Transmission electron microscopy study of multiferroic (Bi1-xLax)FeO3-PbTiO3 with x=0.1, 0.2, and 0.3

Microstructural features of the solid solution series of 0.45(Bi1-xLax) FeO3-0.55PbTiO(3) with x=0.1, 0.2, and 0.3 have been investigated by transmission electron microscopy. The experimental results demonstrate that substituting La for Bi leads to a rich variety of structural phenomena: the typical crystal structure changes gradually from tetragonal (T) to rhombohedral (R) with the increase of La content, all three samples have notable features of coexistence of T and R phases, and two remarkable superstructures, (1/2 1/2 0) and (1/2 1/2 1/2), often appear in x=0.2 and 0.3 samples. The (1/2 1/2 0) superstructure is likely to be an intermediate state bridging the T-R phase transition. Typical twin domains and ferroelectric polarization in these materials have been extensively discussed. (C) 2007 American Institute of Physics.