/309 Peltier, La Rochelle; Francis Tastu, 3,768,989 10/1973 Goetzinger et 51/309 Nieul/sur/Mer, all of France 4,161,463 7/1979 Myers et al... ... SO2/263 73 Assignee: Rhone-Poulene Specialites 4,62,921 7/1979 Litvinov et al. P ... O - 0 - - - - - - - - - - - A as - - 50/9 Chimiques, Courbevoie, France Primary Examiner-Amelia B. Yarbrough Attorney, Agent, or Firm-Burns, Doane, Swecker & 21 Appl. No.: 635,828 Mathis 22 Filed: Jul, 30, 1984 57 ABSTRACT (30) Foreign Application Priority Data Cerium based glass polishing compositions, well adapted for the polishing, e.g., of optical glass, are com Jul. 29, 1983 FR France ................................ 83 2519 prised of (i) at least one crystalline phase of CeO2 type, 51) Int. Cl'................................................ C09G 1/02 and (ii) a crystalline phase which comprises a rare earth 52 U.S. C. ........................................ 106/3; 51/308; pyrosilicate having the formula Ln2-CeSi2O7, 51/309; 156/DIG. 63; 423/263 wherein Ln is at least one lanthanide or yttrium and x is 58 Field of Search ................... 106/3, 288 B, 287.34; a number ranging from zero to less than 2. 51/309, 308; 423/263; 156/DIG. 63; 502/263, 302, 304,303 59 Claims, No Drawings 4,601,755 1. 2 forming insoluble rare earth compounds, with the num CERIUM BASED GLASS POLISHING ber of equivalents of base being greater than or equal to COMPOSITIONS the number of equivalents of cerium and the pH of the reaction medium being higher than 6; BACKGROUND OF THE INVENTION 5 (b) the resultant precipitate is filtered; 1. Field of the Invention: (c) dried; and The present invention relates to novel cerium based (d) thence calcined. polishing compositions, a process for the preparation This process provides polishing compositions having thereof, and to the use of same in the polishing of glass, good homogeneity and reproducibility, good stability ceramics and other vitreous type materials. 10 upon suspension in water and good polishing efficacy. 2. Description of the Prior Art: However, the immediately aforedescribed process is Among the polishing compositions currently in use in not entirely satisfactory, since the anion typically em the glass industry, those based on the rare earths, and in ployed is fluoride which gives rise to those problems particular cerium, are generally the most effective and necessarily associated with the use of fluorides, in par efficient. Different processes too are known for the 15 production of such compositions. Thus, it has been ticular pollution which may be caused by the effluent proposed, in German Pat. No. 2,426,110, to precipitate therefrom, whether in liquid or gaseous state. an aqueous solution of a rare earth sulfate with sodium SUMMARY OF THE INVENTION hydroxide in the presence of molochite, and to then filter, wash, dry and calcine the precipitate to obtain the 20 Accordingly, a major object of the present invention desired polishing composition. Such a process does not is the provision of improved cerium based polishing permit the obtainment of polishing compositions having compositions which exhibit the following desirable completely satisfactory efficacy, particularly in view of characteristics: their heterogeneity, undefined structure and lack of (i) effectiveness, i.e., they enable the polishing of a reproducibility of the final products. These disadvan 25 generally ground glass surface as rapidly as possible; tages originate specifically from the operating condi (ii) acceptability, i.e., they will not scratch the glass tions of the process, wherein the concentration of the during the polishing operation; reagents changes over the course of the reaction and it (iii) inertness, i.e., they will not cause a detrimental is thus impossible to obtain defined products in a repro reaction on the surfare of the glass, e.g., they do not ducible fashion; they are also occasioned by the exis 30 display excessive chemical activity with respect to the tence of foreign compounds (molochite) and the pres glass, thereby avoiding the problems of burning, orange ence of sulfates, the precipitation of which by sodium peel, blisters, and the like; hydroxide yields mixtures of complex molecules, such (iv) a very long useful life or longevity, i.e., they are as double sulfates, hydroxysulfates and hydroxides, the suitable for use for the longest possible period of time amount and nature of which may vary-over the course 35 without deterioration or difficulties; of the reaction. (v) good stability in suspension, i.e., permitting a It has also been proposed, Chemical Abstracts, 80, homogeneous distribution of particulates or powder 51688 (1974), to produce cerium based polishing com thereof in appropriate bath and avoiding any deposits positions by precipitating ceric hydroxide with ammo thereof. nia from a solution of a rare earth nitrate, wherein the The dispersion, as aforesaid, is