Dielectric, piezoelectric and electrostrictive properties of antiferroelectric lead-zirconate thin films

Abstract

Dielectric, piezoelectric and electrostrictive properties of antiferroelectric lead zirconate thin films, elaborated by sol gel on alumina substrates, have been studied as a function of the driving field magnitude EAC. Measurement of the displacement shows that the strain for applied fields below the antiferroelectric-ferroelectric transition is relatively small and that its main contribution arises from the electrostrictive effect. At the same time, due to the presence of a residual ferroelectricity, the piezoelectric effect also contributes to the displacement. At higher fields, a large strain is visible which comes mainly from the antiferroelectric to ferroelectric phase transition, the electrostrictive contribution however still being present. Similar to what has been shown for ferroelectric materials, strain versus the square of polarization loops S(P2) of the studied antiferroelectric material, exhibit hysteresis character due to the 180∘ domain walls which contribute to polarization but not to strain. Simultaneous measurement of polarization and displacement enables the extraction of the electrostrictive coefficient and a value Q = 0.082 ± 0.009 m4 C−2 has been obtained. Subtraction of the pure electrostrictive contribution from the displacement curve allows evidencing that the piezoelectric activity coexists with the electrostrictive effect at low fields. Maximum values of the equivalent piezoelectric coefficients are respectively 93 ± 3 pm V−1 and 100 ± 3 pm V−1 for the positive and the negative parts of the curve for a driving field magnitude EAC = 700 kV cm−1.