ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1961.tb13720.x

出版商:Blackwell Publishing Ltd    

年代:1961

数据来源: WILEY

摘要:

By the use of a mixture of alkali cations, Li, Na, and K, it has been possible to prepare phosphate glasses with higher M2O/P2O5, ratio than was possible by the use of a single alkali cation. Variation of the Na:K ratio over a wide range has no effect on the distribution of polyphosphates in the composition range studied (Li: Na: K = 1:5:1 to 1:1:5). Glasses with × values of 2 or less contain an appreciable amount of orthophosphate ion. The significance of these results is discussed

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1961.tb13721.x

出版商:Blackwell Publishing Ltd    

年代:1961

数据来源: WILEY

摘要:

Because of the practical importance in connection with the loss of fluorine from slags and enamels, the stabilities of NaF, KF, MgF2, CaF2, and ZnF2in dry and moist atmospheres at elevated temperatures were studied by following the loss in weight of 0.25‐ to 2.0‐gm. samples. The principal reaction was shown to be hydrolysis of the salts in moist atmospheres. The activation energies for the hydrolysis were calculated. NaF and KF were hydrolyzed little or not at all below 1000°C., MgF2was hydrolyzed readily in the range 1050° to 1150°C., CaF2was hydrolyzed slowly in the range 1200° to 1350°C., and ZnF2was completely hydrolyzed in the range 680°

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1961.tb13722.x

出版商:Blackwell Publishing Ltd    

年代:1961

数据来源: WILEY

摘要:

The 1200°C. isotherm in the system Fe‐Ti‐O has been studied by equilibrating mixtures of iron oxide (Fe2O3) and titanium oxide (TiO2) with atmospheres of controlled oxygen partial pressure. These atmospheresmnsisted of CO2, air, oxygen, mixtures of CO2and H2, and mixtures of CO2and CO. The resulting oxide mixtures were examined at room temperature by chemical analysis and by X‐ray diffraction. The stability regions of the α‐oxides (FemTi2‐mO3), of the spinels, (FenTi3‐nO4), and of the orthorhombic oxides (FepTi3‐pO5)were determined. Some nonstoichiometry occurs in the spinels and in the α‐oxides. The oxygen partial pressures at which spinel is reduced to (iron +α‐oxides) and at which α‐oxide (ilmenite) is reduced to (iron + orthorhombic oxide) were determined as 2.1 × 10−13and 9.3 × 10−14atm., respectively. The orthorhombic solid solution series extends over the whole range of ox

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1961.tb13723.x

出版商:Blackwell Publishing Ltd    

年代:1961

数据来源: WILEY

摘要:

Inert marker experiments have shown that the solid‐state reactions forming MgAl2O4and MgFe2O4occur by counterdiffusion of the Mg2+, Fe3+, and A13+ions through the relatively rigid oxygen lattice of the spinel or ferrite. It is suggested that earlier claims that ZnAl2O4forms by diffusion of Zn2+and O2‐ions were probably due to a splitting of the markers, leaving some marker on the specimen surface. Pores in one component of a reacting couple are shown to serve as inert markers. The formation of those materials, e.g., ferrites and stannates, which dissolve marker materials can now be stud

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1961.tb13724.x

出版商:Blackwell Publishing Ltd    

年代:1961

数据来源: WILEY

摘要:

Additions of NiO, CoO, MnO2, Fe2O3, and CuO promote the anatase‐rutile transformation and grain growth of TiO2. Additions of Na2O and WO3retard the transformation and have no effect on the grain growth. The addition of MoO3strongly promotes the grain growth but has only a slight effect on the phase transformation. Both the grain growth and transformation are promoted slightly by Cr2O3. The transformation is significantly affected by the method of preparing TiO2. The grain size of TiO2heated in H2exceeds that of TiO2heated in O2, in air, in argon, and in vacuum. The rate of transformation decreases with an increase in the partial pressure of oxygen of the atmospher

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1961.tb13725.x

出版商:Blackwell Publishing Ltd    

年代:1961

数据来源: WILEY

摘要:

The high‐temperature formation of zircon from zirconium dioxide and silicon dioxide in the presence of vanadium pentoxide was studied. A reaction between zirconium dioxide and vanadium pentoxide appeared to take place at about 730°C. That reaction product then reacted with silicon dioxide to form zircon. The experiments suggest that such zircon contains a few per cent of tetravalent vanadium in solid solution and has a light blue color. It appeared that the end product under equilibrium conditions would be pure zirconium silicate since vanadium pentoxide or tetroxide was liberated under prolonged heating. Zircon also formed from silicon dioxide and zirconium dioxide in the presence of niobium or tantalum pentoxi

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1961.tb13726.x

出版商:Blackwell Publishing Ltd    

年代:1961

数据来源: WILEY

摘要:

Fe or Fe + Fe2O3was heated in a stream of carefully dried oxygen, and the amount of water carried by the gas was determined as a function of time and temperature in the range 300° to 1100°C. Water was evolved as a result of a reaction with the crucible. This water was absorbed by FeO when FeO was present, and was released when the FeO was converted to Fe3O4. The apparent excess of O or deficit of Fe in FeO, reported in the literature, therefore may be due to the presence of water or hydroxide in the FeO. The other oxides, which occur in the phase diagram with exact stoichiometry, absorbed and held much less water, if an

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1961.tb13727.x

出版商:Blackwell Publishing Ltd    

年代:1961

数据来源: WILEY

摘要:

Solid solutions based on sodium niobate with limited amounts of lead and zirconium or lead and titanium solute ions have been investigated with respect to their dielectric constant versus temperature at 1 kc. per second from −175° to 300°C. Lead zirconate additions to sodium niobate up to 15 mole % cause an increase in dielectric constant, with a value of 1345 at 6°C. being the maximum recorded. Lead titanate additions to sodium niobate cause a general increase in dielectric constant up to 25 mole %, with 675 at 30°C. and 4670 at 154°C. being the maximum values recorded. Polarization versus applied field measurements up to 30,000 volts per cm. show nonreversible polarity for the lead zirconate compositions, whereas the compositions containing from 10 to 50 mole lead titanate are ferroelectric. An induced ferroelectricity phenomenon occurs for the composition containing 5 mole % lead titanate. A remanent polarization of 15 microcoulombs per sq. cm. at a coercive force of 7800 volts per cm. was obtained at room temperature for the composition 0.85 NaNbO3–0.1

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1961.tb13728.x

出版商:Blackwell Publishing Ltd    

年代:1961

数据来源: WILEY

摘要:

Crystals of yttrium iron garnet grown from lead oxide and lead oxide‐lead fluoride flux systems are inhomogeneous and contain characteristic imperfections that may be significant in the evaluation of physical properties. A petrographic study of single‐crystal sections has revealed dendritic nuclei, oriented layers of submicroscopic foreign material located in the outer regions of the crystals, and oriented occlusions in intermediate positions. Changes in the appearance of thin sections resulting from the use of an oxygen atmosphere during synthesis combined with other observations indicate that divalent iron contributes to inhomogeneities and imperfections present in yttrium iron garnet crystals. Growth mechanisms involving an initial dendritic stage with (100) and (111) fast‐growth directions followed by layered growth parallel to major crystal planes, normally (110) and (211), can be deduced from the appearance and location of crystal imperfec

ISSN:0002-7820    

DOI:10.1111/j.1151-2916.1961.tb13729.x

出版商:Blackwell Publishing Ltd    

年代:1961

数据来源: WILEY