Influence of Y-doping on structure, microwave dielectric and magnetic behaviors in BiFeO3

Powder samples of Bi1−xYxFeO3 (BFO, x=0, 0.02, 0.05 and 0.1) were prepared by sol-gel method in this paper. The BFO is crystallized in rhombohedrally distorted perovskite structure with space group R3c. Y-doping generates structural evolution in BFO toward orthorhombic Pnma structure due to the adequate substitution of Bi3+. In 12-18 GHz, both the dielectric constant and the loss tangent increase with Y-doping, but a compositional independent dielectric loss peak is observed at about 15.5 GHz. The leakage loss is reduced due to the decrease of oxygen vacancies. Main contribution of the dielectric loss is ascribed to dipole polarization. During the doping process, the improved prevention of leakage current enhances the polarization of BFO samples whereas the magnetism is enhanced by the suppression of the long-range spiral spin modulation.