effective as soon as the cerium has been previously oxidized. Such a process composition is placed in suspension and remains so mandates a supplementary purification step by recrys during the entire operation. tallization with the ceri-ammoniacal nitrate and taking Such dispersions, moreover, do not foam; foaming up the calcined oxide in a dilute acid. The final prod causes overflowing, clogs the lines, reduces yields and ucts, moreover, do not have a satisfactory polishing 45 inconveniences the operating personnel. Furthermore, efficacy. Furthermore, such final compositions also do the subject compositions are readily re-suspended after not have satisfactory homogeneity or structural charac an extended stoppage and settling period, even if the teristics, and they are not reproducible. bath is charged with particles of polished glass (the In U.S. Pat. No. 3,768,989 a process is described for phenomenon of "caking'). the preparation of polishing compositions by the forma 50 tion of a precipitate of a rare earth carbonate-wollasto Also, the compositions of the invention are not toxic, nite, separation of the precipitate and the calcination thus preventing any problems of skin disorders or other thereof. And in U.S. Pat. No. 3,262,766 a process is diseases. They are, moreover, uniform, possess a pleas described for preparing polishing compositions by treat ing color and are easy to work with. They do not ad ing solutions of commercially available rare earth car 55 here to the glass after polishing, thereby permitting bonates with either fluosilicic or hydrofluosilicic acid. rapid cleaning, and are easy to flocculate, to eliminate Polishing compositions prepared by the processes de manufacturing rejects. scribed in either of these two U.S. patents, however, Briefly, the novel cerium based glass polishing com have disadvantages akin to those described above for positions of the present invention comprise at least one the compositions prepared according to the teachings of 60 crystallographic phase of the CeO2 type and a crystallo the 110 German patent. graphic phase comprising a rare earth pyrosilicate hav To eliminate the disadvantages of the aforementioned ing the formula Ln2-xCex.Si2O7, wherein Ln represents processes, a novel process has been proposed in French at least one element selected from among the lantha Pat. No. 2,472,601, assigned to the assignee hereof, in nides and yttrium and whereinx is greater than or equal accordance with which: 65 to 0 and less than 2. (a) a solution of a cerium salt is continuously mixed In addition to the aforesaid two essential crystallo with a basic solution and a solution of at least one acid graphic phases, the compositions of the invention may and/or salt, the anion or anions of which are capable of optionally comprise in certain cases other crystallized 4,601,755 3 4. phases of rare earth oxides or phases of silicon oxide, The normality of the basic solution used too is not a more or less crystallized. critical factor according to the invention; it also may vary over wide limits, but advantageously it ranges DETAILED DESCRIPTION OF THE from to 5N. INVENTION The proportion of the basic solution and the cerium More particularly according to the present invention, salt solution should be such that the number of equiva it has now surprisingly been found that unexpectedly lents of the basic solution introduced is greater than or desirable glass polishing properties are imparted to the equal to the number of equivalents of cerium introduced subject compositions by inclusion therein of the simultaneously. It may be advantageous to use a greater Ln2-xCex.Si2O7 phase. O than 5% excess of equivalents of base with respect to By the term "glass" as utilized herein, there are in the equivalents of cerium. The pH of the reaction me tended not only glass and ceramics, but also the other dium may range from 5 to 10. It advantageously ranges materials of vitreous type. from 7 to 9. It may be especially advantageous to con The present invention also features a novel process trol the pH at a constant value within +0.1 pH unit. for the preparation of the subject compositions, said 15 The aqueous solution of the salt of at least one triva process comprising: lent rare earth or yttrium must be soluble under the (i) simultaneously mixing a solution of a cerium salt, a operating conditions of the process of the invention. basic solution, an aqueous solution of a salt of at least Exemplary of suitable salts, representative are the chlo one trivalent rare earth or of yttrium, and a solution of rides or nitrates of lanthanum, cerium, praseodymium, at least one oxide derivative of silicon capable of form- 20 neodymium, samarium, europium, gadolinium, terbium, ing insoluble rare earth compounds; dysprosium, holmium, erbium, thulium, ytterbium, lute (ii) filtering the precipitate which results; and cium, and of yttrium.
