Electronic and Magnetic States of Iron Ions in (Bi1-xSrx)FeO3-y Multiferroic Perovskites
The mixed perovskites (Bi1-xSrx)FeO3-y (x = 0.07, 0.14, 0.25 and 0.50) were studied by 57Fe Mössbauer spectroscopy in the temperature range 87–700 K. The samples were prepared by conventional ceramic technology with 10% 57Fe isotope enrichment. X–ray diffraction measurements showed that the samples were single-phase and had a rhombohedral structure at x = 0.07 and a cubic one at x = 0.14-0.50. As the strontium content x increases, the Neel temperature TN(x) increases from 640 K (x = 0) to 670 K (x = 0.25) and then decreases to 637 K (x = 0.5). The similar dependence on x was found for the hyperfine field values B(x) at T = 87 K. The experimental Mössbauer spectra are satisfactorily described by three to four Fe3+ states with the room temperature isomer shift values in the range 0.17-0.43 mm/s, which correspond to the iron sites with 4, 5 and 6 oxygen neighbours.
V. M. Cherepanov and V. S. Pokatilov, "Electronic and Magnetic States of Iron Ions in (Bi1-xSrx)FeO3-y Multiferroic Perovskites", Solid State Phenomena, Vols. 152-153, pp. 89-92, 2009