Piezoelectric properties of PbTiO₃-based 0–3 and 0–1–3 composites

The effective piezoelectric coefficients of novel 0–3 'relaxor-ferroelectric Pb(A 1/3 B 2/3 )O 3 –PbTiO 3 -type single-crystal–ferroelectric PbTiO 3 -based ceramic' and 0–1–3 'relaxor-ferroelectric Pb(A 1/3 B 2/3 )O 3 –PbTiO 3 -type single-crystal–ferroelectric PbTiO 3 -based ceramic–polymer' composites are determined at various volume concentrations of piezo-active components. The role of the piezo-active single-crystalline and ceramic components in the non-monotonic concentration dependence of the piezoelectric properties of these composites is analysed. First, some empirical relationships among electromechanical constants of the components are given and discussed, which guarantee considerably high values of the hydrostatic piezoelectric coefficients and of the above-mentioned 0–3 composites with spheroidal inclusions. Next, it is shown that the presence of the relaxor-ferroelectric component in the 0–1–3 composite results in an unusual concentration behaviour of its piezoelectric coefficients and , which has not been described before in papers on the well-studied 1–3 'ferroelectric ceramic – polymer' composite. Examples of the large piezoelectric anisotropy of the 0–1–3 composite (i.e. conditions , , and , where are electromechanical coupling factors) are also considered and discussed.