ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1961.tb15348.x

出版商:Blackwell Publishing Ltd    

年代:1961

数据来源: WILEY

摘要:

In semiconductor fabrication it is common practice to use a grain‐growth promoter with pure germanium or silicon with very small quantities (parts per million) of a promoting agent (such as boron or phosphorus) to obtain the desired semiconducting properties. Several materials such as antimony, boron, lead, lithium, potassium, and sodium were investigated as possible agents for the promotion of grain growth in cadmium manganese ferrites. It was noted that the characteristics of ferrites could be affected by treating with these agents before sintering. The boron additions to these ferrites accelerated the reaction rates (catalytic action) and affected the characteristics during sintering. The methods of preparation and the observed results are discusse

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1961.tb15349.x

出版商:Blackwell Publishing Ltd    

年代:1961

数据来源: WILEY

摘要:

The anomalous resistivity‐temperature characteristics found in semiconducting barium titanates were studied in relation to their composition. The resistivity and impedance characteristics and the crystal structures were investigated for different compositions in the systems (Ba, ‐Sr) (Ti, Sn)O3, (Ba, Ca, Sr)TiO3) (Ba, Pb)TiO3, Ba‐(Ti, Zr)O3, and Ba(Ti, Si)O3doped with 0.1 mole % of Ce and also in the system (Ba, Mg, Ce) TiO3. Bodies whose compositions were quite different from BaTiO3could not be semiconducting. The resistivity anomaly in each semiconducting body showed a good correlation with the crystal trans

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1961.tb15350.x

出版商:Blackwell Publishing Ltd    

年代:1961

数据来源: WILEY

摘要:

Analytical‐grade magnesium oxide powder without binder was compressed hydrostatically to 50,000 lb. per sq. in. to form compacts. When exposed to moist air immediately after pressing, these compacts developed irregularly shaped cracks. Controlled tests, in which these compacts were exposed for various lengths of time to various atmospheres, indicated that in general water vapor, carbon dioxide, and residual stresses had to be present if cracking was to occur. The probable cause of the cracking was the formation of a less dense and mechanically weak basic carbonate of magnesium at crystallite surface points of high stress concentration which developed during the compacting. The adsorption of dry CO2at such sites prevented subsequent delayed fractur

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1961.tb15351.x

出版商:Blackwell Publishing Ltd    

年代:1961

数据来源: WILEY

摘要:

Glass fibers as commercially produced have physical and mechanical properties which differ from those of the massive form of the same glass. When these fibers are subjected to subsequent heat‐treatments, the values of the measured properties tend to return to those of the massive glass. This phenomenon is called compaction because in the process density increases. The effect of compaction on the physical properties of fibers is discussed and the mechanism of this phenomenon is described briefl

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1961.tb15352.x

出版商:Blackwell Publishing Ltd    

年代:1961

数据来源: WILEY

摘要:

The energy relations existing between the congruently melting compounds Li2O ‐2B2O3, Na2O–2B2O3, Na2O‐4B2O3, and K2O‐4B2O3and their glasses have been determined for the temperature range 25° to 1100°C. High‐temperature heat‐content, entropy, and heat of solution data are given for both the glasses and the corresponding devitrified materials. A comparison of the heats of fusion of the alkali borates on a gram atom of oxygen basis shows that they follow the order Li>Na>K. The entropy differences between the glass and the corresponding crystalline material have been determined at 25°C. The free‐energy change at 25°C. for the reaction crystal → glass has been calculated for

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1961.tb15353.x

出版商:Blackwell Publishing Ltd    

年代:1961

数据来源: WILEY

摘要:

Crystalline B2O3was readily obtained from the glassy phase at high pressures and temperatures. Single crystals 0.3 mm. in dimension of both α‐B2O2(ordinary hexagonal) andβ‐B2O3(dense monoclinic) were prepared. The difference in the density of the two forms was about 20%. Crystals ofβ‐B2O3were only slowly attacked by H2O and dilute HF. At atmospheric pressure, transitions between theα‐,β‐, and liquid phases were extremely sluggish. A tentative phase diagram was constructed up to 1100°C. and 90,000 atmospheres, the probable melting curve being calculated by the use of the Simon m

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1961.tb15354.x

出版商:Blackwell Publishing Ltd    

年代:1961

数据来源: WILEY

摘要:

The conditions under which tridymite becomes a stable phase have been reinvestigated. When quartz was heated with 2% alkali oxide, tridymite formed directly at 872° to 898°C. with Na2O, at 883° to 902°C. with K2O, and above 1005°C. with Li2O. Cristobalite occurred as an intermediate phase above 893°C. with Li2O, above 898°C. with Na2O, and above 902°C. with K2O. When quartz plus sodium chloride was heated in vacuum, tridymite did not form but cristobalite started to appear at 1050°C. The results showed that the formation of tridymite can be strictly a solid‐state process. New schematic tentative diagrams for the high‐silica region of binary systems are suggested. Quartz and cristobalite are regarded as the only stable crystalline phases of pure silica. Tridymite is pictured as a binary incongruently m

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1961.tb15355.x

出版商:Blackwell Publishing Ltd    

年代:1961

数据来源: WILEY

摘要:

The phase equilibrium diagram for the system La2O3‐B2O3has been determined experimentally. The compounds La2O3‐3B2O3and La2O3‐B2O3melt congruently at 1141°± 5°C. and 1660°± 15°C, respectively. At 1488°± 5°C, La2O3‐B2O3inverts from the aragonite‐type structure to a high‐temperature form. Trilanthanum borate, 3La2O3B2O3, melts incongruently at 1386°± 5°C. to give liquid and La2O3. No solid solutions exist in the system. A region of liquid immiscibility exists in the system and extends at 1136°± 5°C. from almost pure B2O3to 21.5 mole % La2O3. The experimental value for the extent of immiscibility agrees with that calculated from theoretical considerations. A second method for estimating immiscibility in the system is demonstrated, which requires experimentally only the determination of the index of refraction of the modifier‐rich liquid. Principles governing

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1961.tb15356.x

出版商:Blackwell Publishing Ltd    

年代:1961

数据来源: WILEY

摘要:

Subsolidus phase relations in the binary system PbO‐Ta2O5were investigated by the quenching method. The following compounds were identified by X‐ray diffraction patterns: PbO ‐2Ta2O5, PbO Ta2O6, 3PbO 2Ta2P5, 2PbO Ta2O6, 5PbO ‐2Ta2O5, and 3PbOTa2O5The 1:1 compound has rhombohedral symmetry when it is prepared below 1150°C. Above this temperature, it yields an orthorhombic phase. Compounds with the same ratio of lead oxide to pentoxide exist in the systems PbO‐Ta2O6and

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1961.tb15357.x

出版商:Blackwell Publishing Ltd    

年代:1961

数据来源: WILEY