Load more

Recommended publications
  • Fabrication and Characterization of Rare-Earth Silicide Thin Films
    UNIVERSITÉ CATHOLIQUE DE LOUVAIN Ecole Polytechnique de Louvain ICTEAM Fabrication and characterization of rare-earth silicide thin films Dissertation présentée en vue de l’obtention du grade de Docteur en Sciences de l’Ingénieur par Nicolas Reckinger Promoteurs: Prof. Vincent Bayot Prof. Jean-Pierre Raskin Février 2011 UNIVERSITÉ CATHOLIQUE DE LOUVAIN Ecole Polytechnique de Louvain ICTEAM Fabrication and characterization of rare-earth silicide thin films Dissertation présentée en vue de l’obtention du grade de Docteur en Sciences de l’Ingénieur par Nicolas Reckinger Membres du jury: Prof. Vincent Bayot, promoteur Prof. Jean-Pierre Raskin, promoteur Prof. Emmanuel Dubois Prof. Denis Flandre Dr. Thierry Baron Prof. Siegfried Mantl Dr. Xiaohui Tang Prof. Danielle Vanhoenacker-Janvier, président Février 2011 Abstract With the continuous reduction of the dimensions of metal-oxide- semiconductor field-effect transistors (MOSFET), issues related to the formation of source and drain contacts by ion implantation appear. A new source and drain architecture based on metallic contacts over silicon was proposed to replace conventional highly doped extensions. To real- ize such a device, the so-called Schottky barrier (SB) MOSFET, requires working with materials presenting low Schottky barrier heights (SBH) to silicon. For n-type MOSFETs, rare-earth silicides, alloys between silicon and a rare-earth metal, are the best candidates. For Schottky barrier MOSFETs to compete with conventional ones in terms of on- and off- currents, the SBH of rare-earth silicides is intrinsically still too high and must accordingly be further reduced. Such a barrier decrease can be achieved with the dopant segregation technique, where a thin dopant layer is interposed between the silicide and silicon.
    [Show full text]
  • ACCGE 2015 Abstracts Ebook
    Table of Contents Introduction/Plenary Correlated Electron Crystals 1 Detector Materials: Scintillators and Semiconductors (ACCGE) 1 Fundamentals of Crystal Growth (ACCGE) 1 III-V Nitride, SiC, and Other Wide Bandgap Materials (Joint ACCGE/OMVPE) 1 Second Symposium on 2D Electronic Materials (Joint ACCGE/OMVPE) 1 Correlated Electron Crystals 2 Detector Materials: Scintillators and Semiconductors (ACCGE) 2 Fundamentals of Crystal Growth (ACCGE) 2 III-V Nitride, SiC, and Other Wide Bandgap Materials (Joint ACCGE/OMVPE) 2 Second Symposium on 2D Electronic Materials (Joint ACCGE/OMVPE) 2 Detector Materials: Scintillators and Semiconductors (ACCGE) 3 Fundamentals of Crystal Growth (ACCGE) 3 III-V Nitride, SiC, and Other Wide Bandgap Materials (Joint ACCGE/OMVPE) 3 Second Symposium on 2D Electronic Materials (Joint ACCGE/OMVPE) 3 Poster Session 1 III-Vs on Silicon (Joint ACCGE/OMVPE) 1 Young Author and AACG Awards Detector Materials: Scintillators and Semiconductors (ACCGE) 4 Fundamentals of Crystal Growth (ACCGE) 4 III-Vs on Silicon (Joint ACCGE/OMVPE) 2 Second Symposium on 2D Electronic Materials (Joint ACCGE/OMVPE) 4 III-V Nitride, SiC, and Other Wide Bandgap Materials (Joint ACCGE/OMVPE) 4 Nonlinear Optical and Laser Host Materials (ACCGE) 1 Thin Film Growth, Epitaxy, and Superlattices (Joint ACCGE/OMVPE) 1 Second Symposium on 2D Electronic Materials (Joint ACCGE/OMVPE) 5 III-V Nitride, SiC, and Other Wide Bandgap Materials (Joint ACCGE/OMVPE) 5 Materials for Photovoltaics and Energy Technology (Joint ACCGE/OMVPE) 1 Nonlinear Optical and
    [Show full text]
  • Hydrothermal Crystal Growth of Metal Borates for Optical Applications Carla Heyward Clemson University, [email protected]
