CRYSTAL ORIENTATION DEPENDENCE OF PIEZOELECTRIC PROPERTIES OF LEAD-ZIRCONATE-TITANATE NEAR THE MORPHOTROPIC PHASE-BOUNDARY

The piezoelectric and dielectric constants in different crystal orient ations of the lead zirconate titanate (PZT) have been phenomenological ly calculated for the compositions near the morphotropic phase boundar y at room temperature. For a tetragonal PZT, the effective piezoelectr ic constant d(33) monotonously decreases as the crystal cutting angle from the spontaneous polarization direction [001] increases. However, for a rhombohedral PZT, the effective piezoelectric constant d(33[001] //) along the perovskite [001] direction was found to be, much larger than those along the spontaneous polarization direction [111]. This cr yst;ll orientation-related enhancement is emphasized as the compositio n approaches the morphotropic phase boundary. This suggests that by ad opting the perovskite [001] orientation with a rhombohedral compositio n near the morphotropic phase boundary, the piezoelectric constant d(3 3) for PZT can be greatly enhanced. (C) 1998 American Institute of Phy sics. [S0003-6951(98)03619-5].