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Sample records for beryllia

  1. Kinetic analysis of interstitial atomic hydrogen in a-Si:(H,O,N) and beryllia

    International Nuclear Information System (INIS)

    A method for interpreting thermal decay of interstitial atomic hydrogen Hoi produced by irradiation in a-Si: (H,O,N) and in beryllia was developed. The hypothesis of Hoi were produced from RH type molecules by irradiation effect and trapped in the interstitials of studied elements was considered. The hypothesis of the heating causes the disarming of Hoi, and can be retrapped, recombine with R matrices or react between themselves to form the H2 molecules. The kinetic equations were arranged by a schematic method for each proposed reaction. These equations were solved numerically by RungeKutta method. The adjust parameters show that the Hoi + Hoi -> H2 occurs only for beryllia, because the kinetic occurs at higher temperatures. All the parameters were adjusted to Arrhenius law, allowing to determine the activation energies for each process. (M.C.K.)

  2. Effect of beryllia substitution and addition in a YBa2Cu3O7-δ compound

    International Nuclear Information System (INIS)

    The effect of BeO substitution and addition in the superconducting properties of YBa2Cu3O7-δ superconductors has been investigated by temperature resistance measurements and x-ray diffraction studies. The results revealed that the substitution or addition of BeO in YBa2Cu3O7-δ does not have much detrimental effect on the superconducting properties. Because of this nonpoisoning behavior, beryllia is suggested as a suitable substrate material for the production of superconducting thin films

  3. Study on the bound water of several high specific surface-area oxides (beryllia, alumina, silica-alumina)

    International Nuclear Information System (INIS)

    This study is concerned with the bound water of several oxides (beryllia, alumina, silica-alumina) at different steps of their dehydration (heating temperatures between 150 and 1100 deg. C). The following techniques have been used simultaneously: Thermal analysis (a new method has been developed), nitrogen adsorption (study of the texture), Diborane hydrolysis (qualitative and quantitative analysis of surface water), Infra-red spectrography (in the absorption range of water), Nuclear magnetic resonance (in the resonance range of protons). Thanks to these different techniques, five kinds of bound water have been observed. Attention is called on the great influence of the thermal treatment conditions on the evolution of the products resulting from the decomposition of alumina α-trihydrate Al(OH)3 and beryllium α-hydroxide, in the course of the dehydration. Moreover, the author emphasizes the peculiar properties of the two kinds of oxides (alumina and beryllia) prepared through a new method of treatment under low pressure and constant speed of decomposition. Such particular features concern mainly texture, bound water, and consequently, also catalytic activity. (author)

  4. Study on the bound water of several high specific surface-area oxides (beryllia, alumina, silica-alumina); Etude de l'eau de constitution de plusieurs oxydes a grande surface specifique (glucine, alumine, silice-alumine)

    Energy Technology Data Exchange (ETDEWEB)

    Rouquerol, J. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1964-11-01

    This study is concerned with the bound water of several oxides (beryllia, alumina, silica-alumina) at different steps of their dehydration (heating temperatures between 150 and 1100 deg. C). The following techniques have been used simultaneously: Thermal analysis (a new method has been developed), nitrogen adsorption (study of the texture), Diborane hydrolysis (qualitative and quantitative analysis of surface water), Infra-red spectrography (in the absorption range of water), Nuclear magnetic resonance (in the resonance range of protons). Thanks to these different techniques, five kinds of bound water have been observed. Attention is called on the great influence of the thermal treatment conditions on the evolution of the products resulting from the decomposition of alumina {alpha}-trihydrate Al(OH){sub 3} and beryllium {alpha}-hydroxide, in the course of the dehydration. Moreover, the author emphasizes the peculiar properties of the two kinds of oxides (alumina and beryllia) prepared through a new method of treatment under low pressure and constant speed of decomposition. Such particular features concern mainly texture, bound water, and consequently, also catalytic activity. (author) [French] Ce travail porte sur l'eau de constitution de plusieurs oxydes (glucine, alumine, silice-alumine) aux differents degres de leur deshydratation (temperatures de traitement comprises entre 150 et 1100 deg. C). Cette etude met simultanement en oeuvre: l'analyse thermique (proposition d'une nouvelle methode), l'adsorption d'azote (etude de texture), l'hydrolyse du diborane (analyse qualitative et quantitative de l'eau de surface), la spectrographie infra-rouge (dans le domaine d'absorption de l'eau), la resonance magnetique nucleaire (dans le domaine de resonance des protons). A l'aide de ces differentes techniques, cinq formes d'eau de constitution ont ete observees. L'attention est attiree sur la tres grande influence

  5. Ab-initio investigations of the electronic properties of bulk wurtzite Beryllia and its derived nanofilms

    KAUST Repository

    Goumri-Said, Souraya

    2010-08-01

    In this Letter we investigate the electronic properties of the bulk and the nanofilm BeO in wurtzite structure. We performed a first-principles pseudo-potential method within the generalized gradient approximation. We will give more importance to the changes in band structure and density of states between the bulk structure and its derived nanofilms. The bonding characterization will be investigated via the analysis Mulliken population and charge density contours. It is found that the nanofilm retains the same properties as its bulk structure with slight changes in electronic properties and band structure which may offer some unusual transport properties. © 2010 Elsevier B.V. All rights reserved.