    Clemson University TigerPrints All Dissertations Dissertations 8-2013 Hydrothermal Crystal Growth of Metal Borates for Optical Applications Carla Heyward Clemson University, [email protected] Follow this and additional works at: https://tigerprints.clemson.edu/all_dissertations Part of the Chemistry Commons Recommended Citation Heyward, Carla, "Hydrothermal Crystal Growth of Metal Borates for Optical Applications" (2013). All Dissertations. 1164. https://tigerprints.clemson.edu/all_dissertations/1164 This Dissertation is brought to you for free and open access by the Dissertations at TigerPrints. It has been accepted for inclusion in All Dissertations by an authorized administrator of TigerPrints. For more information, please contact [email protected]. HYDROTHERMAL CRYSTAL GROWTH OF METAL BORATES FOR OPTICAL APPLICATIONS A Dissertation Presented to the Graduate School of Clemson University In Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy Chemistry by Carla Charisse Heyward August 2013 Accepted by: Dr. Joseph Kolis, Committee Chair Dr. Shiou-Jyh Hwu Dr. Andrew Tennyson Dr. Gautam Bhattacharyya ABSTRACT Crystals are the heart of the development of advance technology. Their existence is the essential foundation in the electronic field and without it there would be little to no progress in a variety of industries including the military, medical, and technology fields. The discovery of a variety of new materials with unique properties has contributed significantly to the rapidly advancing solid state laser field. Progress in the crystal growth methods has allowed the growth of crystals once plagued by difficulties as well as the growth of materials that generate coherent light in spectral regions where efficient laser sources are unavailable. The collaborative progress warrants the growth of new materials for new applications in the deep UV region.
    [Show full text]
  • Crystal Growth of Quantum Magnets in the Rare-Earth Pyrosilicate Family R2si2o7 (R = Yb, Er) Using the Optical Floating Zone Method
    crystals Article Crystal Growth of Quantum Magnets in the Rare-Earth Pyrosilicate Family R2Si2O7 (R = Yb, Er) Using the Optical Floating Zone Method Harikrishnan S. Nair 1,2, Tim DeLazzer 1, Tim Reeder 1, Antony Sikorski 1, Gavin Hester 1 and Kate A. Ross 1,* 1 Department of Physics, Colorado State University, 200 W. Lake St., Fort Collins, CO 80523-1875, USA; [email protected] (T.D.); [email protected] (T.R.); [email protected] (A.S.); [email protected] (G.H.) 2 Department of Physics, 500 W. University Ave, The University of Texas at El Paso, El Paso, TX 79968, USA; [email protected] * Correspondence: [email protected]; Tel.: +1-970-491-5370 Received: 23 March 2019; Accepted: 2 April 2019; Published: 7 April 2019 Abstract: We report on the crystal growth of rare-earth pyrosilicates, R2Si2O7 for R = Yb and Er using the optical floating zone method. The grown crystals comprise members from the family of pyrosilicates where the rare-earth atoms form a distorted honeycomb lattice. C-Yb2Si2O7 is a quantum dimer magnet with field-induced long range magnetic order, while D-Er2Si2O7 is an Ising-type antiferromagnet. Both growths resulted in multi-crystal boules, with cracks forming between the different crystal orientations. The Yb2Si2O7 crystals form the C-type rare-earth pyrosilicate structure with space group C2/m and are colorless and transparent or milky white, whereas the Er-variant 3+ is D-type, P21/b, and has a pink hue originating from Er . The crystal structures of the grown single crystals were confirmed through a Rietveld analysis of the powder X-ray diffraction patterns from pulverized crystals.
