Dielectrics and Paraelectric-Ferroelectric Phase Transitions

Abstract

In the linear approximation the dielectric displacement D = E +4πP and the electric field E are connected by a second order tensor ε, the dielectric function, invariant under the point-group symmetry operation of the crystal. We shall assume for simplicity scalar ε and dielectric susceptibility χ (in P/E = χ and ε = 1 + 4πχ). The frequency dependence of the complex dielectric constant can be determined from the decay function g(t) describing the gradual decrease of D when the field is suddenly turned off: