The Soft Mode Phase Transition in Bi2Ti4O11

1 Introduction In 1962, Subbarao’s thermal expansion and the dielectric measurement indicated a phase transition occurring at 250℃ in Bi2Ti4O11. The conclusion was firstly confirmed by Raman experiment at high temperature. The phase transition is connected with the softening of the mode with temperature. In our previous study, we reported its Raman spectra under high pressure. The experimental results reveal that a pressure-induced phase transition occurs at 3.7 GPa. It has also been found that the intensity, half-width, phase