摘要:

High‐purity and high‐density tin dioxide doped with 1 × 1020/cm3antimony was prepared by hot isostatic pressing, and its electrical conductivity was measured over the temperature range 20° to 1200°C in various atmospheres. The conductivity decreased with increasing temperature and reached the value found in specimens normally sintered under the same conditions at normal pressure. The effect of microstructure on the carrier transport is discussed. Grain boundaries only slightly affect carrier transport at high temper

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1987.tb05688.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

The results of a transmission electron microscope study of the hydrothermal alteration products formed by perovskite and two titantate‐based “synroc” formulations are reported. It was found that perovskite, the host phase for strontium‐90, dissolved at combined temperatures and pressures greater than 110°C and 180 kPa. Dissolution of perovskite was accompanied by an epitaxial crystallization of the titanium dioxide polymorphs, brookite and anatase. Hollandite, which incorporates cesium‐137, dissolved more slowly than perovskite, with only minor TiO2crystallization. Intergrowths of zirconolite and zirkelite, the principal actinide‐containing phases, were highly resistant to hydrothermal treatments, maintaining their integrity under all experimenta

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1987.tb05689.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

The modified barium titanate ceramic Ba0.80Pb0.20(Ti0.88Zr0.12) O3doped with 0.8 mol% CaO and 1 mol%ZrO2was prepared. Investigation of the electrical and dielectric properties shows that the material has a room‐temperature dielectric constant of 3550 with a variation of 5.7% in the temperature range 10° to 60°C, a loss factor of 0.005, a dc resistivity 1.3 × 1012Ω‐cm, and a linear variation of resistivity in the log (resistivity) vs temperature plot. This material is a good choice for the fabrication of ceramic cap

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1987.tb05690.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

The kinetics of the initial stage of the formation of a nickel aluminate spinel on the surface of alumina substrates has been studied. The NiO layer was formed by evaporating a thin film Ni onto the surface of single‐crystal alumina substrates and oxidizing the specimens in air at 700°C. This method gave a thin layer of NiO film that was uniform in thickness on top of the alumina substrates. The alumina surfaces studied include (0001), [1120], [1102], and [1100]. After the initial oxidation, the samples were annealed in air at 1020°C. The interaction of the thin‐film and the single‐crystal substrates was examined using Rutherford back‐scattering spectroscopy. The crystallography of the alumina substrates was found to influence greatly the kinetics of the spinel formation. For example, the rate of the spinel formation reaction is fastest for the lsqb;1102rsqb; and lsqb;1100rsqb; orientations and slowest for the (0001) orientation. The roughness of the surface of the alumina substrate has also been shown to influence directly the rate of the spinel formation. The presence of surface scratches accelerated the spinel

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1987.tb05691.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

It is shown that according to the Adam‐Gibbs theory of viscosity the sign of the pressure dependence of viscosity is the same as the sign of the relaxational expansion coefficient. Existing data on systems where negative pressure dependence of viscosity has been observed and relaxational expansion coefficient values are available under the same temperature and pressure conditions appear to support this result. It is therefore suggested that the negative pressure dependence of viscosity and the negative relaxational expansion coefficient have a common mechanistic origin and that this result, in turn, supports the Adam‐Gibbs model of viscos

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1987.tb05692.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

The adhesion of an aluminum evaporation layer onto an alumina substrate was strong despite attack from the liquid gold‐silicon eutectic during an integrated circuit chip attachment process. Evidence of the resultant layer, which contained an oxygen concentration gradient from the interface into the Al, is presente

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1987.tb05693.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Mixtures of La2O3and Al2O3with various La contents were prepared by co‐precipitation from La(NO3)3and Al(NO3)3solutions and calcined at 800° to 1400°C. The addition of small amounts of La2O3(2 to 10 mol%) to Al2O3gives rise to the formation of lanthanum β‐alumina (La2O3·11–14Al2O3) upon heating to above 1000°C and retards the transformation of γ‐Al2O3to α‐Al2O3and asso

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1987.tb05694.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

The solid‐state reaction between yttrium oxide and amorphous silicon oxide with a molar ratio 1:1 has been studied. The effect of several flux materials on conversion at different temperatures (900° to 1300°C) has been investigated. Lithium compounds and especially fluoride gave the highest conversions. Fluorides of cations other than lithium were also powerful fluxes. The purity of the oxyorthosilicate formed was studied by different meth

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1987.tb05695.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

The metastable phase (δ‐phase) of SrCO3or BaCO3is obtained by quenching from the phase transition temperature of each carbonate for the admixture of a few mol% of BaSO4. The present paper concerns the δ‐phase formation process in the systems SrCO3‐BaSO4and BaCO3‐BaSO4by comparing the “dissolution” tendency of incorporated BaSO4in an aqueous suspension containing a cation‐exchange resin. A mixture of CaCO3and BaSO4was also examined for comparison as a system which does not participate in δ

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1987.tb05696.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Subsolidus compatibilities in the YO1.5‐BaO‐CuO system involving the superconducting 1:2:3 compound have been determined via optical microscopy, X‐ray diffraction, and diamagnetic susceptibility measurements. The susceptibility is particularly sensitive to the presence or absence of the superconducting

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1987.tb05697.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY