Structural Transition and Magnetic Property of Bi_1-xYb_xFeO₃

Bi_1-xYb_xFeO₃(0≤x≤0.2) powders have been synthesized using a sol-gel method. The X-ray diffraction data show a structural transition from the rhombohedral R3c phase to the orthorhombic Pnma phase between x=0.1 and 0.125, which should induce a ferroelectric- paraelectric transformation. The phase transition is also proven by the Raman spectroscopy. A moderate signal on magnetization appears to illustrate the enhancement of magnetization at the transformation boundary, which is suggested to be the destruction of the spin cycloid structure at low concentration. The appearance of antiferromagnetic ordering is proposed to account for the afterward reduction of the magnetization at high concentration.