Ferroelectric phase transition and non linear properties of SbSI

Abstract The anomalous dynamical properties of SbSI are described by a non-linear two-mode model based on the interaction of polarisable sulfur ions with antimony ions. This yields a satisfactory explanation of the temperature dependence of the ferroelectric soft mode. It is suggested that photo-domain and deformation effects are related to solitary wave excitations of the same model.