Effects of La/Ho co-substitution on structure and multiferroic characteristics of BiFeO3 ceramics.

The effects of La/Ho co-substitution on multiferroic characteristics were investigated for BiFeO3 ceramics together with structure evolution. The symmetry in Bi1−x(La0.65Ho0.35)xFeO3 ceramics changed from R3c to Pna21 and finally Pbnm with increasing x. Ferroelectricity was significantly improved with La/Ho co-substitution, and Pr reached the maximum of 30.9 μC/cm2 at 160 kV/cm at x = 0.16, where the R3c/Pna21 morphotropic phase boundary was determined. The weak ferromagnetism was released as the symmetry changed from R3c to Pna21, and subsequently the saturated M–H loop could be determined gradually with increasing x, and Mr increased continuously. The electric field-controlled magnetism could be characterized by the significant magnetism variation due to the electric field-induced transition of Pna21/R3c, which occurred during the poling process, and this transition became reversible by the help of annealing after poling. Compared with the situation of Bi1−xNdxFeO3 (the ion radius is the same as the effective one of La0.65Ho0.35), the present co-substituted BiFeO3 ceramics exhibited superior electric field-induced transition of Pna21/R3c with a maximum change rate of 47.03% in remanent magnetization under an electric field, which enhanced the magnetoelectric effect. [ABSTRACT FROM AUTHOR]