Hyperfine Interactions of [sup.57]Fe Nuclei in Sc[Co.sub.1-x][Fe.sub.x][O.sub.3] Substituted Cobaltites

The Mossbauer study of [sup.57]Fe nuclei in [Sc.sub.1-y][Co.sub.1-x][Fe.sub.x][O.sub.3-3/2y] (x = 0.05, 0.4; y = 0.1, 0.2) cobaltites has been reported. Mossbauer spectra, as well as calculations of the parameters of the electric field gradient tensor, have shown that [Fe.sup.3+] cations not only occupy characteristic for them positions with octahedral oxygen coordination, but also partially substitute [Sc.sup.3+] cations in Sc[O.sub.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 [Co.sup.3+] cations, [Fe.sup.3+] cations in both positions are stabilized in a highspin state (S = 5/2). The analysis of the magnetic hyperfine structure of [sup.57]Fe spectra measured at T < [T.sub.N] has shown that magnetically ordered iron-rich microclusters can be formed in the octahedral sublattice of the [Sc.sub.0.9][Co.sub.0.6][Fe.sub.0.4][O.sub.2.85] and [Sc.sub.0.8][Co.sub.0.6][Fe.sub.0.4][O.sub.2.7] cobaltites. The most fraction of iron in [Sc.sub.0.9][Co.sub.0.95][sup.57][Fe.sub.0.05][O.sub.2.85] remains in the paramagnetic state down to the lowest temperatures.