Synthesis, Crystal and Electronic Structures, and Thermodynamic Characteristics of BaCe_(1-x)In_xO_(3-x/2) Solid Solutions

摘要

New perovskite oxide phases BaCe_(1-x)In_xO_(-x/2)(x = 0.1-0.8) (space group Pbnm) have been synthesized. The unit cell volume of the resulting solid solutions monotonically decreases with an increase in the degree of substitution of indium for cerium due to the contraction of octahedra in perovskite blocks. The thermodynamic stability of the compound BaCe_(0.75)In_(0.25)O_(2.875) was studied by the solution calorimetry method, and barium cerates were shown to be thermodynamically stable with respect to binary oxides at room temperature. The structure of occupied and vacant states in BaCe_(1-x)In_xO_(3-x/2) was determined on the basis of X-ray emission, absorption, and photoelectron spectra, and the energy gap was estimated at ～2 eV.