Compositional dependence of Pb(Mg1/3,Nb2/3)O3–PbTiO3 piezoelectric thin films by combinatorial sputtering

Abstract

We evaluated the compositional dependence of Pb(Mg1/3,Nb2/3)O3–PbTiO3 (PMN–PT) polycrystalline thin films by combinatorial sputtering. We prepared compositional gradient (1 − x)PMN–xPT polycrystalline thin films with preferential orientation along the 〈001〉 direction in the composition range of x = 0–0.62. We determined that the morphotropic phase boundary (MPB) composition of PMN–PT polycrystalline thin film existed at around x = 0.35, from the X-ray diffraction (XRD) measurements. The maximum value of relative dielectric constants (εr = 1498) was obtained at approximately x = 0.23. On the other hand, the piezoelectric coefficients (|e31,f| = 14.1 C/m2) peaked at the determined MPB composition of x = 0.35. From the results of the compositional dependence of dielectric and piezoelectric characteristics, the FOM () of the PMN–PT (x = 0.35) thin film reached 21 GPa, which is much higher than that of the other polycrystalline piezoelectric thin films. These results suggest that PMN–PT (x = 0.35) thin film is a promising material for high-efficiency piezoelectric MEMS energy harvesters.