    [Show full text]
  • Standard X-Ray Diffraction Powder Patterns
    E^l Admin. NBS MONOGRAPH 25—SECTION 5 Refecii^M not to be ^ferlrom the library. Standard X-ray Diffraction Powder Patterns ^\ / U.S. DEPARTMENT OF COMMERCE S NATIONAL BUREAU OF STANDARDS THE NATIONAL BUREAU OF STANDARDS The National Bureau of Standards^ provides measurement and technical information services essential to the efficiency and effectiveness of the work of the Nation's scientists and engineers. The Bureau serves also as a focal point in the Federal Government for assuring maximum application of the physical and engineering sciences to the advancement of technology in industry and commerce. To accomplish this mission, the Bureau is organized into three institutes covering broad program areas of research and services: THE INSTITUTE FOR BASIC STANDARDS . provides the central basis within the United States for a complete and consistent system of physical measurements, coordinates that system with the measurement systems of other nations, and furnishes essential services leading to accurate and uniform physical measurements throughout the Nation's scientific community, industry, and commerce. This Institute comprises a series of divisions, each serving a classical subject matter area: —Applied Mathematics—Electricity—Metrology—Mechanics—Heat—Atomic Physics—Physical Chemistry—Radiation Physics— -Laboratory Astrophysics^—Radio Standards Laboratory,^ which includes Radio Standards Physics and Radio Standards Engineering—Office of Standard Refer- ence Data. THE INSTITUTE FOR MATERIALS RESEARCH . conducts materials research and provides associated materials services including mainly reference materials and data on the properties of ma- terials. Beyond its direct interest to the Nation's scientists and engineers, this Institute yields services which are essential to the advancement of technology in industry and commerce.
    [Show full text]
  • Standard X-Ray Diffraction Powder Patterns
    NBS MONOGRAPH 25—SECTION 4 Standard X-ray Diffraction Powder Patterns U.S. DEPARTMENT OF COMMERCE NATIONAL BUREAU OF STANDARDS THE NATIONAL BUREAU OF STANDARDS The National Bureau of Standards is a principal focal point in the Federal Government for assuring maximum application of the physical and engineering sciences to the advancement of technology in industry and commerce. Its responsibilities include development and mainte- nance of the national standards of measurement, and the provisions of means for making measurements consistent with those standards; determination of physical constants and properties of materials; development of methods for testing materials, mechanisms, and structures, and making such tests as may be necessary, particularly for government agencies; cooperation in the establishment of standard practices for incorporation in codes and specifi- cations advisory service to government agencies on scientific and technical problems ; invention ; and development of devices to serve special needs of the Government; assistance to industry, business, and consumers m the development and acceptance of commercial standards and simplified trade practice recommendations; administration of programs in cooperation with United States business groups and standards organizations for the development of international standards of practice; and maintenance of a clearinghouse for the collection and dissemination of scientific, technical, and engineering information. The scope of the Bureau's activities is suggested in the following listing of its three Institutes and their organizatonal units. Institute for Basic Standards. Applied Mathematics. Electricity. Metrology. Mechanics. Heat. Atomic Physics. Physical Chemistry. Laboratory Astrophysics.* Radiation Phys- ics. Radio Standards Laboratory:* Radio Standards Physics; Radio Standards Engineering. Office of Standard Reference Data. Institute for Materials Research.
