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 dielectric dispersion in a sample of finite dimensions or in a non-homogeneous material. Maximum contribution to dielectric losses occurs at a frequency that 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 pyroelectric material with temperature dependent susceptibility a contribution to static polarisation arises due to alternating electric field. (C) 2001 Elsevier Science Ltd. All rights reserved.