Composition Dependence Of Lattice Parameters Research Articles

Energetics and structure of the B‐type solid solution in the Nd2O3–Y2O3 system

AbstractThe system Nd2O3–Y2O3 contains solid‐solution phases with several different structures. Single‐phase B‐type (Nd1−xYx)2O3 solid solutions in the range of were formed at 1873 K and retained on cooling to ambient temperature. They showed a linear composition dependence of lattice parameters, enabling extrapolation to x = 0 and 1 for comparison with the structures of the stable endmembers. A positive enthalpy of formation from A‐type Nd2O3 and C‐type Y2O3 determined using oxide melt solution calorimetry indicated entropic stabilization of the B‐type phase. A positive interaction parameter for mixing in the B‐type solid solution, Ω 47.46 ± 4.04 kJ/mol, was obtained by fitting the data using a regular solution model. This value is significantly more positive than that obtained by previous phase diagram analysis using the CalPhaD approach. Exsolution into two B‐type phases is predicted to occur below 1427 K, making it unimportant for the equilibrium phase relations that will be dominated by other structures at low temperature.

Phase equilibria in the Tl5Te3–Tl9BiTe6–Tl9TbTe6 system

Phase equilibria in the Tl5Te3–Tl9BiTe6–Tl9TbTe6 system have been studied using differential thermal analysis, X-ray diffraction, and microhardness measurements. We have mapped out a number of vertical sections, the 760-K isothermal section of its phase diagram, and projections of its liquidus and solidus surfaces. The composition dependences of lattice parameters and microhardness have been obtained. The system has been shown to contain a continuous series of solid solutions, which crystallize in a tetragonal structure (Tl5Te3 type, sp. gr. I4/mcm).

Composition dependence of lattice parameters and band gap energies of thallium based layered mixed crystals

Compositional dependence of lattice parameters and unit cell volumes of TlMeX2-type (Me = Ga or In and X = S or Se) layered mixed crystals with monoclinic structure has been studied by X-ray diffraction technique. It is revealed that the lattice parameters of TlGa1−xInxSe2, TlGa(S1−xSex)2, TlGa1−xInxS2 and TlIn(Se1−xSx)2 mixed crystals increase due to the substitution of gallium atoms by indium and sulfur atoms by selenium. Moreover, the absorption edges of these mixed crystals have been investigated through the transmission and reflection measurements in the wavelength range of 400–1,100 nm. The analysis of absorption data has revealed the presence of both optical indirect and direct transitions. It is found that the energy band gaps of mixed crystals decrease due to the substitution of gallium atoms by indium and of sulfur atoms by selenium.

Structure, magnetism, and magnetic compensation behavior of Co50-xMn25Ga25+x and Co50-xMn25+xGa25 Heusler alloys

The structure, magnetism, magnetic compensation behavior, exchange interaction, and electronic structures of Co50-xMn25Ga25+x and Co50-xMn25+xGa25 (x = 0–25) alloys have been systematically investigated by both experiments and first-principles calculations. We found that all the samples exhibited body centered cubic structures with high degree of atomic ordering. With increasing Ga content, the composition dependence of lattice parameter shows a kink point at the middle composition in Co50-xMn25Ga25+x alloys, which can be attributed to the enhanced covalent hybridization between the main-group Ga and the transition-metal atoms. Moreover, a complicated magnetic competition has been revealed in Co50-xMn25Ga25+x alloys, which causes the Curie temperature dramatically decrease and results in a magnetic moment compensation behavior. In Co50-xMn25+xGa25 alloys, however, with increasing Mn content, an additional ferrimagnetic configuration is established in the native ferromagnetic matrix, which causes the molecular moment monotonously decrease and the exchange interaction enhance gradually. The electronic structure calculations indicate that the Co50-xMn25+xGa25 alloys are likely to be in a coexistence state of the itinerant and localized magnetism. Our study will be helpful to understand the nature of magnetic ordering as well as to tune magnetic compensation and electronic properties of Heusler alloys.