    [Show full text]
  • (58) Field State St. Such It." R Germanate, Zinc Gallate, Calcium Magnesium Pyrosilicate, Pp P Ry
    USOO752.5094B2 12) United States Patent 10) Patent No.: US 7.525,0949 9 B2 Cooke et al. (45) Date of Patent: Apr. 28, 2009 (54) NANOCOMPOSITE SCINTILLATOR, 5,264,154. A 1 1/1993 Akiyama et al. DETECTOR, AND METHOD 5,952,665 A 9/1999 Bhargava 6,207,077 B1 3/2001 Burnell-Jones (75) Inventors: D. Wayne Cooke, Santa Fe, NM (US); 6,323,489 B1 11/2001 McClellan Edward A. McKigney, Los Alamos, 6,448,566 B1 9, 2002 Riedner et al. NM (US); Ross E. Muenchausen, Los -3. W - R ck 239: SRuffet etal. al. ................... 428/402 Alamos, NM (US); Bryan L. Bennett, 6,599.444 B2 7/2003 Burnell-Jones Los Alamos, NM (US) 6,689,293 B2 2/2004 McClellan et al. 6,699.406 B2 3/2004 Riman et al. (73) Assignee: Los Alamos National Security, LLC, 6,734,465 B1 5, 2004 Taskar et al. Los Alamos, NM (US) 7,094,361 B2 8/2006 Riman et al. 7,145,149 B2 12/2006 Cooke et al. (*) Notice: Subject to any disclaimer, the term of this 2004/0174917. A 9 2004 Riman et al. patent is extended or adjusted under 35 2006/0231797 A1 10, 2006 Riman et al. U.S.C. 154(b) by 0 days. OTHER PUBLICATIONS (21) Appl. No.: 11/644,246 Shah et al., “CeBr3 Scintillators for Gamma-Ray Spectroscopy.” IEEE Transactions on Nuclear Science, vol. 52, No. 6, Dec. 2005, pp. (22) Filed: Dec. 21, 2006 3157-3159. Glodo et al., “Thermoluminescence of LaBr3:Ce and LaCl3:Ce crys (65) Prior Publication Data tals.” Nuclear Instruments and Methods in Physics Research A537 (2005) pp.
    [Show full text]
  • (12) United States Patent (10) Patent No.: US 6,437,336 B1 Pauwels Et Al
    USOO6437336B1 (12) United States Patent (10) Patent No.: US 6,437,336 B1 Pauwels et al. (45) Date of Patent: Aug. 20, 2002 (54) SCINTILLATOR CRYSTALS AND THEIR 4,473.513 A 9/1984 Cusano et al. ............... 264/1.2 APPLICATIONS AND MANUEACTURING 4,525,628 A 6/1985 DiBianca et al. ........... 250/367 PROCESS 4,783,596 A 11/1988 Riedner et al. .......... 250/483.1 4,958,080 A 9/1990 Melcher .................. 250/483.1 5,660,627 A 8/1997 Manente et al. .............. 117/13 (75) Inventors: Damien Pauwels, Evry; Bruno Viana, 6,093,347 A 7/2000 Lynch et al. ............. 252/301.4 Montgeron; Andree Kahn-Harari, Paris, all of (FR); Pieter Dorenbos, OTHER PUBLICATIONS GM Rijswijk; Carel Wilhelm Eduard Lempicki, A. et al., “Ce-doped scintillators: LSO and Van Eijk, LS Delft, both of (NL) LuAP” Nuclear Instruments and Methods in Physics Research A416, pp. 333-344, 1998. (73) Assignee: Crismatec (FR) Saoudi, A. et al., “IEEE Transactions on Nuclear Science.” (*) Notice: Subject to any disclaimer, the term of this 46:6, pp. 1925–1928, 1999. patent is extended or adjusted under 35 Primary Examiner-Georgia Epps U.S.C. 154(b) by 0 days. Assistant Examiner Richard Hanig (74) Attorney, Agent, or Firm-Pennie & Edmonds LLP (21) Appl. No.: 09/686,972 (57) ABSTRACT (22) Filed: Oct. 12, 2000 A monoclinic Single crystal with a lutetium pyrosilicate Related U.S. Application Data structure is described. The crystal is formed by crystalliza (60) Provisional application No. 60/225,400, filed on Aug. 15, tion from a congruent molten composition of LU2-M.
