Domain orientations and piezoelectric properties in novel 2–2-type composites with two single-crystal components

The present paper is concerned with the piezoelectric properties and related parameters of the 2–2-type parallel-connected composites wherein rotations of the main crystallographic axes in ferroelectric single crystal components are analyzed. The composite consists of layers of two types that are regularly arranged along the non-polar axis. The Type I layer is a single domain 0.63Pb(Mg_1/3Nb_2/3)O₃–0.37PbTiO₃ single crystal (either tetragonal in Composite I or orthorhombic in Composite II). The Type II layer is a Li₂B₄O₇ single crystal/polyethylene medium with 0–3 connectivity. The composite as a whole is characterized by 2–0–2 connectivity. The following parameters of the composite are studied by taking into account the polarization orientation effect in the Type I layer and the microgeometry of the composite in the Type II layer: piezoelectric coefficients (Formula presented.) and (Formula presented.) their hydrostatic analogs (Formula presented.) and (Formula presented.) hydrostatic squared figure of merit (Formula presented.) (Formula presented.) piezoelectric anisotropy factors (Formula presented.) / (Formula presented.) and (Formula presented.) / (Formula presented.) It is shown that large values of the studied piezoelectric coefficients, hydrostatic parameters and anisotropy factors make Composite II more preferable in comparison to Composite I for hydroacoustic, piezoelectric sensor and energy-harvesting applications.