Structural, Dielectric and Complex Impedance Spectroscopy Studies of Lead Free Ca0.5+xNd0.5−x(Ti0.5Fe0.5)O3

Structural and various electrical properties of polycrystalline Ca 0.5+ x Nd 0.5− x (Ti 0.5 Fe 0.5 )O 3 , prepared by standard solid state reaction technique, were studied. Formation of single phase orthorhombic structure of the compositions was confirmed by X-ray diffraction study. The composition dependence of lattice parameters, density and microstructural study show that they vary significantly with Ca content. The dielectric measurements were carried out at room temperature as function of frequency and composition. The experimental results reveal that the dielectric constant ( e ′) increases with increasing Ca content. Similar behavior is observed for the dielectric loss (tan δ ) and ac conductivity ( σ ac ). In complex impedance analysis it is observed that the real part ( Z ′) vs imaginary part ( Z ″) graph exhibits a tendency of formation of a single semicircular arc for each composition of samples. Different parameters were determined by fitting the experimental data in Cole–Cole empirical formula. A dominance of grain boundary resistance ( R gb ) is observed. The R gb decreases with increasing Ca content. The high e ′ observed in present samples are suitable for fabrication of devices.

Phase equilibria and properties of solid solutions in the Tl5Te3-Tl9BiTe6-Tl5Te2I system

Phase equilibria in the Tl5Te3-Tl9BiTe6-Tl5Te2I system, containing ternary structural analogs of Tl5Te3, have been studied by differential thermal analysis, X-ray diffraction, microhardness tests, and emf measurements using concentration cells with a thallium electrode. A number of T-x sections, the 760- and 800-K sections, and the liquidus and solidus projections of the phase diagram are constructed, and the composition dependences of lattice parameters, microhardness, and emf are obtained. The results demonstrate that, despite the presence of a liquid-liquid miscibility gap, the system contains a continuous series of solid solutions isostructural with Tl5Te3.

Phase equilibria and crystal structures of solid solutions in the system LaCoO3−δ-SrCoO2.5±δ-SrFeO3−δ-LaFeO3−δ

The composition region and structure of La1−x Sr x Co1−y Fe y O3−δ solid solutions are determined by x-ray powder diffraction using the Rietveld profile analysis method. The solid solutions based on lanthanum cobaltite, LaCoO3−δ, have a rhombohedrally distorted perovskite-like structure (sp. gr. R $$\bar 3$$ c), and those based on lanthanum ferrite, LaFeO3−δ, have an orthorhombically distorted structure (sp. gr. Pbnm). The rhombohedral distortion decreases with increasing strontium content, and the solid solutions with x ≥ 0.5 have an ideal cubic structure (sp. gr. Pm3m). The composition dependences of lattice parameters for the La1−x Sr x Co1−y Fe y O3−δ solid solutions are presented, and the 1100°C isotherm of the LaCoO3−δ-SrCoO2.5±δ-SrFeO3−δ-LaFeO3−δ system in air is constructed.

Homogeneity Range of Samarium Manganite in Air

The solubility limits of samarium and manganese oxides in SmMnO3 are determined using x-ray diffraction analysis of Sm2 − x MnxO3 samples (0.90 ≤ x ≤ 1.20, Δx = 0.02) prepared from oxide mixtures by solid-state reactions in air between 800 and 1400°C. The composition dependences of lattice parameters are presented for samarium manganite synthesized at 1400°C. The solubility of samarium oxide in SmMnO3 is tentatively attributed to structural defects, and that of manganese oxides is interpreted in terms of structural defects, oxygen nonstoichiometry of samarium manganite, the disproportionation reaction 2Mn3+ =Mn2+ + Mn4+, and partial substitution of the resulting Mn2+ for Sm3+ on the cuboctahedral site of the perovskite structure.

Phase equilibria at 1100�C in air and crystal structure of solid solutions in the system LaCoO3?SrCoO2.5??SrNiO3???LaNiO3?

Phase equilibria in the LaCoO3—SrCoO2.5—“SrNiO3”—“LaNiO3” system are studied at 1100°C in air using samples prepared by standard solid-state reactions and by the citrate route. The composition region and structure of La1 − xSr x Co1 − yNi y O3 − δ solid solutions are determined by x-ray powder diffraction. The structure is refined by the Rietveld profile analysis method with Fullprof 2002. The solid solutions with 0< x ≤0.5 have a rhombohedrally distorted perovskite structure (sp. gr.R $$ \bar 3 $$ c). The rhombohedral distortion decreases with increasing Sr content, and the solid solutions with x > 0.5 have an ideal cubic structure (sp. gr. Pm3m). The composition dependences of lattice parameters for the La1 − xSr x Co1 − yNi y O3 − δ solid solutions are presented.

