Hyperfine Interactions of 57Fe Nuclei in ScCo1–xFexO3 (x = 0.05, 0.4) Substituted Cobaltites

Resumo

The Mössbauer study of ⁵⁷Fe nuclei in Sc_1–yCo_1–xFe_xO_3–3/2y (x = 0.05, 0.4; y = 0.1, 0.2) cobaltites has been reported. Mössbauer spectra, as well as calculations of the parameters of the electric field gradient tensor, have shown that Fe³⁺ cations not only occupy characteristic for them positions with octahedral oxygen coordination, but also partially substitute Sc³⁺ cations in ScO_n polyhedra with a large coordination number (n = 8–12). The character of distribution of iron cations over two positions depends on the composition of studied cobaltites. In contrast to Co³⁺ cations, Fe³⁺ cations in both positions are stabilized in a highspin state (S = 5/2). The analysis of the magnetic hyperfine structure of ⁵⁷Fe spectra measured at T < T_N has shown that magnetically ordered iron-rich microclusters can be formed in the octahedral sublattice of the Sc_0.9Co_0.6Fe_0.4O_2.85 and Sc_0.8Co_0.6Fe_0.4O_2.7 cobaltites. The most fraction of iron in Sc_0.9Co_0.95⁵⁷Fe_0.05O_2.85 remains in the paramagnetic state down to the lowest temperatures.