Effect of the Matrix Subsystem on Piezoelectric Properties and Related Parameters of Lead-Free 1–3-Type Composites Based on Domain-Engineered Single Crystals

The effective piezoelectric coefficientsPiezoelectric coefficient and related energy-harvesting figures of meritFigure of merit of 1–0–3 and 1–2–2 composites2–2 composite are studied. In these compositesComposite the main component is the lead-freeLead-free [001]-poled domain-engineered [Lix(K1-yNay)1-x](Nb1-zTaz)O3: Mn single crystal, where x = 0.06, y = 0.1 – 0.3, z = 0.07 – 0.17, and the level of Mn doping is 0.25 mol. %. The matrix represents either a 0–3 corundum ceramicCeramic/polymer compositeComposite in the 1–0–3 structure or a 2–2 laminar polymer compositeComposite in the 1–2–2 structure. An influence of the aforementioned heterogeneous matrix on the piezoelectric coefficientsPiezoelectric coefficient d3j* and g3j*, figures of merit d3j*g3j* and F3j*σ, and their anisotropy in the studied 1–3-type compositesComposite at volume fractions of the single-crystal component 0 < m ≤ 0.3 is analysed by taking into account an elastic anisotropy of the matrix. LargeFigure of merit figures of merit d33*g33* and F33*σ are accounted for by an influence of the large piezoelectric coefficientPiezoelectric coefficient g33 of the single-crystal component. The studied 1–3-type compositesComposite are characterised by large values of the longitudinal piezoelectric coefficientPiezoelectric coefficient g33*, figures ofFigure of merit merit d33*g33* and F33*σ, and by the large anisotropy of d3j* and F3j*σ, which are important for transducer, sensor and energy-harvesting applications.