“Dirty” Displacive Ferroelectrics

It appears that the lattice dynamic theory of displacive ferroelectrics does not predict correctly the zero frequency clamped value of the dielectric constant. This effect is particularly evident in disordered crystals. We qualitatively show, using a very simple model, that the contribution to the dielectric constant of a localized impurity can be enhanced considerably when it is coupled to a lattice mode. © 1974, Taylor & Francis Group, LLC. All rights reserved.