Crystal structure, oxygen nonstoichiometry and thermal expansion of the layered NdBaCo2−xМxO5+δ (M = Ni, Cu)

• The crystal structural of oxides was studied by X-ray diffraction.
• Oxygen nonstoichiometry of oxides is investigated.
• The average thermal expansion coefficients for the samples are calculated.

The homogeneity range and crystal structure of the NdBaCo2−xMxO5+δ (0.0 ⩽ x ⩽ 0.5 for M = Ni and 0.0 ⩽ x ⩽ 1.1 for M = Cu) solid solutions were determined by X-ray diffraction. The crystal structure of the NdBaCo2−xMxO5+δ was described as tetragonal (sp. gr. P4/mmm). The structural parameters were refined using Rietveld full-profile analysis. It was shown that parameter a remains practically constant while parameter c gradually increases with the increase of nickel or copper content. The changes of oxygen content in NdBaCo2−xMxO5+δ versus temperature were determined by thermogravimetric analysis. Gradual substitution of cobalt by copper or nickel leads to the decrease of oxygen content. The average thermal expansion coefficients for the NdBaCo2−xMxO5+δ (M = Ni, Cu) samples were calculated within the temperature range 298–1273 K in air. The chemical stability of complex oxides NdBaCo2−xMxO5+δ (M = Ni, Cu) in contact with the electrolyte materials Ce0.8Sm0.2O2−δ and Zr0.85Y0.15O2−δ were investigated within the temperature range 1173–1373 K in air.