2–2 composites based on [011]-poled relaxor-ferroelectric single crystals

C. R. Bowen, D. N. Betts, H. A. Kim, V. Yu. Topolov

OAI: oai:purehost.bath.ac.uk:openaire_cris_publications/7d95e5d4-77af-4ec3-b46e-75338054e1a9 • DOI: https://doi.org/10.1007/s00542-013-2012-8

In this paper we explore the effect of the orientation of the main crystallographic axes in relaxor-ferroelectric single crystals (SCs) on the piezoelectric anisotropy and squared figures of merit of 2-2 parallel-connected SC/auxetic polymer composites. The single-crystal component for the composite is chosen from the perovskite-type solid solutions with compositions near the morphotropic phase boundary and poled along the perovskite unit-cell [011] direction (mm 2 symmetry of domain-engineered SCs). The orientation of the main crystallographic axes in the single-crystal component is observed to strongly influence the piezoelectric coefficients d3j* squared figures of merit d3j* g3j* electromechanical coupling factors k3j* and hydrostatic analogs of these parameters of the 2-2 composite. Inequalities | d33*/ d 3f*| > 5 and | k33*/ k3f*| > 5 (f = 1 and 2) are achieved at specific orientations of the main crystallographic axes due to the significant anisotropy of the elastic and piezoelectric properties of the single-crystal component. The use of an auxetic polyethylene (a polymer component with a negative Poisson's ratio) leads to a significant increase in the hydrostatic parameters. Particular advantages of such composites over conventional ceramic/polymer composites are taken into account for transducer, hydroacoustic, energy harvesting, and other applications.