Dielectric and piezoelectric properties of sol-gel derived lead magnesium niobium titanate films with different textures

The piezoelectric and dielectric constants for Pb(Mg1/3Nb2/3)O-3-PbTiO3 (PM N-PT, 70/30) films with different orientations were measured. PMN-PT films were deposited on Pt(111)-passivated silicon substrates using a modified so l-gel process. The room temperature dielectric constants K for the {100}-or iented films were 2500-2600, while K for {111}-oriented films were 1900-200 0. In both cases tan delta was less than 0.03. The dependence of the piezoe lectric coefficient d(31) of the PMN-PT films on the poling fields was inve stigated. The d(31) coefficients of {100}-oriented PMN-PT films were found to range from -28 to -69 pC/N with poling field. The {100}-oriented PMN-PT films showed larger piezoelectric coefficient than {111}-oriented films. Th e d(33) coefficients of the 1.5 mum thick {100} oriented PMN-PT films were similar to 170-183 pC/N. The aging rate of -d(31) was similar to4%-10%/deca de. (C) 2001 American Institute of Physics.