Thermodynamic Properties of Mixed Oxides in the CaO-SrO-Bi2O3-Nb2O5-Ta2O5 System

Abstrakt

A review on stoichiometric mixed oxides in the CaO-SrO-Bi₂O₃-Nb₂O₅-Ta₂O₅ system. Some of the oxides find applications as materials for electronics. Various processes for preparation of the oxides, both in the bulk form (polycrystalline powders, single crystals) and as thin-layer materials, are described. Experimental methods of determination of thermodynamic properties of the mixed oxides are treated and possibilities of obtaining missing data using empirical estimation methods or theoretical calculations are mentioned. The values of fundamental thermodynamic functions given in literature are collected. Applications of the additive Neumann-Kopp rule in estimation of temperature dependences of heat capacities and empirical entropy-volume correlations as well as in prediction of molar entropies of mixed oxides are discussed.