Growth and electrical properties of 0.95Na0.5Bi0.5TiO3–0.05K0.5Bi0.5TiO3 lead-free piezoelectric crystal by the TSSG method

0.95Na0.5Bi0.5TiO3–0.05K0.5Bi0.5TiO3 lead-free piezoelectric single crystal with rhombohedral structure was grown by the top-seeded solution growth method. The temperature dependence of dielectric constant and loss, polarization hysteresis loops, the optimum poling condition and the electromechanical coupling property were investigated for the 〈100〉-oriented as-grown crystal. The curves ε(T) show two anomalies, which are related to the two phase transformations at the temperature range of 130–340 °C. The piezoelectric constant d33 and electromechanical coupling coefficient kt for the 〈001〉-oriented crystal at room temperature reached 147 pC/N and 0.52, respectively. The value of kt demonstrated a relatively stable thermal electromechanical coupling property over the temperature range of 15–130 °C.

► High-quality and large-size 0.95NBT–0.05KBT crystal has been firstly grown.
► The phase transition related to the two abnormal dielectric peaks was elucidated.
► The temperature dependence of the value kt for the crystal was firstly reported.
► The optimum poling condition for the crystal was firstly investigated.