Piezoelectric instability in < 011 >-oriented Pb((B1/3B2/3II)-B-I)O-3-PbTiO3 crystals

Piezoelectric investigations of < 011 > -oriented Pb(Mg1/3Nb2/3)O-3-PbTiO3 (PMN-PT) and Pb(Zn1/3Nb2/3)O-3-PbTiO3 (PZN-PT) crystals have revealed high electromechanical properties. Piezoelectric constants of up to 5000-6000 pC /N and electromechanical coupling coefficients of up to 0.95 have been obse rved near the ferroelectric rhombohedral to ferroelectric tetragonal transf ormation. The data clearly demonstrate that the enhanced electromechanical performance of oriented piezocrystals is not constrained to the < 001 > ori entation. Furthermore, analysis of the data has demonstrated the presence o f piezoelectric instability between two ferroelectric states at a critical transformation temperature and/or electric field. (C) 2001 American Institu te of Physics.