Piezoelectric Performance and Hydrostatic Parameters of Novel 2–2-Type Composites

This paper provides a detailed study of the structure - piezoelectric property relationships and the hydrostatic response of 2–2-type composites based on relaxor-ferroelectric 0.72Pb(Mg1/3Nb2/3)O3–0.28PbTiO3 single crystal material. Type I layers in the composite system are represented by a single-domain [111]-poled single crystal. Changes in the orientation of the crystallographic axes in the Type I layer are undertaken to determine the maximum values of the hydrostatic piezoelectric coefficients dh*, gh*, and eh*, and squared figure of merit dh* gh* of the composite. The Type II layers are a 0–3 composite whereby inclusions of modified PbTiO3 ceramic are distributed in a polymer matrix. A new effect is described for the first time due to the impact of anisotropic elastic properties of the Type II layers on the hydrostatic piezoelectric response that is coupled with the polarization orientation effect in the Type I layers. Large hydrostatic parameters gh*≈300–400 mV˙m/N, eh*≈40–45C/m2, and dh* gh*~ 10−11 Pa−1 are achieved in the composite based on the 0.72Pb(Mg1/3Nb2/3)O3–0.28PbTiO3 single crystal. Examples of the large piezoelectric anisotropy (| d33* / d3f* |≥5 or | g33* / g3f* |≥5) are discussed. The hydrostatic parameters of this novel composite system are compared to those of conventional 2–2 piezocomposites.