Structural studies of the ferroelectric phase transition in Bi4Ti3O12

A variable-temperature synchrotron X-ray diffraction study of the phase transitions in the ferroelectric n = 3 Aurivillius oxide Bi4Ti3O12 is described. At room temperature the structure of Bi4Ti3O12 is orthorhombic in space group B2eb and this continuously transforms to the high-temperature tetragonal I4/mmm structure via an intermediate orthorhombic phase. The possible space groups of this intermediate orthorhombic phase have been identified by using group theory.