Characterization of Piezoelectric Property of Sol-Gel PZT Thin Films and Its Improvement by Poling

Abstract

A method for evaluating transverse piezoelectric coefficient of a thin film on a bulk substrate has been proposed. The measurement method is simple and independent on elastic constants of both the film and the substrate when the film is thinner enough than the substrate. Piezoelectric properties of sol-gel derived PZT (Pb(Zr, Ti)O₃) thin films before and after electrical poling were evaluated using this method. The piezoelectric coefficient h₃₁ of the film of 2.2μ thickness is -400MV/m after a poling of -200kV/cm, which is about a half of that of poled ceramic. Improvement of piezoelectric property by poling was confirmed to be caused by increase of retained polarization with clear proportionality.