PZT 薄膜の縦方向圧電係数の測定

概要

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The ferroelectric and piezoelectric properties of 2000 A thick chemical solution deposited Pb(Zr_xTi_<1-x>)O_3 (PZT) thin films were investigated. Several Zr/Ti ratios were studied : 30/70,50/50 and 65/35,which correspond to tetragonal, nearmorphotropic, and rhombohedral symmetries. In all samples, a {111}-texture is predominant. Longitudinal piezoelectric coefficients and their dc field dependence were measured using the contact AFM (Atomic Force Microscopy) method. The expected trend of a maximum piezoelectric coefficient at or near to the MPB (Morphotropic Phase Boundary) was not observed. The composition dependence was small, with the maximum d_<33> occurring in the tetragonal material. To explain the results, crystallographic texture and film thickness effects are suggested. Using a modified phenomenological approach, derived electrostrictive coefficients, and experimental data, d_<33> values were calculated. Qualitative agreement was observed between the measured and calculated coefficients. Justifications of modifications to the calculations are discussed.
2000-03-25