Influence of Oxygen Nonstoichiometry on the Structural Stability of La 1– x Ca x Mn 0.5 Co 0.5 O 3 Complex Oxides ( x = 0.2–0.6) Subjected to Heat Treatment in He

The La 1– x Ca x Mn 0.5 Co 0.5 O 3 solid solutions ( x = 0.2-0.6) are prepared by the Pechini method and characterized by a number of physical and chemical methods. It is shown that the oxygen nonstoichiometry in the samples significantly increases with increasing number of calcium cations in the La sublattice. The thermal analysis of the samples shows that the lattice oxygen is released at ~600 °C for all samples and that its amount increases with increasing calcium content. The in situ powder XRD data obtained in the He atmosphere indicate that the studied solid solutions with x ≥ 0.4 are unstable under these conditions and may exhibit partial structural destruction and that the AB O 3 complex oxide in the system with x = 0.6 transforms into a phase characterized by the A 2 B O 4 structural type of the Ruddlesden–Popper series.