Crystal structure and multiferroic properties of Gd-substituted BiFeO ₃

Roomerature crystal structure, local ferroelectric, and magnetic properties of the Bi_1-xGd_xFeO₃ (x=0.1,0.2,0.3) polycrystalline samples have been investigated by x-ray diffraction, piezoresponse force microscopy, and magnetometry techniques. Performed measurements have revealed a sequence of the composition-driven structural phase transitions R3c→Pn2₁a (occurs at x∼0.1) and Pn2₁ a→Pnma (takes place within the concentrational range of 0.2<x<0.3). The latter structural transformation is attributed to the substitution-induced suppression of the polar displacements. Gd substitution has been shown to effectively induce the appearance of the spontaneous magnetization, thus indicating a promising way for improving multiferroic properties of antiferromagnetic BiFeO₃.