Probe Mössbauer Spectroscopy of BiNi0.9657Fe0.04O3

Resumo

This paper presents results of a ⁵⁷Fe probe Mössbauer spectroscopy study of the BiNi_0.96⁵⁷Fe_0.04O₃ nickelate. The spectra measured above its TN demonstrate that Fe³⁺ cations heterovalently substitute for Ni²⁺ nickel (←Fe³⁺), being stabilized on four sites of the nickel sublattice in the structure of BiNiO₃. Calculations in an ionic model with allowance for monopole and dipole contributions to the electric field gradient indicate that the parameters of electric hyperfine interactions between ⁵⁷Fe probe atom nuclei reflect the specifics of the local environment of the nickel in the structure of the unsubstituted BiNiO₃ nickelate. Below T^N, Mössbauer spectra transform into a complex Zeeman structure, which is analyzed in terms of first-order perturbation theory with allowance for electric quadrupole interactions as a small perturbation of the Zeeman levels of the ⁵⁷Fe hyperfine structure, as well as for specific features of the magnetic ordering of the Ni²⁺ cations in the nickelate studied.