Ferroelectrics UK 2001 PDF

ABSTRACT

Thin film capacitor structures, containing the lead-based relaxor Pb(Mgl/3Nb2 /3)03 (PMN) as the dielectric layer, were made by pulsed-laser deposition on both MgO and LaAI03 substrates. The dielectric constant of the relaxor was found to be considerably lower than in bulk, while the temperature of the dielectric maximum (Tm) was only slightly depressed, irrespective of the expected in-plane strain induced by the substrate (compressive for LaAI03 and tensile for MgO). The frequency dependence of Tm was also seen to be more pronounced in thin films than in bulk.

A rationalisation of these differences is presented by consideration of mismatch strain between substrate and film in the context of a semi-empirical modified Landau-GinzburgDevonshire model. The predictions of the model are also compared with available experimental results from the literature.

Edited by: I.M. Reaney, D.C. Sinclair