Relationships between piezoelectric and energy-harvesting characteristics of 1-2-2 composites based on domain-engineered single crystals

The paper reports on the piezoelectric performance, electromechanical coupling and related energy-harvesting figures of merit of three forms of 1-2-2 composites based on domain-engineered single crystals. The effect of the single-crystal piezoelectric properties and elastic properties of the laminar polymer matrix on the appropriate figures of merit of the composite is studied. The main active components of the studied composites are [0 0 1]-poled perovskite-type single crystals with chemical compositions: 0.92Pb(Zn1/3Nb2/3)O-3-0.08PbTiO(3), 0.67Pb(Mg1/3Nb2/3)O-3-0.33PbTiO(3) and [Li (x) (K1- (y) Na (y) )(1-) (x) ](Nb1- (z) Ta (z) )O-3: Mn, where x = 0.06, y = 0.1-0.3, z = 0.07-0.17, and the level of Mn doping is 0.25 mol. %. Examples of non-monotonic volume-fraction dependences of the piezoelectric properties, figures of merit and anisotropy factors are analysed. New diagrams are first built to demonstrate the volume-fraction regions where a large anisotropy of the piezoelectric coefficients d (3) (j) * and electromechanical coupling factors k (3) (j) * is achieved, and where energy-harvesting figures of merit of the composite are at least five times larger than analogous parameters of single-crystal components. The studied 1-2-2 composites are of interest as anisotropic materials with high piezoelectric sensitivity and large figures of merit which are important for sensor, energy-harvesting and related applications.