  6. Beryllium. Beryllium oxide, obtention and properties. Pt.4

    International Nuclear Information System (INIS)

    As a continuation of the 'Beryllium' series this work reviews several methods of high purity beryllia production. Diverse methods of obtention and purification from different beryllium compounds are described. Some chemical, mechanical and electrical properties related with beryllia obtention methods are summarized. (Author)

  7. Thermal-shock Resistance of a Ceramic Comprising 60 Percent Boron Carbide and 40 Percent Titanium Diboride

    Science.gov (United States)

    Yeomans, C M; Hoffman, C A

    1953-01-01

    Thermal-shock resistance of a ceramic comprising 60 percent boron carbide and 40 percent titanium diboride was investigated. The material has thermal shock resistance comparable to that of NBS body 4811C and that of zirconia, but is inferior to beryllia, alumina, and titanium-carbide ceramals. It is not considered suitable for turbine blades.

  8. A measurement of the response to fast neutrons of several materials dosemeters

    International Nuclear Information System (INIS)

    The response to fast neutrons was measured for three types of materials testing dosemeters: fast neutron dosimetry silicon diodes; beryllia, alumina and calcium fluoride TLDs; graphite walled ionisation chambers. The calibrations were made using a 3MW positive ion accelerator. The arrangement of the target, beam monitor and devices is described, and the measured fast neutron sensitivities are presented. (UK)

  9. Pulsed laser deposition of epitaxial BeO thin films on sapphire and SrTiO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Peltier, Thomas; Takahashi, Ryota; Lippmaa, Mikk, E-mail: mlippmaa@issp.u-tokyo.ac.jp [Institute for Solid State Physics, University of Tokyo, Chiba 277-8581 (Japan)

    2014-06-09

    Epitaxial beryllia thin films were grown by pulsed laser deposition on Al{sub 2}O{sub 3}(001) and SrTiO{sub 3}(111) substrates. Nearly relaxed epitaxial films were obtained on both substrates at growth temperatures of up to about 600 °C. Crystalline films with expanded lattice parameters were obtained even at room temperature. The maximum growth temperature was limited by a loss of beryllium from the film surface. The volatility of beryllium appeared to be caused by the slow oxidation kinetics at the film surface and the re-sputtering effect of high-energy Be and BeO species in the ablation plume. Time-of-flight plume composition analysis suggested that the target surface became Be metal rich at low oxygen pressures, reducing the growth rate of beryllia films.

  10. Spray drying of beryllium oxide powder

    International Nuclear Information System (INIS)

    Forming of beryllia ceramics through dry pressing requires the agglomeration of the powder through spray drying. To produce high quality fired ceramics it is necessary to disperse/grind the primary powder prior to binder addition. Size reduction of the powder is accomplished using an aqueous system in Vibro-Energy mills (VEM) charged with beryllia media to minimize contamination. Two VEM mills of different size were used to characterize the grinding operation. Details of the grinding kinetics are described within the context of the Macroscopic Population Balance Model approach. Spray drying of the ceramic slurry was accomplished with both a centrifugal atomizer and a two fluid nozzle atomizer. Two different spray dryers were used. Important operating parameters affecting the size distribution of the spray dried powder are discussed

  11. Complex dielectric constants for selected near-millimeter-wave materials at 245 GHz

    Science.gov (United States)

    Dutta, J. M.; Jones, C. R.; Dave, H.

    1986-01-01

    A double-beam instrument developed in this laboratory has been used to measure the complex dielectric constant of selected materials at 245 GHz. It is reported here the results for crystalline quartz, fused silica (Spectrosil WF and Dynasil 4000), beryllia (iso-pressed), boron nitride (hot-pressed), and a nickel ferrite (Trans-Tech 2-111). Results are compared with the data obtained by other researchers.

