Showing papers on "Solid solution published in 1970"

Experimental measurement of hydrate numbers for methane and ethane and comparison with theoretical values

Abstract: Methane and ethane hydrate number measurement, alleviating liquid water occlusion and evaluating pressure effect

Liquid‐Phase Epitaxy of In × GA 1 − × As

Abstract: layers grown by liquid‐phase epitaxy were obtained in the range of , when grown on the (111 Ga) plane of GaAs. Attempts to grow alloys on the (110), (111 As), (100), and (112 As) planes resulted in polycrystalline layers. The alloy composition was determined by x‐ray fluorescence and the band gap by infrared transmission. The ternary‐phase diagram was calculated using Darken's quadratic formalism to describe the ternary liquid and assuming the solid solution in equilibrium with the liquid to be regular. It was found that the experimental results were in good agreement with the calculated phase diagrams. A number of liquidus isotherms were calculated in the temperature range of 700°–1200°C. Gallium arsenide isoconcentration curves are shown for 0.95, 0.90, 0.80, 0.50, and 0.30 mole fraction.

Phase Equilibria Relations in the Ternary System BaO ‐ SrO ‐ Nb2 O 5

Abstract: Phase equilibria in the binary system and the ‐rich region of the ternary system were investigated by DTA, x‐ray diffraction, strip heater, and Curie temperature measurement techniques. The ternary‐phase fields of three tetragonal‐tungsten‐bronze type structures have been located, Only one of these structures is a ternary compound; it is located along the binary join, extending from 20 to 80 m/o , and melts congruently near 50% . The ternary solubility extends from about 4% excess to about 1% excess . This phase possesses observable orthorhombic distortion in the ‐rich region of the solid solution. The implications of the phase diagram for the crystal growth of these compounds are briefly discussed.

Pentlandite phase relations in the Fe–Ni–S system and notes on the monosulfide solid solution

Abstract: A curve relating composition of synthetic pentlandite with interplanar spacing was determined experimentally as follows: d115 = 1.9407 – 0.0023x + 0.0077x2, where x represents the iron to nickel we...

Factors influencing the formation of silver-rich solid solutions in rare- earth--silver alloy systems.

Abstract: The solid solubilities of all of the naturally occurring rare-earth metals in silver have been determined by using the X-ray parametric method. The solubilities range from 0.01 to 0.02 at. pct for Eu to 10.5 at. pct for Sc. The stoichiometries of the silver-rich compounds and some of their crystal structures were determined. The silver-rich compounds found in this study are: RAg5(La, Ce, Pr, Eu, and Yb), RAg4(Lu and Sc), R14Ag5l(La to Sm, Gd to Er, Yb, and Y) and TmAg3. The silver/silver-rich compound eutectic temperatures were also determined. Analysis of these data indicates that several factors in addition to the Hume-Rothery criteria influence the formation and extent of solid solutions. These include the mutual adjustment of size and electronegativity of the solvent and solute if the pure metal size differences are less than a critical value of 22 to 25 pct, the composition of the first solvent-rich compound, and the lattice rigidity of the solvent.

Solvent self-diffusion in dilute b.c.c. solid solutions

Abstract: This paper completes and extends the calculations previously made (Le Claire 1970 a) of the influence of small concentrations of solute on the solvent self-diffusion rate in dilute b.c.c. substitutional solid solutions. Proper account is now taken of correlation effects in the solvent diffusion: mean partial correlation factors are calculated and tabulated as functions of the appropriate atom jump frequency ratios. The calculations are performed for two dilute solution models, differing in the assumptions made about the effects of the solute on the solvent jump frequencies and on the extent of vacancy-solute binding. One model, assuming binding at both 1st and 2nd neighbour distances, is the same as was discussed in the previous paper. The second model assumes vacancy-solute binding at the 1st neighbour separation only and that all dissociative vacancy jumps from nearest-neighbour sites of a solute atom occur at the same frequency. The results of the calculations, for both models, are used to dis...

