Double perovskites REBaCo_2−xM_xO_6−δ (RE=La, Pr, Nd, Eu, Gd, Y; M=Fe, Mn) as energy-related materials: an overview

Abstract

Abstract This work, based on the experimental and theoretical research carried out by the authors during the last decade, presents an overview of formation, stability and defect thermodynamics, crystal structure, oxygen nonstoichiometry, chemical strain and transport properties of the double perovskites REBaCo 2−x M x O 6−δ (RE = La, Pr, Nd, Eu, Gd, Y; M = Fe, Mn). These mixed-conducting oxides are widely regarded as promising materials for various energy conversion and storage devices. Attention is focused on (i) thermodynamics of formation and disordering, oxygen nonstoichiometry, crystal and defect structure of the double perovskites REBaCo 2−x M x O 6−δ , as well as their thermodynamic stability and the homogeneity ranges of solid solutions, (ii) their overall conductivity and Seebeck coefficient as functions of temperature and oxygen partial pressure and (iii) the anisotropic chemical strain of their crystal lattice. The relationships between the peculiarities of the defect structure and related properties of the double perovskites are analysed.