Role of coexisting tetragonal regions in the rhombohedral phase of Na_(0.5)Bi_(0.5)TiO_3-xat.%BaTiO_3 crystals on enhanced piezoelectric properties on approaching the morphotropic phase boundary

摘要

The ferroelectric domain and local structures of Na_(0.5)Bi_(0.5)TiO_3-xat.%BaTiO_3 (NBT-x%BT) crystals for x = 0, 4.5, and 5.5 have been investigated by transmission electron microscopy. The results show that the size of polar nano-regions was refined with increasing xat. %BT. The tetragonal phase volume fraction, as identified by in-phase octahedral tilting, was found to be increased with BT. The findings indicate that the large electric field induced strains in morphotropic phase boundary compositions of NBT-x%BT originate not only from polarization rotation but also polarization extension.