Structural study of phase transitions in the dsp-type ferroelectrics

Abstract

Ferroelectric phase transition in DSP-type compounds is reviewed from a structural point of view. Contrary to the pronounced disordered nature of the methyl groups, the ionic atoms which bear the major part of spontaneous polarization display no disordering at all. It is concluded that the ionic atoms are weakly correlated with the disordered methyl groups. We show that the conclusion is in accordance with a special atomic arrangement of the DSP-type structure.