The Preparation and Crystallography of Cadium Zinc Sulfide Solid Solutions

Abstract: Single crystals and powders of were grown using chemical transport with iodine. These components form a continuous series of solutions over the entire range of x, 0 to 1. The wurtzite structure was produced over the entire range. The lattice parameters and the composition of the solid solutions were determined to approximately 1% using x‐ray diffractometry techniques. The results provide a definitive calibration of lattice constants for the wurtzite structure of solid solutions of and and allow the analysis of samples. The variation of lattice parameters with composition was found to obey Vegard's law. The variation of the c/a ratio with composition was also linear. The ideal ratio, assuming close packing of hard spheres, occurred at 70% . The volume relationship with composition showed a slightly negative deviation from linearity. A least squares method for refining lattice parameters is described.

The solution hardening of β-rhombohedral boron

Abstract: Solid solutions of transition metals in β-rhombohedral boron have been investigated using X-ray techniques and microhardness measurements. The variation of microhardness with unit cell volume is discussed.

Activities and phase boundaries in the Cr-Ni system using a solid electrolyte technique

Abstract: The solvus lines in the Cr-Ni phase diagram have been determined with a solid electrolyte technique. Also, the solidus and liquidus lines have been calculated by thermodynamic methods and these are compatible with the solid solution phase boundaries which were determined by experiment. Some features of this study correlate quite well with previous investigations. The resultant diagram substantiates the one proposed by Hansen. The solvus lines have been more accurately positioned by these experiments.

Lattice parameters, thermal expansion coefficients and densities of Nb, and of solid solutions Nb–O and Nb–N–O and their defect structure

Abstract: The temperature expansivities (by the X-ray method), the densities and the defect structures of the 3 cubic nonstoichiometric compounds (solid solutions) of the composition Nb, NbO0.017 and NbN0.90O0.013 (nitride) were determined. The lattice parameters a at 25°C were: 3.3004, 3.3047 and 4.3855 A; the linear expansion coefficients, α, between 15 and 65°C were 7.6, 8–65 and 7–75 × 10–6°C−1 respectively. As the temperature is increased, α undergoes several changes in magnitude. The cubic nitride started to decompose at about 850°, with a loss of N (decrease of α). The structure of the oxygen-poor Nb is free from vacancies and interstitial atoms within the limits of error; that of the oxygen-rich Nb contains interstitial atoms on additional sites in a concentration of 1.9%, and the nitride contains vacant sites in both sublattices (4.8% total).

Thermodynamics of the Iron‐Nickel‐Oxygen System at 1000°C

Abstract: : The isothermal section of the Fe-Ni-O system at 1000 C has been defined by determining the compositions and structures of the equilibrated solid phases Wustite can coexist with Fe-Ni alloys containing up to 796 a/o (atomic percent) Ni The three-phase field wustite-spinel-alloy consists of wustite containing 051 a/o Ni, spinel containing 06 a/o Ni, and an alloy containing 796 a/o Ni The three-phase field, spinel-nickel oxide-alloy, consists of nickel ferrite, nickel oxide containing 65 a/o Fe, and an alloy containing 995 a/o Ni Tie lines in the spinel-alloy field were investigated in detail Wustite-nickel oxide solid solutions exhibited nonideal behavior (Author)

Separation of Phases by Spinodal Decomposition in the Systems Al2O3−Cr2O3 and Al2O3−Cr2O3−Fe2O3

Abstract: Separation of phases was investigated in the hexagonal (rhombohedral) systems Al2O3−Cr2O3 and Al2O3−Cr2O3−Fe2O3. The binary system shows a miscibility gap with a Tc of 950°C; the miscibility gap for the ternary system was determined for a constant Cr2O3 content of 16.6 mol%. Dark field transmission electron microscopy of solid solutions annealed within the miscibility gap showed dark and light lamellas ∼50 to 200 A thick. X-ray diffraction results for the solid solutions in the ternary system indicated that, in the early stages of annealing, broadening occurred only on (hkl) reflections where l≠0. There was no major change in the X-ray diffraction patterns of the annealed solid solutions in the binary system. Electron diffraction results indicated, however, that phase separation in both systems proceeded in the [001] direction. Solid solutions in the binary system separated very slowly; the separation could be enhanced hydrothermally. The mechanism of the separation of phases in both systems is spinodal and proceeds as follows: solid solution→intermediate modulated phase→equilibrium phases.

