Orientation dependence of electrical properties of 0.96Na0.5Bi0.5TiO3-0.04BaTiO3 lead-free piezoelectric single crystal

In this paper, a single crystal of 0.96Na(0.5)Bi(0.5)TiO(3)-0.04BaTiO(3) with dimensions of I broken vertical bar 30x10 mm was grown by the top-seeded-solution growth method. X-ray powder diffraction results show that the as-grown crystal possesses the rhombohedral perovskite-type structure. The dielectric, piezoelectric and electrical conductivity properties were systematically investigated with a OE (c) 001 >, a OE (c) 110 > and a OE (c) 111 > oriented crystal samples. The room-temperature dielectric constants for the a OE (c) 001 >, a OE (c) 110 > and a OE (c) 111 > oriented crystal samples are found to be 650, 740 and 400 at 1 kHz. The (T (m), epsilon (m)) values of the dielectric temperature spectra are almost independent of the crystal orientations; they are (306A degrees C, 3718), (305A degrees C, 3613) and (307A degrees C, 3600) at 1 kHz for the a OE (c) 001 >, a OE (c) 110 > and a OE (c) 111 > oriented crystal. The optimum poling conditions were obtained by investigating the piezoelectric constants d (33) as a function of poling temperature and poling electric field. For the a OE (c) 001 > and a OE (c) 110 > crystal samples, the maximum d (33) values of 146 and 117 pC/N are obtained when a poling electric field of 3.5 kV/mm and a poling temperature of 80A degrees C were applied during the poling process. The as-grown 0.96Na(0.5)Bi(0.5)TiO(3)-0.04BaTiO(3) crystal possesses a relatively large dc electrical conductivity, especially at higher temperature, having a value of 1.98x10(-11) Omega(-1)a <...m(-1) and 3.95x10(-9) Omega(-1)a <...m(-1) at 25A degrees C and 150A degrees C for the a OE (c) 001 > oriented crystal sample.