  12. Beryllium facilities in India

    International Nuclear Information System (INIS)

    Due to its unique combination of physical, mechanical, thermal and nuclear properties, beryllium is indispensable for many applications in the fields of nuclear and space sciences. Beryllia and copper beryllium alloys have also found extensive applications in the electrical and electronic industries. Beryllium facilities at Bhabha Atomic Research Centre (BARC) have been set up to meet indigenous requirements for these materials. Besides developing beryllium technology, the project team has also designed and developed a number of special purpose equipment. (Author)

  13. Annual report of the Metallurgy Division - period ending December 1975

    International Nuclear Information System (INIS)

    The R and D activities of the Metallurgy Division of the Bhabha Atomic Research Centre, Bombay (India) during 1975 are described. Some of the R and D programmes of particular interest to nuclear technology are: (1) flowsheet development for the production of rare metals and alloys of nuclear use e.g. hafnium, beryllium, zirconium (2) metallurgical, irradiation hardening and corrosion studies on Zr and Zr-base alloys and (3) studies of nuclear ceramic materials such as UO2 and beryllia. (M.G.B.)

  14. Millimeter-wave properties of neutron-irradiated ceramics for RF-window MFE applications

    International Nuclear Information System (INIS)

    In response to materials needs connected with electron cyclotron resonance heating (ECRH) in magnetic fusion energy (MFE) reactors, the facility at Los Alamos for dielectric properties measurements on irradiated materials was upgraded to include a capability in the millimeter-wave region. With it, dielectric constants (K) and loss tangents (tandelta) were measured at frequencies (f) of about 95 GHz for polycrystalline alumina and beryllia specimens inserted into WR-10 waveguide after irradiations in EBR-II at 3850C and an average fluence of 8 x 1025 n/cm2 (E > 0.1 MeV). Relative to annealed controls, the dielectric loss quantity Ktandelta doubled for both ceramic types. Furthermore, the BeO material underwent substantial enough changes in K and mass density rho to indicate the likelihood of millimeter-window thickness detuning

  15. Oxide Fiber Targets at ISOLDE

    CERN Document Server

    Köster, U; Carminati, D; Catherall, R; Cederkäll, J; Correia, J G; Crepieux, B; Dietrich, M; Elder, K; Fedosseev, V; Fraile-Prieto, L M; Franchoo, S; Fynbo, H O U; Georg, U; Giles, T; Joinet, A; Jonsson, O C; Kirchner, R; Lau, C; Lettry, Jacques; Maier, H J; Mishin, V I; Oinonen, M; Peräjärvi, K; Ravn, H L; Rinaldi, T; Santana-Leitner, M; Wahl, U; Weissman, L

    2003-01-01

    Many elements are rapidly released from oxide matrices. Some oxide powder targets show a fast sintering, thus losing their favorable release characteristics. Loosely packed oxyde fiber targets are less critical since they may maintain their open structure even when starting to fuse together at some contact points. The experience with various oxyde fiber targets (titania, zirconia, ceria and thoria) used in the last years at ISOLDE is reviewed. For short-lived isotopes of Cu, Ga and Xe the zirconia and ceria targets respectively provided significantly higher yields than any other target (metal foils, oxide powders, etc.) tested before. Titania fibers, which were not commercially available, were produced in a relic process by impregnation of a rayon felt in a titanium chloride solution and subsequent calcination by heating the dried felt in air. Thoria fibers were obtained either by the same process or by burning commercial gas lantern mantle cloth. In the future a beryllia fiber target could be used to produce...

  16. Aluminium nitride: from the powder to the substrate. Le nitrure d'aluminium: de la poudre au substrat

    Energy Technology Data Exchange (ETDEWEB)

    Jarrige, J. (Lab. de Ceramiques Nouvelles, Limoges (France)); Mexmain, J. (Lab. de Ceramiques Nouvelles, Limoges (France)); Oumaloul, M. (Lab. de Ceramiques Nouvelles, Limoges (France)); Bachelard, R. (CRRA ELF ATOCHEM, Pierre Benite (France)); Disson, J.P. (CRRA ELF ATOCHEM, Pierre Benite (France))

    1993-04-01

    The aluminium nitride is a material which should replace alumina or beryllia as substrate for power electronic applications. The powder, prepared by carbothermal nitridation, is dispersed in a butanone-2-ethanol azeotrop solvent with a phosphate ester. Electrical conductivity, sedimentation, viscosity have been used to determine which phenomena take place in the defloculation of the suspension. The stability of AlN suspensions is due mainly to an electrostatic mechanism, with a steric contribution. The aluminium nitride tape-casting slip has been sintered at 1850 C in a nitrogen atmosphere. Removing of the binder and plasticizer can be performed in the same oven at 650 C, due to their nature and low concentration. The thermal conductivity of the substrates has been measured and is in the 160 to 200 W/m.K range. (orig.).