Dielectric and Piezoelectric Properties of Pb(Co1/3Nb2/3)O3‐PbTiO3‐PbZrO3 Solid Solution Ceramics

Abstract: Ceramic and piezoelectric properties of the Pb(Co1/3Nb2/3)O3-PbTiO3-PbZrO3 system were investigated The system contains rhombohedral, tetragonal, and pseudocubic phases at room temperature The triple point is at 007Pb(Co1/3Nb2/3)O3-043PbTiO3-050PbZrO3 High dielectric constants (750 to 1500) and radial coupling coefficients (40 to 45%) and low average temperature coefficients of resonant frequency (of the order of 10-6°C) were obtained for compositions near the morphotropic phase boundary

Interstitial Order-Disorder Transformation in the Ti-O Solid Solution. IV. : A Neutron Diffraction Study

Abstract: Interstitial order-disorder transformation regarding oxygen atoms dissolved in alpha-titanium has been studied by neutron diffraction on single crystals in the range from 17 to 28 at% O. Occupation probabilities of the oxygen atoms in the octahedral interstitial sites are determined quantitatively with the variation of composition and temperature. The change of the long-range order with increasing temperature reveals a two-step process attributed to the disordering of the oxygen atoms. The static displacement of the titanium atoms parallel to the c -axis increases almost linearly with the oxygen concentration. The results are compared with the previous works in Parts I, II and III.

The optical properties of Sb2Se3Sb2Te3

Abstract: The optical properties of single crystal specimens of Sb2Te3Sb2Se3 solid solutions have been investigated in the photon energy range 0.04 eV to 6.5 eV. A wide range of solid solutions having hexagonal structure were found to exhibit properties closely corresponding to the isostructural compounds Bi2Te3 and Bi2Se3. Small indirect band gaps approaching semimetallic values were obtained. The high free-carrier concentrations gave rise to plasma effects in the near infra-red. In contrast Sb2Se3 is orthorhombic with a direct band gap near 1 eV. The chemical bonding concepts applied to similar systems seem applicable with only slight modification.

Interstitial Order-Disorder Transformation in the Ti-O Solid Solution. IV. A Neutron Diffraction Study

Abstract: Interstitial order-disorder transformation regarding oxygen atoms dissolved in alpha-titanium has been studied by neutron diffraction on single crystals in the range from 17 to 28 at% O. Occupation probabilities of the oxygen atoms in the octahedral interstitial sites are determined quantitatively with the variation of composition and temperature. The change of the long-range order with increasing temperature reveals a two-step process attributed to the disordering of the oxygen atoms. The static displacement of the titanium atoms parallel to the c -axis increases almost linearly with the oxygen concentration. The results are compared with the previous works in Parts I, II and III.

Phase Equilibria in the KNbO3‐SrNb2O6 and KNbO3‐BaNb2O6 Systems

Abstract: Phase equilibrium studies of the KnbO2-SrNb2O6 system revealed that tetragonal tungsten bronze-type solid solutions extend from 59 to 87 mol% SrNb2O6. The solid solution field has a relatively flat liquidus peaking at 1486°C and 78 mol% SrNb2O6. In contrast, solid solutions are limited to 67 to 75 mol% BaNb2O6 in the KnbO3-BaNb2O6 system, with peritectic decomposition occurring at the 75 mol% solid-solution limit. The diagrams establish conditions for perfecting the growth and stoichiometry of potassium-strontium and potassium-barium niobate electrooptic crystals. Dielectric and crystallographic properties of crystals grown in these systems are presented, and the phase relations are compared to previous work in the sodium-barium niobate system.