57Fe Hyperfine Parameters in Bi1-xLaxFeO3 (X=0-1)

Fe-57 Mossbauer study of the Bi1-xLaxFeO3 (x=0, 0.1, 0.2, 0.61, 0.9, 1.0) perovskites has been performed at room temperature (RT) to analyze influence of the space spin-modulated magnetic structure (SSMMS) on parameters of hyperfine interactions, the valence and magnetic states of iron ions, SSMMS in perovskites BiFeO3 and Bi0.9La0.1FeO(3) leads to a specific distribution of hyperfine fields P(H) with two peaks. Substitution La for Bi more than x = 0.2 destroys SSMMS and P(H) corresponds to a distribution for a homogeneous spin structure. Concentration dependences of hyperfine fields (H), isomer (delta) and quadrupole (epsilon) shifts were measured. Due to the isomer shift values the iron ions are in the trivalent state. The local magnetic moments mu(Fe) on Fe+3 ions were determined in these perovskites.