  17. A 240-channel thick film multi-chip module for readout of silicon drift detectors

    Science.gov (United States)

    Lynn, D.; Bellwied, R.; Beuttenmueller, R.; Caines, H.; Chen, W.; DiMassimo, D.; Dyke, H.; Elliott, D.; Grau, M.; Hoffmann, G. W.; Humanic, T.; Jensen, P.; Kleinfelder, S. A.; Kotov, I.; Kraner, H. W.; Kuczewski, P.; Leonhardt, B.; Li, Z.; Liaw, C. J.; LoCurto, G.; Middelkamp, P.; Minor, R.; Mazeh, N.; Nehmeh, S.; O'Conner, P.; Ott, G.; Pandey, S. U.; Pruneau, C.; Pinelli, D.; Radeka, V.; Rescia, S.; Rykov, V.; Schambach, J.; Sedlmeir, J.; Sheen, J.; Soja, B.; Stephani, D.; Sugarbaker, E.; Takahashi, J.; Wilson, K.; STAR-SVT Collaboration

    2000-01-01

    We have developed a thick film multi-chip module for readout of silicon drift (or low capacitance ˜200 fF) detectors. Main elements of the module include a custom 16-channel NPN-BJT preamplifier-shaper (PASA) and a custom 16-channel CMOS Switched Capacitor Array (SCA). The primary design criteria of the module were the minimizations of the power (12 mW/channel), noise (ENC=490 e - rms), size (20.5 mm×63 mm), and radiation length (1.4%). We will discuss various aspects of the PASA design, with emphasis on the preamplifier feedback network. The SCA is a modification of an integrated circuit that has been previously described [1]; its design features specific to its application in the SVT (Silicon Vertex Tracker in the STAR experiment at RHIC) will be discussed. The 240-channel multi-chip module is a circuit with five metal layers fabricated in thick film technology on a beryllia substrate and contains 35 custom and commercial integrated circuits. It has been recently integrated with silicon drift detectors in both a prototype system assembly for the SVT and a silicon drift array for the E896 experiment at the Alternating Gradient Synchrotron at the Brookhaven National Laboratory. We will discuss features of the module's design and fabrication, report the test results, and emphasize its performance both on the bench and under experimental conditions.

  18. Oxide fiber targets at ISOLDE

    Energy Technology Data Exchange (ETDEWEB)

    Koester, U. E-mail: ulli.koster@cern.ch; Bergmann, U.C.; Carminati, D.; Catherall, R.; Cederkaell, J.; Correia, J.G.; Crepieux, B.; Dietrich, M.; Elder, K.; Fedoseyev, V.N.; Fraile, L.; Franchoo, S.; Fynbo, H.; Georg, U.; Giles, T.; Joinet, A.; Jonsson, O.C.; Kirchner, R.; Lau, Ch.; Lettry, J.; Maier, H.J.; Mishin, V.I.; Oinonen, M.; Peraejaervi, K.; Ravn, H.L.; Rinaldi, T.; Santana-Leitner, M.; Wahl, U.; Weissman, L

    2003-05-01

    Many elements are rapidly released from oxide matrices. Some oxide powder targets show a fast sintering, thus losing their favorable release characteristics. Loosely packed oxide fiber targets are less critical since they may maintain their open structure even when starting to fuse together at some contact points. The experience with various oxide fiber targets (titania, zirconia, ceria and thoria) used in the last years at ISOLDE is reviewed. For short-lived isotopes of Cu, Ga and Xe the zirconia and ceria targets respectively provided significantly higher yields than any other target (metal foils, oxide powders, etc.) tested before. Titania fibers, which were not commercially available, were produced in a relic process by impregnation of a rayon felt in a titanium chloride solution and subsequent calcination by heating the dried felt in air. Thoria fibers were obtained either by the same process or by burning commercial gas lantern mantle cloth. In the future a beryllia fiber target could be used to produce very intense {sup 6}He beams (order of 10{sup 13} ions per second) via the {sup 9}Be(n,{alpha}) reaction using spallation neutrons.

  19. A 240-channel thick film multi-chip module for readout of silicon drift detectors

    International Nuclear Information System (INIS)

    We have developed a thick film multi-chip module for readout of silicon drift (or low capacitance ∼200 fF) detectors. Main elements of the module include a custom 16-channel NPN-BJT preamplifier-shaper (PASA) and a custom 16-channel CMOS Switched Capacitor Array (SCA). The primary design criteria of the module were the minimizations of the power (12 mW/channel), noise (ENC=490 e- rms), size (20.5 mmx63 mm), and radiation length (1.4%). We will discuss various aspects of the PASA design, with emphasis on the preamplifier feedback network. The SCA is a modification of an integrated circuit that has been previously described [1]; its design features specific to its application in the SVT (Silicon Vertex Tracker in the STAR experiment at RHIC) will be discussed. The 240-channel multi-chip module is a circuit with five metal layers fabricated in thick film technology on a beryllia substrate and contains 35 custom and commercial integrated circuits. It has been recently integrated with silicon drift detectors in both a prototype system assembly for the SVT and a silicon drift array for the E896 experiment at the Alternating Gradient Synchrotron at the Brookhaven National Laboratory. We will discuss features of the module's design and fabrication, report the test results, and emphasize its performance both on the bench and under experimental conditions