Oxygen nonstoichiometry and the thermodynamic and structural properties of double perovskites PrBaCo2 − x Cu x O5 + δ

Abstract

The special features of the structure, electrophysical properties, and oxygen nonstoichiometry of new double perovskites PrBaCo2 − x Cu x O5 + δ were studied. Within the homogeneity region with respect to copper 0 < x ≤ 1, solid solution samples had an orthorhombic structure (space group Pmmm) with the parameters a p × 2a p × 2a p , where a p ≈ 3.8 Å. The oxygen nonstoichiometry of PrBaCo2 − x Cu x O5 + δ changes as the copper content increases approximately as δ ≈ 0.85 − x/2. The content of oxygen was measured by coulometric titration over wide temperature and oxygen pressure ranges. The partial thermodynamic functions of labile oxygen were calculated and the limits of the thermodynamic stability of the solid solution were established.