Bi2FeMnO6 ceramics were prepared under atmospheric pressure and a high pressure of 1–6 GPa. The effects of different high‐pressure syntheses on the microstructures were analyzed by X‐ray diffraction and Rietveld refinement, scanning electron microscopy–energy‐dispersive spectroscopy, X‐ray photoelectron spectrometer, and Raman spectroscopy test. The temperature dependence of magnetization was systematically investigated for all samples. There was a transition from rhombohedral R3c structure to orthorhombic phase Pnam with increasing synthetic pressure. The samples synthesized under atmospheric pressure are rhombohedral R3c with antiferromagnetic (AFM) magnetic temperature (M–T curves). The samples synthesized under a high pressure of 5–6 GPa are orthorhombic phase Pnam with the magnetization reversal effect, whereas the lower high‐pressure (1–3 GPa) synthesized samples might be in the transitional area between them. This structural transformation is accompanied by the transformation from normal AFM M–T curves to a typical magnetization reversal effect. The relationship between the lattice distortion and the internal magnetic competition mechanism of the material was discussed. The existence of magnetization reversal in these systems may ascribe to the competition between the single‐ion magnetic anisotropy and the Dzyaloshinsky–Moriya interaction.

We report results from a study of the crystal structure of strontium-doped BiFeO3 using neutron powder diffraction and the Rietveld method. Measurements were obtained over a wide range of temperatures from 300–800 K for compositions between 10–16% replacement of bismuth by strontium. The results show a clear variation of the two main structural deformations – symmetry-breaking rotations of the FeO6 octahedra and polar ionic displacements that give ferroelectricity – with chemical composition, but relatively little variation with temperature. On the other hand, the antiferromagnetic order shows a variation with temperature and a second order phase transition consistent with the classical Heisenberg model. There is, however, very little variation in the behaviour of the antiferromagnetism with chemical composition, and hence with the degree of the structural symmetry-breaking distortions. We therefore conclude that there is no significant coupling between antiferromagnetism and ferroelectricity in Sr-doped BiFeO3 and, by extension, in pure BiFeO3.