The diffuse phase transition in potassium strontium niobate

Abstract

The diffuse, paraelectric/ferroelectric, phase transition of Potassium Strontium Niobate is discussed. It is found that the Curie point is strongly dependent on the K and Sr content. Several possible causes of the diffuse phase transition (DPT) are discussed. An empirical relationship describing the behaviour of the inverse dielectric constant in the transition region, is presented. A statistical analysis of the DPT is described in terms of microscopic composition variations within the crystal arising from non-stoichiometry. Plots of the polar dielectric constant and spontaneous polarization against temperature, derived from this model, compare well with the experimentally measured quantities.