Crystallographically engineered BaTiO3 single crystals for high-performance piezoelectrics

Dielectric and piezoelectric properties of BaTiO3 single crystals polarized along the < 001 > crystallographic axes were investigated as a function of temperature and dc bias. Electromechanical coupling (k(33))similar to 85% and piezoelectric coefficients (d(33))similar to 500 pC/N, better or comparable to those of lead-based Pb(Zr, Ti)O-3 (PZT), were found from < 001 >-oriented orthorhombic crystals at 0 degrees C, as a result of crystallographic engineering. A rhombohedral BaTiO3 crystal polarized along < 001 > also exhibited enhanced piezoelectric performance, i.e., k(33)similar to 79% and d(33)similar to 400 pC/N at -90 degrees C, superior to PZTs at the same temperature. It was found that the crystal structure determined the (in)stability of the engineered domain state in BaTiO3 single crystals. Rhombohedral (3m) crystals at -100 degrees C exhibited a stable domain configuration, whereas depoling occurred in crystals in the adjacent orthorhombic phase upon removal of the E field. (C) 1999 American Institute of Physics. [S0021-8979(99)04517-X].