In this paper, we present a microscopic model for heterogeneous ferroelectric
and an order parameter for relaxor phase. We write a Landau theory based on
this model and its application to ferroelectric PbFe1/2βTa1/2βO3β
(PFT) and antiferroelectric NaNbO3β:Gd. We later discuss the coupling between
soft mode and domain walls, soft mode and quasi-local vibration and resulting
susceptibility function.Comment: 6 pages, Fundamental physics of ferroelectrics 200