Phase Equilibria and Structure of Solid Solutions in the La–Co–Fe–O System at 1100°C

Phase equilibria in the La–Co–Fe–O system are studied at 1100°C in air using samples prepared by the citrate, nitrate, and conventional ceramic routes. The stability regions and structures of solid solutions in the La–Co–Fe–O system are determined by x-ray powder diffraction: LaCo1 – y Fe y O3 – δ (0 < y ≤ 0.25, sp. gr. R $${\bar 3}$$ c; 0.775 ≤ y< 1, sp. gr. Pbnm), Co1 – y Fe y O (0 < y ≤ 0.13, NaCl-type structure, sp. gr. Fm3m), and Fe3 – x Co x O4 (0.84 ≤ x ≤ 1.38, sp. gr. Fd3m). The structural parameters of phase-pure solid solutions are determined by the Rietveld method. The composition dependences of lattice parameters are presented for LaCo1 – y Fe y O3 – δ (0 < y≤ 0.25) and Fe3 – x Co x O4 (0.84 ≤ x ≤ 1.38). The 1100°C isotherm of the pseudoternary system La2O3–CoO–Fe2O3 in air is constructed.

Phase Diagram and Luminescent Properties of CdTe–MnTe Solid Solutions

The T–x phase diagram of the CdTe–MnTe system is mapped out. The CdTe–MnTe join is shown to be nonpseudobinary. The system contains an extended series of CdTe-based solid solutions (0–71.4 mol % MnTe at 1070 K). At 1070 K, α-MnTe dissolves up to 0.3 mol % CdTe. Data are presented on the composition dependences of lattice parameters for the solid solutions studied and the luminescent properties of Cd1 – x Mn x Te single crystals annealed in cadmium or tellurium vapor.

Continuous Solid Solution of -K-phase in the Third Period Transition Metals-Aluminum-Carbon Pseudo-Ternary Systems

ABSTRACTPhase stability of κ-phases (perovskite-type phases) was studied in the third-period transitionmetals (M: Mn to Cu) - aluminum (Al) - carbon (C) systems. The concentrations of transition metals (CM) were systematically changed from 60mol%Mn to 20mol%Ni+40mol%Cu along the periodic table under the constant nominal alloy compositions of CMl+CM2=60mol%, CA1=60mol% and Cc=20mol%. Alloys were prepared using mechanical alloying and hot pressing. Constituent phases were investigated by X-ray diffraction analysis, scanning electron microscopy and electron probe microanalysis. It is confirmed that Mn3Al(C,O)0,95, Fe3Al(C,O)0.87, Co3AI(C,O)0. 6 and Ni3Al(CO)0.26 exist in their ternary systems where oxygen is introduced during the process. Also, only one κ-phase is recognized in an alloy having an intermediate composition in every system. This suggests that continuous solid solutions between these κ-phases are formed in the pseudo-ternary systems. Composition dependence of lattice parameter is discussed.

Mössbauer studies on valence change of rare-earth ions Ce 1− xR xFe 2 ( R = La, Pr, Nd)

MgCu 2-type compounds Ce 1− x R x Fe 2 ( R = La, Pr, Nd) annealed at 1000 K are single phase in x ⩽ 0.2 of R = La, in x ⩽ 0.43 of R = Pr and in x < 0.5 of R = Nd. The composition dependence of lattice parameters, magnetization and Curie temperature suggested that some changes occur at x = 0.2, 0.3 in Ce 1− x Pr x Fe 2 and x = 0.15, 0.2, 0.33 in Ce 1− x Nd x Fe 2. Mössbauer spectra of Fe show that the hyperfine field changes above and below x = 0.2. The increasing rate of magnetization of Ce 1− x Nd x Fe 2 with composition is 3.3 μ B in x < 0.3. These facts suggest that Nd in Ce 1− x Nd x Fe 2 is Nd 3+ in x ⩽ 0.2 and Nd 4+ 0.2 < x. The magnetization and Mössbauer data suggest that Pr in Ce 1− x Pr x Fe 2 is Pr 3+ in x ⩽ 0.2 and La in Ce 1− x La x Fe 2 is La 3+ and Ce 4+ in x ⩽ 0.2. The easy direction of magnetization is [1 0 0] in Ce 1− x R x Fe 2 ( R = La, Pr) and [1 1 0] in Ce 1− x Nd x Fe 2.

X-ray diffraction study of lattice parameters for layered compounds MxTaS2 (M=Tl or In)

The composition dependence of lattice parameters for layered compounds MxTaS2 (M=Tl or In, 0<x<0.6) has been determined by an X-ray diffraction method, in order to discuss the structural characteristics. Stage-2 and stage-1 phases for both compounds exist. A drastic change in the c-axis layer spacing was found for stage-1. Tl0.465TaS2, although there was no such anomaly in the composition dependence of the c-axis lattice parameter for In4TaS2.

Vapor quenched Ag 1- xFe x alloys: in situ Mössbauer studies

Metastable alloys of Ag 1- x Fe x ( x = 0.17, 0.30, 0.50, 0.54, 0.56, 0.80 and 1.0) were prepared by vapor condensation onto kapton substrates maintained at low temperature. The X-ray diffraction spectra of all Ag/Fe samples, with x<0.56, suggested the formation of a fcc structure with a very small grain size. The present work reports in situ Mössbauer measurements on Ag-Fe films and occurence of aging effects. All the spectra obtained at 5.5 K show magnetic hyperfine field distributions characteristic of disordered alloys and also texture effects. The results for composition dependence of lattice parameters and average hyperfine fields are compared with values reported in the literature for films prepared in different conditions.

ＰｂＯ‐ＲＯ‐Ｒ′Ｏ（Ｒ，Ｒ′＝Ｃａ，Ｓｒ，Ｃｕ）系状態図について

Equilibrium phase relationships for the pseudo-ternary systems PbO-CaO-CuO, PbO-SrO-CuO and PbO-CuO-SrO have been studied mainly by the X-ray diffraction method. The equilibrium phase diagram of the PbO-CaO-CuO system was drawn up at 700°C, 800°C and 850°C in air. The equilibrium phase diagram of the PbO-SrO-CuO system was determined at 700°C and 800°C in air. A part of phase diagram of the PbO-CaO-SrO system was drawn up at 800°C in air. At 800°C and 850°C, the regions of liquid or liquid+solids were determined in each systems. In the PbO-SrO-CuO system we found a new ternary solid solution. In the PbO-CaO-SrO system we found that (Ca1-xSrx2)2PbO4 was a solid solution of 0≤x≤1.0 at 800°C. The composition dependences of lattice parameters and decomposition point of a solid solution (CaxSr2)PbO4 were determined.

Phase diagram and metal distribution of the (Cr xTi 1− x) 3Se 4 system (0 ≤ x ≤ 1) with the Cr 3S 4-type structure

The phase diagram and metal distribution of the (Cr x Ti 1− x ) 3Se 4 system were studied by X-ray, neutron diffraction, and DTA measurements. The metal distribution of M′ M 2 X 4 with the Cr 3S 4-type structure, which was estimated from the composition dependence of lattice parameters in the solid solution ( M′ x M 1− x ) 3 X 4 system, was in good agreement with results from other measurements such as neutron diffraction and Mössbauer effect.

Composition dependence of lattice parameters and magnetic moments of f.c.c. Co1−xVxalloys

physica status solidi (a)Volume 22, Issue 2 p. K131-K133 Short Note Composition dependence of lattice parameters and magnetic moments of f.c.c. Co1−xVxalloys Y. Aoki, Y. Aoki Research Institute for Iron, Steel and Other Metals, Tǒhoku University, SendaiSearch for more papers by this authorM. Yamamoto, M. Yamamoto Research Institute for Iron, Steel and Other Metals, Tǒhoku University, SendaiSearch for more papers by this author Y. Aoki, Y. Aoki Research Institute for Iron, Steel and Other Metals, Tǒhoku University, SendaiSearch for more papers by this authorM. Yamamoto, M. Yamamoto Research Institute for Iron, Steel and Other Metals, Tǒhoku University, SendaiSearch for more papers by this author First published: 16 April 1974 https://doi.org/10.1002/pssa.2210220248Citations: 18AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume22, Issue216 April 1974Pages K131-K133 RelatedInformation

Phase transformations in the system GeSe-GeTe

Published results for the location and nature of phase transformations for alloys in the system GeSe-GeTe are not in agreement. High temperature X-ray diffraction and differential scanning calorimetry measurements now reported show two phase transformations. A rhombohedral-cubic transformation occurs at 370 ± 10° C in alloys based on the GeTe structure and with composition in the range 0–55 mol% GeSe. A ternary single phase region is formed by a peritectoid transformation at 450 ± 10° C in alloys with composition in the range 65–84 mol% GeSe. The temperature and composition dependence of lattice parameters have been determined for these alloys.