Electrocaloric effect as a cause of dielectric loss

The difference between adiabatic and isothermal susceptibilities is caused by electrocaloric effect. Here we show how this effect contributes to diele ctric dispersion in a sample of finite dimensions or in a non-homogeneous m aterial. Maximum contribution to dielectric losses occurs at a frequency th at is inversely proportional to the square of characteristic dimension. The first Fourier components of susceptibility in a non-pyroelectric material are proportional to the square of the amplitude of ac field. In a pyroelect ric material with temperature dependent susceptibility a contribution to st atic polarisation arises due to alternating electric field. (C) 2001 Elsevi er Science Ltd. All rights reserved.