Weidong Zhuang

Thermodynamic evaluation of the Cu-R (R: Ce, Pr, Nd, Sm) binary systems

The phase diagrams and thermodynamic properties of the Cu-R (R: Ce, Pr, Nd, Sm) systems are reevaluated on the basis of all available experimental data, including the enthalpies of mixing reported recently. The Redlich-Kister polynomial with two or three terms is used to describe the excess Gibbs energies of liquid phases in the Cu-R systems. All intermediate phases are treated as stoichiometric, and their Gibbs energies of formation are optimized. Based on the optimized thermodynamic parameters, phase diagrams and thermodynamic properties of the Cu-R systems are calculated and compared with the experimental results. The optimized parameters seem to be in good agreement with the experimental data and might represent the regularity and systematic variation of these systems.

Estimation of the standard enthalpy of formation of double oxide

Abstract 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.

Subsolidus phase relations in the system BaOB2O3P2O5

Abstract The subsolidus phase relations in the system BaOB 2 O 3 P 2 O 5 were determined. The system can be divided into 16 three-phase regions. There are nine binary compounds and three ternary compounds in this system.

Phase relations in the system La2O3B2O3P2O5

Abstract The subsolidus phase relations in the system La 2 O 2 B 2 O 3 P 2 O 5 were investigated. The system can be divided into 12 three-phase regions. There are nine binary compounds and one ternary compound in this system. The ternary compound La 7 O 6 (BO ? )(PO 4 ) 2 has a monoclinic structure, space group P 2 1 /n, with lattice constants a = 7.0172A, b = 17.9125A, c = 12.6500A, β = 97.516°, V = 1576.39A, and Z = 4.

Crystal structure and vibrational spectra studies of stillwellite compounds NdBSiO5

Abstract The crystal structure of the stillwellite compound NdBSiO 5 has been studied by a combination of X-ray powder diffraction (XRD) and vibration spectroscopic techniques. The structure is refined by Rietveld technique, which indicates that the structural units of this compound are SiO 4 and BO 4 tetrahedra as well as irregular rare earth polyhedra. The Raman and infrared spectra of this compound have been investigated, and its interpretation is discussed on both theoretical and experimental bases. Assignments have been deduced from the systematic investigation of natural compounds and isotopic species with the help of isotopic shift data of 10 B- 11 B.