    [Show full text]
  • Standard X-Ray Diffraction Powder Patterns
    NBS MONOGRAPH 25— SECTION 2 Standard X-ray Diffraction Powder Patterns U.S. DEPARTMENT OF COMMERCE NATIONAL BUREAU OF STANDARDS THE NATIONAL BUREAU OF STANDARDS Functions and Activities The functions of the National Bureau of Standards are set forth in the Act of Congress, March 3, 1901, as amended by Congress in Public Law 619, 1950. These include the development and maintenance of the national standards of measurement and the provision of means and methods for making measurements consistent with these standards; the determination of physical constants and properties of materials; the development of methods and instruments for testing materials, devices, and structures; advisory services to government agencies on scientific and technical problems; invention and development of devices to serve special needs of the Government; and the development of standard practices, codes» and specifications. The work includes basic and applied research, development, engineering, instrumentation, testing, evaluation, calibration services, and various consultation and information services. Research projects are also performed for other government agencies when the work relates to and supplements the basic program of the Bureau or when the Bureau's unique competence is required. The scope of activities is suggested by the listing of divisions and sections on the inside of the back cover. Publications The results of the Bureau's research are published either in the Bureau's own series of publications or in the journals of professional and scientific societies. The Bureau itself publishes three periodicals available from the Government Printing Office: The Journal of Research, published in four separate sections, presents complete scientific and technical papers ; the Technical News Bulletin presents summary and preliminary reports on work in progress ; and Central Radio Propagation Laboratory Ionospheric Predictions provides data for determining the best frequencies to use for radiocom- munications throughout the world.
    [Show full text]
  • Investigation of Rare-Earth Alumino-Silicate Refractories for Molten Aluminum Alloy Containment Michael Hughes O'brien Iowa State University
    Iowa State University Capstones, Theses and Retrospective Theses and Dissertations Dissertations 1988 Investigation of rare-earth alumino-silicate refractories for molten aluminum alloy containment Michael Hughes O'Brien Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/rtd Part of the Materials Science and Engineering Commons Recommended Citation O'Brien, Michael Hughes, "Investigation of rare-earth alumino-silicate refractories for molten aluminum alloy containment " (1988). Retrospective Theses and Dissertations. 9707. https://lib.dr.iastate.edu/rtd/9707 This Dissertation is brought to you for free and open access by the Iowa State University Capstones, Theses and Dissertations at Iowa State University Digital Repository. It has been accepted for inclusion in Retrospective Theses and Dissertations by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. INFORMATION TO USERS The most advanced technology has been used to photo­ graph and reproduce this manuscript from the microfilm master. UMI films the original text directly from the copy submitted. Thus, some dissertation copies are in typewriter face, while others may be from a computer printer. In the unlikely event that the author did not send UMI a complete manuscript and there are missing pages, these will be noted. Also, if unauthorized copyrighted material had to be removed, a note will indicate the deletion. Oversize materials (e.g., maps, drawings, charts) are re­ produced by sectioning the original, beginning at the upper left-hand comer and continuing from left to right in equal sections with small overlaps. Each oversize page is available as one exposure on a standard 35 mm slide or as a 17" x 23" black and white photographic print for an additional charge.
