ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1964.tb13830.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

With the discovery of techniques for controlling the nucleation and crystallization of many glass compositions came the need for improved methods for determining the percent crystallinity of a variety of glass‐ceramic materials where the crystal size was generally too small for analysis with the polarizing microscope. The development of areal analysis, lineal analysis, and point‐counting methods is reviewed. The application of the point‐counting method employing electron microscopy and diffraction to glass‐ceramic materials is discussed and demon

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1964.tb13831.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

A new technique has been developed by which thin sections of glass‐ceramics can be prepared for direct observation by transmission electron microscopy. Techniques for identifying crystalline phases are discussed, and the degree of crystallinity in several glass‐ceramics is presen

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1964.tb13832.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

A method of making dielectric measurementsin situunder pressures up to 60 kbars is described. This technique has been used to investigate the effect of very high pressure on the activation energy for conduction in an aluminosilicate glass system. The activation energy increased rapidly at first with pressure and then exhibited saturation at pressures above 30 kbars. This investigation also showed a remanent increase in the activation energy in a glass compacted at a pressure of 42.2 kbars. The results obtained are discussed in the light of current models for the charge migration in soda glass.

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1964.tb13833.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

The constitution of glasses in the system NaPO3‐LiF with the M/P ratio varying from 1.66 to 1.22 and melted in laboratory air and in dry air has been determined. It has been found that when the glasses are melted in laboratory air and quenched immediately after the components have melted into a liquid, most of the fluorine is retained by the glasses; if, however, the melts are heated further, fluorine is gradually replaced by oxygen. Weight‐loss determinations on the glasses in the solid state and on the melts agree with the foregoing conclusions. In dry air very little fluorine is lost from the melts even after 1 hour. Chromatographic and infrared analyses show that glasses retaining fluorine contain considerable amounts of monofluoro‐orthophosphate groups; only about half the fluorine is present, however, in this form. The distribution of the remaining fluorine is not

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1964.tb13834.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

Soda‐lime glass rods 5 mm in diameter were quenched in silicone oil and also in a saturated hydrocarbon oil of similar viscosity. The effect of etching, etching and quenching, and etching, quenching, and re‐etching was examined in relation to the strength of the rods. Rods quenched in the silicone oil were no stronger than those quenched in the hydrocarbon oil. Etched rods had a strength of 300,000 psi. Quenching these high‐strength rods reduced their strength to 110,000 psi. This decrease in strength may be explained in terms of the formation of crystalline and noncrystalline microflaws during the heating and cooling cycle. Re‐etching, after quenching, resulted in rods with a maximum strength of 384,

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1964.tb13835.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

The thermal decomposition of europium hydroxide in an air atmosphere was investigated by means of weight‐loss measurements, infrared spectroscopy, X‐ray diffraction analysis, and electron microscopy. These studies showed that EU(OH)° decomposed at temperatures between 225° and 300°C into EuOOH, which was stable up to about 425°C. Between 435° and 465°C this compound decomposed into cubic Eu2O3, which was stable until its inversion to the high‐temperature monoclinic form. X‐ray diffraction data were collected for Eu(OH)3and EuOOH and showed that the trihydroxide has a hexagonal crystal structure and the oxyhydroxide is possibly orthorhombic. The Eu(OH)2, EuOOH, and cubic EunOa powders contained particles up to several microns in size consisting of agglomerates of crystallites in the size range 200 to 400 A. The single monoclinic Eu2O3sample studied contained crystallites whose average size was greate

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1964.tb13836.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

The solubility of ZnAl2O4(gahnite spinel) and NZOI (corundum) in their respective molten PbF2solutions was determined by a sealed‐tube quenching method between 900° and 1250°C. Differential thermal analysis was used below 900°C. The solubilities (crystal‐constituent/ PbF2weight ratio) at 1200°C were 0.151 for A12O3and 0.108 for ZnAl2O4, whereas at 900°C they were 0.093 and 0.048, respectively. These results are compared with those of single‐crystal growth experiments and the crystalline products are

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1964.tb13837.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

The release of xenon from lightly irradiated uranium monocarbide powders was studied in the temperature range 150° to 975°C. Release in this range is much higher than that calculated by extrapolating high‐temperature diffusion data. The kinetics of the release agree with a model in which the xenon in the first three or four unit cells is released over a range of activation energ

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1964.tb13838.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY

摘要:

The effects of composition, post sintering, and operating temperature in a square‐loop ferrite system of interest for performing logic functions in digital telemetry applications are described. Ceramic processing methods used in preparing the multiaperture ferrite cores for this study are also described. Magnetic hysteresis loop characteristics of squareness ratio (Ra), magnetic induction switched (δBm), critical switching field (Hc, and maximum permeability (μm,) are reported as a function of zinc concentration in the system Mg0.5‐tMn0.8ZnxFe1.7O4abc. These characteristics are also investigated as a function of the post‐sintering treatments of air quenching and nitrogen annealing for the composition Mgo.35Zn0.15Isel Essentially identical results are obtained for both the air‐quenching and the nitrogen‐annealing treatments. Significant hysteresis loop characteristics are shown at various operating temperatures in the range −7

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1964.tb13839.x

出版商:Blackwell Publishing Ltd    

年代:1964

数据来源: WILEY