Mössbauer study of cation substitution effect on magnetic phase transitions in (1−x)BiFeO3−xAFe0.5B0.5O₃(A=Ba, Sr, Pb; B=Nb, Sb) solid solutions

Ceramic samples of ([Formula: see text])BiFeO[Formula: see text]PbFe[Formula: see text]Sb[Formula: see text]O 3 (BFO–xPFS), ([Formula: see text])BiFeO[Formula: see text]SrFe[Formula: see text]Sb[Formula: see text]O 3 (BFO–xSFS) where ([Formula: see text]), ([Formula: see text])BiFeO[Formula: see text]BaFe[Formula: see text]Nb[Formula: see text]O 3 (BFO–xBFN) and ([Formula: see text])BiFeO[Formula: see text]SrFe[Formula: see text]Nb[Formula: see text]O 3 (BFO–xSFN) where ([Formula: see text]) solid solutions with a perovskite structure were obtained. Mössbauer studies have shown that the Neel temperature [Formula: see text] concentration dependences of the systems studied are in good agreement with [Formula: see text] calculated under the assumption of the ordered distribution of Fe[Formula: see text] and nonmagnetic Sb[Formula: see text] ions in the lattice. The [Formula: see text] values obtained for BFO–xBFN and BFO–xPFS are close to the values, calculated for cases of the disordered and ordered distribution of Fe[Formula: see text] and nonmagnetic Nb[Formula: see text] and Sb[Formula: see text] ions in the lattice, respectively. The [Formula: see text] values of BFO–xSFN and BFO–xSFS are in the range between the calculated values for ordered and disordered cases. Moreover the anomaly on the [Formula: see text] dependence for the BFO–xBFN and BFO–xSFN systems was found near [Formula: see text]. This anomaly is most likely related to the destruction of the magnetic super exchange via the empty 6p state of Bi[Formula: see text] ions.