Crystal Structure and Properties of Complex Oxides (Nd,Ba)(Co,Fe)O3–δ

The homogeneity ranges and crystal structure of solid solutions of Nd1−x1BaxCo1−y1FeyO3−δ3 composition were detected. Depending on introduced barium concentration Nd1−x1BaxCo1−y1FeyO3−δ3 oxides have been crystallized in the orthorhombically distorted (x = 0.05, sp. gr. Pbnm), cubic (0.6 ≤ x ≤ 0.9, sp. gr. Pm-3m) perovskite structure or double perovskite structure NdBaCo2−x2FexO5+δ5 (0.0 ≤ x ≤ 1.4, sp. gr. P4/mmm). The dependencies of unit cell parameters versus composition of the Nd1−x1BaxCo1−y1FeyO3−δ3 solid solutions were obtained. It is shown that the values of oxygen nonstoichiometry in Nd1−x1BaxCo1−y1FeyO3−δ3, determined by a thermogravimetric method within the temperature range 298–1373 K in air, increased with the raise of barium and cobalt content. Average values of thermal expansion coefficients for the Nd1−x1BaxCo1−y1FeyO3−δ3 oxides (0.8 ≤ x ≤ 0.9 and 0.7 ≤ y ≤ 0.9) visibly increased with temperature from (13.5–14.5) × 10–6 K–1 at 300–700 K up to (23.2–26.2) × 10–6 K–1 at 700–1373 K.