Local Structure of Isovalent Doped Ca²⁺/Sr²⁺ → Ba Layered Perovskites Based on BaLaInO₄

Layered perovskites AA′BO 4 are promising electrolyte materials for electrochemical devices as sources of renewable and distributed energy. Creation of new materials with target properties requires knowledge of their local structure. In this paper, the influence of the nature and concentration of dopants (Ca 2+ and Sr 2+ ) during isovalent doping in the layered perovskite BaLaInO 4 has been investigated for the first time. Doping was found to change the crystal symmetry from orthorhombic (space group Pbca ) for the matrix BaLaInO 4 composition to tetragonal (space group I 4 /mmm ) for the doped Ba 1 − x Ca x LaInO 4 and Ba 1 − x Sr x LaInO 4 compositions. Doping results in the redistribution of bond lengths and changes the tilt angle of In‐containing polyhedra. These alterations in the crystal lattice increase the oxygen‐ionic conductivity values up to 1–1.5 orders of magnitude.