Orientation effects and figures of merit in advanced 2–2-type composites based on [011]-poled domain-engineered single crystals

Abstract

The paper reports new results that compare the group of performance figures of merit of piezo-active 2–2-type composites based on [011]-poled domain-engineered (1 − x)Pb(Zn_1/3Nb_2/3)O₃–xPbTiO₃ single crystals, where the main crystallographic axes in the crystal layers are rotated to tailor effective electromechanical properties and related parameters. Examples of the orientation and volume-fraction dependences of the figures of merit are analysed for the first time for the system of 2–2 single crystal/polymer composites and 2–0–2 single crystal/corundum ceramic/polymer composites at x = 0.0475–0.09. The connections between the piezoelectric coefficients , energy-harvesting figures of merit and modified figures of merit (j = 1, 2 and 3) are highlighted during rotation of the main X and Y crystallographic axes around the Z axis of the crystal layers. A similar orientation behaviour of , and and their large anisotropy are studied at specific volume fractions of the single-crystal component and for a variety of microgeometric architectures of a corundum ceramic/polymer layer with 0–3 connectivity. Maxima of the longitudinal parameters , and at x = 0.0475–0.09 and constant volume fraction of the single-crystal component of the 2–2-type composites are observed in a relatively narrow orientation range. A new performance diagram is built to show regions of a large anisotropy of and in a 2–0–2 composite and, as a result of the large piezoelectric coefficients and figures of merit, the composites show significant potential in the field of piezoelectric energy-harvesting and sensor applications.