Effective electromechanical moduli of ferroelectric ceramics with fiber textures

In this letter, we report the predictions on the effective piezoelectric coefficients and electromechanical coupling factors of ferroelectric ceramics BaTiO3 and Pb(Mg1∕3Nb2∕3)O3–PbTiO3 (PMN-PT) with various fiber textures, including [001], [011], and [111], using a two-scale micromechanical model that accounts for microstructural phenomena at both domain and grain levels. It was observed that for BaTiO3 the [011] texture is optimal with highest d31 and d33, while for PMN-PT [001] texture is optimal despite the fact that [011]-oriented single-crystalline PMN-PT has higher d32 than that of [001]-oriented PMN-PT single crystal. In fact, [011]-textured PMN-PT ceramics have much smaller piezoelectric coefficients d32 and d33 than does [011]-oriented PMN-PT single crystal. It is also noted that [001]-textured BaTiO3 and PMN-PT ceramics have even higher electromechanical coupling factor k31 than that of [001]-oriented single crystals.