    [Show full text]
  • Dr. Shreeniwas K. Omanwar Major Nominations and Achievements During Last 5 Years. High Lights- Academic Record
    BIO-DATA SANT GADGE BABA AMRAVATI UNIVERSITY DEPARTMENT OF PHYSICS Dr. Shreeniwas K. Omanwar Higher Grade Professor (HAG-Scale) & Head, Department of Physics Co-ordinator, Patent Cell, SGBAU, Amravati Co-ordinator, Swami Vivekanand Studies Centre, Co-ordinator, UGC-ESS (SC/ST, Mino & OBC) Near Tapowan, Sant Gadge Baba Amravati University, Amravati (M. S.) PIN Code: 444 602 Residence 104-B, Saibhakti Appartments, Samartha Colony, Amravati (M.S.) PIN Code: 444606 [email protected], E-mail: [email protected] [email protected] +91-721-2662279 EXT(O): 269 +91 9422856844 (Cell) Tel No +91 -721-2676100 (R) Fax No +91-721-2662135,2660949 Date of Birth: 1st July 1959 Major nominations and achievements during last 5 years. Professor B. T. Deshmukh Research Award for outstanding contribution to Luminescence and extension of the research work. Awarded by LSI, India (18-2- 2016 at NCLA-2016. Fellow of Maharashtra Academy of Sciences – 2015(Fellowship No. ALF-1010 30- 10-2015) Member of International Advisory Committee, CIMTEC 2016-IAB Symp. D,June 5- 10, Perugia, Italy (Smart and Multifunctional Materials, Devices and Structures) LMC Member (Expert-Member), Shivshakti Shikshan Santha’s College of Arts, Science and Commerce Babhulgaon.(18-3-2014) Nominated as Vice President of LSI (Maharashtra Chapter) BARC, DAE, Mumbai(25- 11-2011) Chairman, Inclusive Inovations-2013, SGBAU, Amravati Chairman, Patent Cell, SGBAU, Amravati.(2012-till date) Member of Advisory Committee RDTAC, Nagpur, Govt. of India 2014-17) Member, Editorial Board Nominated by Governor of the State (Three Consecutive Terms, 2000-2010) Govt. of Maharashtra Gazetteer Department. Member of IQAC, SGBAU, Amravati & Ex-Director, IQAC, SGBAU, Amravati High Lights- Academic Record 1 Throughout FIRST CLASS with DISTINCTION (X, XII, B.Sc.
    [Show full text]
  • Crystal Growth and Optical Properties of Ce-Doped (La,Y)2Si2o7 Single Crystal
    Crystal growth and optical properties of Ce-doped (La,Y)2Si2O7 single crystal Takahiko Horiai1,*, Juraj Paterek1, Jan Pejchal1, Marketa Jarosova1, Jan Rohlicek1, Shunsuke Kurosawa2,3, Takashi Hanada2, Masao Yoshino2, Akihiro Yamaji2,3, Satoshi Toyoda2,3, Hiroki Sato2,3, Yuji Ohashi2,3, Kei Kamada3,4, Yuui Yokota2, Akira Yoshikawa2,3,4, and Martin Nikl1 1 Institute of Physics, Czech Academy of Sciences, Cukrovarnicka 10, Prague, Czech Republic 2 Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Sendai, Japan 3 New Industry Creation Hatchery Center, Tohoku University, 6-6-10 Aoba, Sendai, Japan 4 C&A corporation, 1-16-23 Ichibancho, Sendai, Japan *E-mail: [email protected] Abstract We have grown Ce-doped (La,Y)2Si2O7 single crystal by micro-pulling-down method and investigated its optical and scintillation properties. We have successfully prepared the single crystal with (Ce0.015La0.600Y0.385)2Si2O7 composition. The observed thermal quenching process could be characterized by the quenching temperature (T50%) of 526 K and its activation energy was determined to be 0.62 eV. Further considering the thermal quenching factors, it was found that the thermal quenching was caused by at least the thermal ionization and maybe also by classical thermal quenching. The light output and scintillation decay time were evaluated to be ~12,000 photons/MeV and ~42 ns, respectively. These results indicate that (Ce0.015La0.600Y0.385)2Si2O7 has a great potential for application in scintillation materials. Keywords A2. Growth from melt; Seed crystals; Single crystal growth; B1. Oxides; B2. Scintillator materials Introduction Scintillation crystals convert energy of ionizing radiation to ultra-violet or visible light, and are widely used in radiation detector applications such as oil well logging, medical imaging and high energy physics [1-5].
    [Show full text]