Growth and electrical properties of Na0.5Bi0.5TiO3-K0.5Bi0.5TiO3 lead-free single crystals by the TSSG method

A series of NBT-KBT lead-free crystals with dimensions of Phi 35 x 10 mm were successfully grown by the TSSG method. The as-grown crystals possess rhombohedral perovskite structure at room temperature. The curves epsilon(T) for all crystals show two abnormal dielectric peaks. The depolarization temperatures T-d derived from the first peak of curves tan delta(T) vary with the KBT content, which are 130, 150, 140, and 115 degrees C respectively, for (100 - x)NBT - xKBT (x=5, 8, 12, 15) crystals, being well consistent with the T-d obtained from the temperature dependence of k(t). A notable thermal hysteresis, Delta T approximate to 35 degrees C, for ferroelectric-antiferroelectric phase transition was also disclosed for 92NBT-8KBT crystal. The investigation of orientation dependence for electrical properties disclosed the dielectric parameters show weak anisotropy. The piezoelectric constants (d(33)) are 147, 175, 205, 238 pC/N and the values of k(t) are 38%, 52%, 52%, 54%, respectively for (100-x)NBT-xKBT (x=5, 8, 12, 15) crystals. (C) 2016 Elsevier Ltd and Techna Group S.r.l. All rights reserved.