ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1971.tb12304.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

Glass fibers and rods with radially parabolic refractive‐index distributions were produced by exchanging potassium ions from a salt bath or a lower‐index cladding glass for thallium ions in the glass composition. A fiber 1 m long and 0.25 mm in diameter could be bent around a curve of radius 10 cm without deforming the Gaussian mode pattern; the depolarization of a laser beam was<−20 dB. The resolution of a rod 3.14 mm long and 1.0 mm in diameter with a focal length of 1.64 mm was of the order of 450 lines/mm. Attenuation (caused primarily by absorption induced by trace impurities) was 100 to 250 dB/km at 6328 Å; since further improvement with respect to loss is expected, these fiber guides are promising materials for use in long‐distance optical commun

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1971.tb12305.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

The sintering of uranium mononitride (UN) depends on temperature and the N2pressure maintained over the nitride during heat treatment. At a given temperature, an N2pressure that maintained the UN in the single‐phase region slightly above the phase boundary where the reaction UN→U+½N2(g) occurred was most effective in accelerating the sintering of single‐phase UN. For example, specimens sintered at 1600°C under N2pressures of either 1140 or 1.7XlO−4torr had essentially identical compositions, but the density of the former was 10.78 g/cm3(75% of theoretical), whereas that of the latter was 12.20 g/cm3(85% of theoretical). Results were similar at temperatures up to 2100°C. The X‐ray lattice constant of UN sintered at reduced N2pressures was slightly larger than that of UN sintered in 1140 torr of N2. The observed constants ranged from 4.88904 to 4.88991 Å; the combined O+C content varied from 4

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1971.tb12306.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

A linear relation is established between the cosine of the contact angle and the temperature of a liquid metal sessile drop resting on a ceramic substrate. This relation is demonstrated for many liquid metal/ceramic systems. The work of adhesion and the effects of surface roughness, porosity, chemical reactions, and structural transformations in the substrate surface are also discussed.

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1971.tb12307.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

The solid‐state reaction between MnxO and MgO was studied at 1380°, 1480°, and 1565°C in air and at 1500°C at Po2= 10−9atm. Diffusion occurs by counterdiffusion of Mg and Mn ions through a rigid oxygen lattice. A Kirkendall effect (not marker‐detectable) is described in which the Mg flux equals the Mn plus vacancy flux. The system activation energy for diffusion was ∼2 eV (41 kcal/mol). An extension of Darken's treatment was used to interpr

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1971.tb12308.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

Samples of 65 μm‐grain‐size AL2O3containing 0.05 wt% Mg and 40 μm‐grain‐size AL2O3containing 0.13 wt% Mg, both MgO‐saturated, undergo compressive deformation in the range 1580° to 1800°C with results interpreted as diffusional creep rate‐limited by grain‐boundary diffusion with the Coble boundary‐diffusion model givingA lower deformation rate for an unsaturated composition indicates that MgO additions enhance grain

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1971.tb12309.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

Four compounds analogous to the humite minerals were synthesized in the system Mg2GeO4‐MgF2by crystallization from melts and solid state reaction techniques. Precise optical and X‐ray diffraction data were obtained. Several other phases were observed within the system MgO‐GeO2

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1971.tb12310.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

A technique for growing α‐Al2O3crystals is described in which Na2O·11Al2O3is dissolved in a liquid of composition Na2O·4TiO2·3Al2O3. Alpha Al2O3is precipitated as Na2O evaporates from the system; Na2O·11Al2O3serves as a source of Al2O3, and Na2O in the liquid. The content of solids in the mixture is always such that it does not melt completely. The size of the α‐Al2O3crystals grown is related to the Na2O content of the composition. Crystals as large as 4000 by 3000 μm in the α‐axis direction and 500 μm in thec‐axis direction

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1971.tb12311.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

Interdiffusion coefficients in single‐crystal MgO were determined using an MgO‐MgAl2O4diffusion couple. For a concentration of 1 mol% Al2O3in MgO, the interdiffusion coefficient can be expressed asD=2.0±0.2 exp (−76,000±3,000/RT) for the MgO‐MgAl2O4couple. This relation compares well with previous measurements in the MgO‐Al2O3system. The interdiffusion coefficients, which increased with the mol fraction of cation vacancies, were in the range of 10−8to 10−10cm2s−1for the concentrations and temperatures studied. Diffusion was enhanced below 1640°C if powdered MgAl2O4was used. Self‐diffusion coefficients for Al3+ions in MgO were calculated; Al3+diffuses fa

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1971.tb12312.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1971.tb12313.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY