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Based on phase equilibria, thermodynamic, and crystal structure data, the thermodynamic modeling of HfO2–La2O3–Al2O3 system is presented. Liquid phase is described by the modified quasichemical model considering the short-range ordering in liquid solution. Solid solutions are described by the ionic sublattice model considering respective crystal structure. The model (La3+, Hf4+)2(Hf4+, La3+)2(O2−, Va)6(O2−)1(Va, O2−)1 successfully describes the structure defect, homogeneity range, and thermodynamic property of pyrochlore solid solution. A set of optimized model parameters is obtained which reproduces most experimental data well. Isothermal sections, liquidus and solidus projections, and Scheil reaction scheme are constructed.

Based on the critical evaluation of available phase diagram, thermodynamic, and crystal structure data, the ternary Ti-C-O system is thermodynamically assessed using the Calculation of Phase Diagram method. Both binary Ti-C and Ti-O systems are reassessed to obtain the successful description of ternary Ti-C-O system for the first time. The liquid phase is described by the modified quasichemical model, which takes short-range ordering in liquid solution into account. All solid solutions are described using compound energy formalism. In particular, a completed solid solution between TiC x and TiO y with the excess solubilities of Ti, C, and O is accurately described with the (Ti, Va)1(C, O, Va)1 solution structure. The thermodynamic models with a set of optimized self-consistent model parameters can reproduce available reliable experimental data within experimental error limits. The results are also applied to the thermodynamic analysis of complex carbothermic TiO2 reduction process.

Thermodynamic assessment of the In-Ni-Sb ternary system has been performed using the CALPHAD technique. The phases ζ(Ni2In) and ζ(NiSb) with the same B8-type structure in the subbinary systems are modified using the same three-sublattice model: (Ni,Va)1/3(Ni,Va)1/3(Ni,X)1/3 (X = In, Sb), in order to give the continuous solid solution phase ζ in the In-Ni-Sb ternary system a better description. This modification is also made to the Gibbs free energy expression of the InSb phase. The parameters of the thermodynamic descriptions of the In-Ni-Sb ternary system are optimized on the basis of the three modified subbinary systems. A set of self-consistent thermodynamic parameters of the In-Ni-Sb system is obtained according to five isothermal sections and three vertical sections. Most of the experimental data can be satisfactorily reproduced by the present parameters. The liquidus projection and the invariant reactions are also presented. By simply considering the standards of melting temperature and thermodynamic stability, part of the ζ-phase is more suitable as a contact material to InSb semiconductor.

In the original article, there are three errors in the parameters listed under ω(NiIn): (Ni, Va)0.5(In, Ni)0.5 in Table␣II.

The knowledge of phase diagram and thermodynamic properties of the Si-Ta and Si-W systems is of technical importance for metallic contacts between Ta, W, and SiC in electrical and electronic devices. The phase diagram and thermodynamic properties of the Si-Ta and Si-W systems were assessed using the CALPHAD approach with available experimental data. The intermetallic compounds of the two systems were modeled as stoichiometric ones. A set of self-consistent thermodynamic parameters were obtained and the calculated phase equilibria were found to be in reasonable agreement with most experimental data. The calculated enthalpies of formation of the silicides in the Si-Ta and Si-W systems were compared with the reported values. The enthalpies of mixing of liquid at 2000 K in similar Si-transition metal systems were used for comparison in order to judge the rationality of the calculations. The assessed thermodynamic descriptions of the Si-Ta and Si-W binary systems will serve as part of the thermodynamic database for the Si-C-M (M: Ta and W) alloys.

According to measured experimental phase diagram data and thermodynamic data, the HoCl3-MCl (M = Na, K, Rb, Cs) phase diagrams were determined by the CALPHAD technique. The Gibbs energies of liquid phases in these systems have been optimized and calculated by the modified quasi-chemical model in the pair-approximation for short-range ordering. A series of thermodynamic functions have been optimized and calculated on the basis of an interactive computer-assisted analysis. The results show that the thermodynamic properties and phase diagrams are self-consistent. The optimized results for the systems are discussed.

Thermodynamic activities of aluminum in the iron–aluminum system were determined between about 720 and 850 K for the composition range between 23 and 33 at.% Al which includes the D0 3 -ordered nonstoichiometric intermetallic compound Fe 3 Al. For this purpose an electromotive force method with a single-crystal CaF 2 electrolyte was used, and the following cell arrangement was employed: (−)Pt|Ir|Al 0.85 Sn 0.15 , Na 3 AlF 6 |CaF 2 |Al 1± x Fe 3± x , Na 3 AlF 6 |Ir|Pt (+). Activities of iron were obtained by means of a Gibbs-Duhem integration for the same composition range. The results of the activity measurements were interpreted in terms of a statistical–thermodynamic model for nonstoichiometric phases with the D0 3 -superstructure based on defect formation energies from the literature. It was found that non-stoichiometry in Fe 3 Al is caused by anti-structure atoms on two of the three possible sublattices.

The Al2O3-SrO binary system has been studied using the CALPHAD technique in this paper. The modeling of Al2O3 in the liquid phase is modified from the traditional formula with the liquid phase represented by the ionic two-sublattice model as (Al3+, Sr2+) P ( $${\hbox{AlO}_{2}^{1-}}$$ , O2−) Q . Based on the measured phase equilibrium data and experimental thermodynamic properties, a set of thermodynamic functions has been optimized using an interactive computer-assisted analysis. The calculated results are compared with experimental data. A comparison between this system and similar systems is also given.

In this article, following a brief introduction concerning experimental measurements of surface and interfacial tensions, methods for calculating surface tension and surface segregation for binary, ternary, and multicomponent high-temperature melts based on Bulter's original treatment [1] and on available physical properties and thermodynamic data, especially excess Gibbs free energies of bulk phase and surface phase versus temperature obtained from thermodynamic databases using the calculation of phase diagram (CALPHAD) approach, with special attention to the model parameter, have been described. In addition, the geometric models can be extended to predict surface tensions of multicom-ponent systems from those of sub-binary systems. For illustration, some calculated examples, including Pb-free soldering systems and phase-diagram evaluation of binary alloys in nanoparticle systems are given. On the basis of surface tensions of high-temperature melts, interfacial tensions between liquid alloy and molten slag as well as molten slag and molten matter can be calculated using the Girifalco-Good equation [2]. Modifications are suggested in the Nishizawa's model [3] for estimation of interfacial tension in liquid metal (A)/ceramics (MX) systems so that the calculations can be carried out based on the sublattice model and thermodynamic data, without deliberately differentiating the phase of MX at high temperature. Finally, the derivation of an approximate expression for predicting interfacial tension between the high-temperature multi- component melts, employing Becker's model [4] in conjunction with Bulter's equation and interfacial tension data of the simple systems is described, and some examples concerning pyrometallurgical systems are given for better understanding.

Zinc vapor pressures over binary Pt–Zn alloys were determined in the composition range from 63 to 84 at.% Zn for temperatures between 840 –1150 K using an isopiestic method. The phase boundaries of four different phase fields in this composition range could be fixed based on the experimental data. Thermodynamic activities and partial molar enthalpies of zinc within these phase fields were derived from the vapor pressure data and the composition dependence of the zinc activity was calculated for 1023 K. The integral Gibbs energy at 1273 K was derived as a function of composition by Gibbs–Duhem integration, combining the activity data of the present investigation with earlier results from the literature.

By using the CALPHAD technique, an optimization of the binary YbCl3-AECl2 (AE=Mg, Ca, Sr, Ba) systems was carried out. From measured phase equilibrium data and experimental integral properties, the YbCl3-AECl2 phase diagrams were optimized and calculated. A set of thermodynamic functions was optimized based on an interactive computer-assisted analysis. The calculated phase diagrams and thermodynamic data are self-consistent.

Thermodynamic activities of indium were measured between 973 and 1273 K in the nonstoichiometric intermetallic compound Pt 3 In using an emf-method based on an oxygen conducting solid electrolyte. The variation of the lattice parameter with composition was determined by powder X-ray diffraction, and the corresponding results point to a considerably wider homogeneity range on the indium-rich side than previously reported. The results of the activity measurements are interpreted in terms of a statistical-thermodynamic model for L1 2 -phases considering four types of point defects, i.e. anti-structure atoms and vacancies on the platinum and indium sublattices. The energies of formation of the point defects at the stoichiometric composition are estimated from a curve fitting procedure yielding E f (Pt In )= E f (In Pt )=1.15 eV, assuming that E f V (Pt)= E f V (In)=2.0 eV. This results in a disorder parameter α ′=5·10 −6 at 1173 K which means that at the stoichiometric composition 0.002% of the indium sublattice sites are occupied by platinum atoms and 0.0007% of the platinum sites by indium atoms at this temperature.

Phase diagram and thermodynamic properties of the Ni-Ga system are assessed based on the CALPHAD approach, using all available experimental data and applying appropriate thermodynamic models. The liquid phase and the Ni-based solid solution (Ni) are treated as disordered solutions. The thermodynamic behavior of the ordered intermetallic compounds with appreciable ranges of homogeneity, Ni3Ga and NiGa, are described by a two-sublattice model, and the order-disorder transformation between Ni3Ga and fcc-(Ni) is also explicitly considered in this work. The other five intermetallic compounds are treated as stoichiometric line compounds. The phase diagram and the thermodynamic properties calculated from the optimized model parameters are in good agreement with most of the experimental data.

The phase relations in the Fe-rich region of the Nd-Fe-V system at room temperature have been investigated by means of powder X-ray diffraction. In the investigated composition region, two ternary phases: Nd(Fe1 - xVx)(12) (x = 0.125-0.167) and Nd-3(Fe1 - xVx)(29) (x = 0.064-0.091), and one pseudobinary phase: Nd-2(Fe1 - xVx)(17), (x = 0.000-0.061) were observed. Dependences of the lattice parameters on x for Nd(Fe1 - xVx)(12), Nd-3(Fe1 - xVx)(29) and Nd-2(Fe1 - xVx)(17) are presented. The preferred site occupation of V in Nd(Fe1 - xVx)(12) and Nd-2(Fe1 - xVx)(17) is deduced from the slope of a and c with V content. (C) 1999 Elsevier Science S.A. All rights reserved.

A new compound Gd 3 (Fe 0.665 Co 0.313 Ti 0.022 ) 29 with Nd 3 (Fe,Ti) 29 -type structure was synthesized. The crystal structure of Gd 3 (Fe 0.665 Co 0.313 Ti 0.022 ) 29 is refined by Rietveld analysis with a monoclinic lattice and a space group P2 1 /c derived from the CaCu 5 -type structure. The lattice constants a , b , c and the unit cell volume V are decreased by the substitution of cobalt for iron. The compound shows a high Curie temperature of 886 K and a planar anisotropy. The saturation magnetization of the compound is slightly higher than that of its parent compound Gd 3 (Fe 0.978 Ti 0.022 ) 29 .

Single-phase compounds Gd-3(Fe1-xTix)(29) (x=0.011 similar to 0.034) have been synthesized. Gd-3(Fe1-xTix)(29) crystallises in a monoclinic lattice with space group P2(1)/c, and the crystal structure is refined by the Rietveld technique based on X-ray powder diffraction data. Thermomagnetic analysis indicates that the Curie temperature of the compounds ranges from 517 K to 538 K. The saturation magnetizations of the Gd-3(Fe1-xTix)(29) (x=0.011, 0.022, 0.034) at 1.5 K are 103.6, 102.0 and 94.3 Am-2/kg, and the anisotropy fields at 1.5 K are 6.0, 6.2 and 6.4T, respectively. (C) 1998 Elsevier Science S.A.

A new estimating method for the standard enthalpy of formation of double oxide at 298.15 K is proposed. The standard enthalpy of formation can be obtained by adding the reaction enthalpy of the simple oxides combining into a double oxide to the sum of the standard enthalpies of formation of the simple oxides. When the reaction enthalpy relates to one mole of two simple oxides combining into a double oxide, the reaction enthalpy (ΔHo) can be predicted from a term, x1x2λ, where x1 and x2 are the mole fractions of the two simple oxides, and λ is a constant. If ΔHo is known for one double oxide, λ can be calculated. Then, ΔHo of other double oxides formed from these two simple oxides can be predicted. If no ΔHo values is known, λ can be estimated from the electronegativities of the component elements.

An assembly for performing electromotive force (EMF) measurements using either a CaF2 single crystal or a MgO partially stabilized zirconia as a solid-state electrolyte has been constructed. Heat capacities of member complex oxides in the Sm-Ba-Cu-O system were measured by an adiabatic scanning calorimeter. From the EMF data, the standard Gibbs energies, standard enthalpies of formation, standard entropies, and decomposition pressures of the complex oxides were calculated. The standard Gibbs energies of reaction of complex oxides from relevant simple oxides Sm2O3, BaO, and CuO were derived. It was found that all complex compounds in this system were thermodynamic stable. The tendency of the thermodynamic stability of the solid solution compound Sm1+x, Ba2−xCu3Oy decreases with the solubility x from 0 to 0.4.

The BaB2O4-BaF2-2NaF-NaB2O4 reciprocal system has been investigated by combination of experimental measurements with theoretical calculation. The Na2B2O4-2NaF binary and Na2B2O4-BaF2 pseudo-binary phase diagrams are measured by means of DTA and X-ray diffraction. The thermodynamic functions for all sub-binary systems are derived from measured phase diagrams and thermodynamic data by CAL-PHAD technique, and the sub-binary phase diagrams are calculated according to phase equilibrium principle. Then, the thermodynamic functions for sub-binary systems are extrapolated to the BaB2O4-BaF2-2NaF-Na2B2O4 reciprocal system, and the phase diagram of the reciprocal system is calculated. The calculated phase diagrams are verified by additional experiments. (C) 1996 Academic Press, Inc.

The subsolidus phase relations of the Nd{sub 2}O{sub 3}-Pr{sub 6}O{sub 11}-CuO ternary system sintered in air at 950{degrees}C have been investigated by X-ray powder diffraction. The system can be divided into one ternary phase region and three binary phase regions. The solid solution Nd{sub 2-x}Pr{sub x}CuO{sub 4-{delta}} has been observed to exist over the composition region 0 < x < 2. The solid solution has a tetragonal structure, and its lattice parameters increase linearly with the increasing of the praseodymium content.

The variation of oxygen content with cation substitution for several types of high-T(c) copper oxide solid solutions has been analyzed in terms of both theoretical derivations and experiments. It has been found that for continuous solid solutions the oxygen content varies with substitution in a linear manner over the entire substitution region, while for discontinuous solid solutions the first derivatives of the oxygen content with respect to substitution is discontinuous at the solid solution limit. For the latter, the oxygen content varies in the same way as continuous solid solutions with substitution within the solution limits. However, beyond the solid solution limits, oxygen contents vary with substitution either in a linear manner but with different slope or in a curvy manner, depending on the properties of the component elements of the solid solutions. Therefore, we can determine the solid solution lin-sit or, rather, detect the existence of minor amounts of impurities from the plot of the variation of oxygen content with substitution. The determination of the oxygen content by iodometric titration have verified the above conclusions. The solid solution limits determined by our method are in good agreement with those by powder X-ray diffraction. In some cases, the present method has advantages over conventional powder X-ray diffraction for determining the solid solution limits.

The subsolidus phase relations of Nd2O3-SrO-CuO ternary system sintered in air at 950-1000-degrees-C have been investigated by X-ray powder diffraction. The system can be divided into 13 three-phase regions and five two-phase regions. In this system there exist at least four compounds and their solid solutions: Nd2SrCu2O6, Nd1+xSr2-xCu2O6 (0 less-than-or-equal-to x less-than-or-equal-to 0.4), Nd2-xSrxCuOy (1.2 less-than-or-equal-to x less-than-or-equal-to 1.5) and NdxSr3-xCu5Oy (0 less-than-or-equal-to x less-than-or-equal-to 1.5). None of these compounds are superconducting above 4.2 K.

ZnO nanorods with diameters of 10–200 nm were fabricated through a simple gas reaction method. They were characterized by means of powder X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray (EDX) spectroscopy and transmission electron microscopy (TEM). FE-SEM and TEM images showed that the product was composed of nanorods with lengths from several to tens microns. XRD and EDX indicated that the nanorods were hexagonal ZnO.

In this paper the cyclic voltammetry equations for a reversible process with an insoluble product were derived using a simple mathematical approach. The electrode processes on molybdenum and nickel electrodes were investigated. The results show that yttrium can form an intermetallic compound with nickel. From the energy spectrum and X-ray diffraction, it is shown that the intermetallic compound is Ni2Y (723 K).

β-Ga 2 O 3 nanorods with diameters of 10–60 nm were synthesized through a simple gas reaction method and were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), selected area electron diffraction (SAED) and high-resolution transmission electron microscopy (HRTEM). The SEM image showed that most of the nanorods were straight. XRD, SAED and HRTEM indicated that the nanorods were monoclinic Ga 2 O 3 single crystals.

GaN nanorods with diameters of 10–45 nm were formed through a simple sublimation method. They were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), selected area electron diffraction (SAED) and high-resolution transmission electron microscopy (HRTEM). SEM images showed that the nanorods were straight. XRD, SAED and HRTEM indicated that the nanorods were wurtzite GaN single crystals.

The phase relation in the Fe-rich region of the Gd-Fe-Ti system at 1373 K has been investigated by means of x-ray diffraction and the phase-disappearing method. In the investigated composition region, four ternary phases: GdFe11Ti, GdFe9Ti2, Gd(Fe1-xTix)(9) (x approximate to=0.062), Gd-3(Fe1-xTix)(29) (x=0.0111-0.0339), one pseudobinary phase: Gd-2(Fe1-xTix)(17) (x=0.0000-0.0511) and three binary phases: Gd6Fe23, Fe2Ti and GdFe3, are observed. Dependence of the lattice parameters on Ti content (x) in Gd-2(Fe1-xTix)(17) and Gd-3(Fe1-xTix)(29) is reported. (C) 1998 Elsevier Science S.A.

The phase diagram of the EuI{sub 2}-KI binary system was studied by differential thermal analysis (DTA) and X-ray powder diffraction (XRD). The phase diagram of the EuI{sub 2}-KI system shows the existence of one congruently melting compound, KEu{sub 2}I{sub 5}, and one incongruently melting compound, K{sub 4}EuI{sub 6}. There are two eutectic points located at 465 C, 20 mol% KI and 439 C, 60 mol% KI, respectively.