Crystal structures and Mössbauer spectra of LaFe_1−xMn_xO₃ and LaFe_1−xCo_xO₃ (x = 0 to 0.9)

The crystal structures and Mössbauer spectra of various mixed oxides LaFe_1−xMn_xO₃ and LaFe_1−xCo_xO₃ (x = 0 to 0.9) are determined and measured at room temperature. The results indicate that the crystal structure of both the La–Fe–Mn–O and the La–Fe–Co–O systems vary with the relative content of manganese and cobalt in the compounds. Mössbauer parameters of the ⁵⁷Fe nucleus in these compounds, such as isomer shift, electric quadrupole splitting, linewidth, and internal magnetic field, are obtained from the experimental spectra. Various possible substitutions of Mn and Co ions for Fe ions in the lattice and the effect of the Mn and Co ions on the Mössbauer spectra of the ⁵⁷Fe nucleus in these compounds are discussed. Both manganese and cobalt ions in these compounds are mainly in a low spin state. The change in the crystal structure is in accordance with the change in the magnetic behaviour of these compounds.