Influence of imperfect surface layers on dielectric and pyroelectric properties of ferroelectric thin film

Using the Ginzburg–Laudau–Devonshire theory and taking into account structural difference between imperfect surface layers and bulk ferroelectrics, the dielectric and pyroelectric properties of ferroelectric thin films coated with two metallic electrodes have been studied. The numerical results show that the effects of imperfect surface layers are to increase the effective dielectric susceptibility at room temperature through lowering the phase transition temperature. Both the dielectric susceptibility peak and pyroelectric coefficient peak shift to lower temperatures due to the contribution of the imperfect surface layers. The incompletely screened non-uniform depolarization field makes the susceptibility distribution more uniform. r 2005 Elsevier B.V. All rights reserved. PACS: 77.80.Bh; 77.55.+f; 77.80.Dj