Enhancement of magnetization and dielectric properties of chromium-doped BiFeO₃ with tunable morphologies

Multiferroic BiFe_{1 - x}Cr_xO ₃ (x = 0.025, 0.05, 0.075, and 0.1) is prepared by the hydrothermal method. Samples are systematically characterized by X-ray diffraction, Rietveld refinement, SEM, dielectric and magnetic measurements. It is found that the lattice parameters, the morphology and the size of the obtained particles strongly depend on the Cr doping level. The lattice parameters a and c and the Fe-O (1) bond lengths decrease, while the Fe-O (2) bond lengths increase, as x values rise from 0.025 to 0.1. The particle morphology changes from spherical shape for pure BiFeO₃ to octahedral shape for x = 0.1. The dielectric constant and the magnetization increase greatly with the increase of the Cr doping level. Both the M-T and the M-H results reveal that the Cr doping enhances the ferromagnetic state in the doped BiFeO₃. The possible reasons for the enhanced magnetic and dielectric properties are discussed briefly.