Fabrication of 0.94NBT–0.06BT textured ceramics using plate-like NBT templates and their electrical properties

Abstract

The effect of crystallographic texture on the properties of 0.94(Na0.5Bi0.5TiO3)–0.06BaTiO3 (0.94NBT–0.06BT) ceramics were investigated in this study. The optimized rectangular plate-like Na0.5Bi0.5TiO3 (NBT) templates synthesized by a three-step molten salt method were used for the texturing. Dimensions of the major surfaces of the templates which were parallel to the (001) planes were measured as 8.4 µm × 10 µm (length × width) and 1 µm thickness on the average. The green textured ceramics were fabricated by tape casting method and then sintered. All ceramics were crystallized in pure perovskite structure and the degree of grain orientation was calculated as f = 91%. Brick wall-like microstructure for the textured NBT–BT ceramics with average grain size of ~ 12 µm was obtained by scanning electron microscopy. Depolarization temperature (Td) and temperature of maximum (Tm) of the dielectric permittivity were determined as 119 °C and 341 °C at 10 kHz for the textured ceramic, respectively. The value of maximum dielectric permittivity of textured ceramics was measured as εrmax ~ 5409 at 10 kHz. The high field (@50 kV/cm) piezoelectric d33* value was increased from 239 to 412 pm/V by texturing of the 0.94NBT–0.06BT ceramics. NBT template addition and texture development led to a decrease in AC conductivity.