X-ray diffraction and magnetization studies of BiFeO_3 multiferroic compounds substituted by Sm~(3+), Gd~(3+), Ca~(2+)

摘要

The multiferroic compounds Bi_(0.9)Sm_(0.1)FeO_3, Bi_(0.9)Gd_(0.1)FeO_3, Bi_(0.9)Ca_(0.1)FeO_3, Bi_(0.9)Sm_(0.05)Ca_(0.05)FeO_3, and Bi_(0.9)Gd_(0.05)Ca_(0.05)FeO_3 were prepared by the conventional ceramic method and were characterized by X-ray diffraction, vibrating sample magnetometry, and differential scanning calorimetry. The compounds were found to have the rhombohedral perovskite-like structure, accompanied by a small residual Bi_2Fe4O_9 impurity phase. Magnetic hysteresis loops with enhanced remnant magnetization and coercive field were obtained for the Gd-containing compounds. The improvement of magnetic behavior of the Gd-containing compounds is thought to arise mainly from the partial suppression of the spiral spin structure and the stronger interaction between magnetic ions. The magnetic transition temperatures of the compounds were found to be in the range 300-310 °C.