Phase equilibria, crystal structure at 1373 K and properties of complex oxides in the Nd–Co–Fe–O system

• Published in: Russian journal of inorganic chemistry 2017-08, Vol.62 (8), p.1090-1098
• Main Authors: Aksenova, T. V., Elkalashy, Sh. I., Urusova, A. S., Cherepanov, V. A.
• Format: Article
• Language: English
• Subjects: Chemistry; Chemistry and Materials Science; Cobalt; Cross-sections; Crystal structure; Electrical resistivity; Inorganic Chemistry; Iron; Mathematical analysis; Oxides; Phase equilibria; Physicochemical Analysis of Inorganic Systems; Rietveld method; Solid electrolytes; Thermal expansion
• ISSN: 0036-0236; 1531-8613
• DOI: 10.1134/S0036023617080022

Phase equilibria in the Nd–Co–Fe–O system were systematically studied at 1373 K in air. The homogeneity range and crystal structure of solid solution NdCo 1–x Fe x O 3 (0.0 ≤ x ≤ 1.0) have been studied by the X-ray powder diffraction method. The structural parameters of complex oxides have been refined by the full-profile Rietveld method. It was shown that all oxides reveal practically stoichiometric oxygen composition within the entire temperature range under investigation. The values of thermal expansion coefficients for the cobaltites NdCo 1–x Fe x O 3 (x = 0.3, 0.7) have been calculated within the wide temperature range in air. Chemical stability of NdCo 1–x Fe x O 3 (x = 0.3, 0.7) in respect to the solid electrolyte materials (Ce 0.8 Sm 0.2 O 2–δ and La 0.88 Sr 0.12 Ga 0.82 Mg 0.18O3-δ ) was examined. Electrical conductivity of NdCo 1–x Fe x O 3 (x = 0.3, 0.7) was measured as a function of temperature within the range 300–1373 K in air. It was shown that substitution of cobalt for iron leads to the decrease of conductivity. The isothermal-isobaric cross-section of the phase diagram for the Nd–Co–Fe–O system at 1373 K in air has been presented.