Structure and Physicochemical Properties of NdBa1 – xCaxFeCo0.5Cu0.5O5 + δ Solid Solutions (0.00 ≤ x ≤ 0.40)

NdBa1 – xCaxFeCo0.5Cu0.5O5 + δ solid solutions of double perovskites were obtained by solid-phase reactions, and their crystal structure, oxygen nonstoichiometry (δ), and electrotransport properties (electrical conductivity, thermal emf) were studied. These solid solutions are p-type semiconductors and crystallize in the tetragonal system (space group P4/mmm) at 0.0 ≤ x ≤ 0.05 and in the orthorhombic system (space group Pmmm) at 0.10 ≤ x ≤ 0.40. Partial substitution of calcium for barium in NdBaFeCo0.5Cu0.5O5 + δ leads to a decrease in the unit cell size, oxygen nonstoichiometry, and electrical conductivity of the formed solid solutions and in an increase in their thermal emf. The activation energies of electrotransport processes, weighted mobility, and concentration of charge carriers in the studied materials were calculated.