Crystal structure, electronic structure, and magnetic properties of bismuth-strontium ferrites

Bi1-xSrxFeO3 compounds were studied by X-ray diffraction, Mossbauer effect, and magnetic measurements. The replacement of trivalent Bi by divalent Sr lends to a change of the lattice symmetry from the rhombohedrally distorted perovskite of BiFeO3 to the cubic one of SrFeO2.97 and results in oxygen deficiency in the lattice. The oxygen-deficient Bi1-xSrxFeO3 compounds have two different crystal sites for iron ions, i.e., the octahedral sites and the oxygen-deficient tetrahedral sites. However, the iron ions both on the octahedral sites and the tetrahedral sites are in the trivalent state. Bi1-xSrxFeO3 exhibits the presence of both antiferromagnetic and weak ferromagnetic interactions simultaneously. As thr Sr content increases, the susceptibility and magnetization of Bi1-xSrxFeO3 decrease. (C) 2001 Elsevier Science B.V. All rights reserved.