Ferroelectric Distortion in Bi4Ti3O12 Studied by Neutron Powder Diffraction
Crystal structures of Bi4Ti3O12 ferroelectrics have been investigated by high-temperature neutron powder diffraction study. The ferroelectricity in Bi4Ti3O12 is shown to originate from the in-plane displacement of TiO6 octahedra with respect to heavy Bi ions, and that the off-center Ti displacement in the octahedra plays a minor role. Bond valence analysis shows that the underbonding of Bi with the adjacent oxide ions at the perovskite A site in high-temperature paraelectric state plays an essential role in the ferroelectric phase transition in the Bi4Ti3O12 system.
K. Katayama, K. Kato, T. Takenaka, M. Takata and K. Shinozaki
Y. Noguchi and M. Miyayama, "Ferroelectric Distortion in Bi4Ti3O12 Studied by Neutron Powder Diffraction", Key Engineering Materials, Vol. 350, pp. 65-68, 2007