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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. [ABSTRACT FROM AUTHOR]

The Bi5Ti3(Fe1−xCox)O15 (x = 0, 0.4, 0.5, 0.6, 0.7) ceramics synthesized by solid state reaction are investigated. The microstructures are Aurivillius phase with perovskite layered structure, which were analyzed by X-ray diffraction and Raman spectroscopy test. The temperature-dependent magnetization was systematically investigated for all samples with different Co doping ratios. The magnetization reversal effects were found in both ZFC and FC curves with one or two compensation temperature. And the compensate temperatures change with different x. The temperature-induced magnetization reversal may attribute to the competition between the super-exchange interaction of Fe3+-O-Fe3+ and Co3+-O-Co3+, the DM interaction of Fe3+-O-Co3+ chains, and the magneto-crystalline anisotropy. This competition can be affected by the contents of Fe ions to Co ions. The study of multiferroic material Bi5Ti3(Fe1−xCox)O15 ceramics with magnetization reversal effects has important significance in the Information Security Engineering, for the switch effect with different magnetizations and temperatures. [ABSTRACT FROM AUTHOR]