摘要
Ternary solid solutions of BiFeO_(3),GdFeO_(3)and BaTiO_(3)have been prepared by solid-state reaction method.Dielectric properties of these ceramics have been characterized in the tem-perature range between room temperature and 673 K and magnetic properties between 5 K and 300K.For the understanding of the multiferroic property,the relation between the crystal structures,magnetic transition and ferroelectric transitions with increasing temperature have been analyzed.All ceramic samples show single perovskite phase.When Ba content exceeds 0.2 wt%,the sintering ability is weakened and the phase structure of Bi_(1-x-y)Gd_(x)Ba_(y)Fe_(1-y)Ti_(y)O_(3)(with x=0.2 and y=0.1,0.2,0.3,0.4,0.5)solid solution changes from rhombohedral to tetragonal phase.The maximum ferroelectric transition temperature(T_(c))of this system was in the range 154-165℃with the dielectric constant peak of 6000 for y=0.5 at 100 kHz.Well-saturated piezoresponse hysteresis loops were observed for all compositions indicating room temperature ferroelectricity.With increasing Ba content(up to 0.3 wt%)the remanent magnetization M,increased and the coercive magnetic field decreased.
基金
Radheshyam Rai is grateful to the Foundation for Science and Technology of Portugal(FCT)fornan-cial support(Grant No.SFRH/BPD/38001/2007).
