Effect of sintering temperature of NBT–6BT lead-free ceramics on the structural, ferroelectric and piezoelectric properties

The lead-free \(\left( {{\text{Na}}_{0.5} {\text{Bi}}_{0.5} } \right)_{0.94} {\text{Ba}}_{0.06} {\text{TiO}}_{3}\) (NBT–6BT) ceramics was fabricated at various sintering temperatures using a conventional solid-state reaction method. The effect of calcination temperature was systematically investigated on the structural properties. The XRD results show that the 850 °C is the best calcination temperature, where the NBT–6BT ceramic had the largest crystallite size with a dense sample, 96% of the theoretical value. However, the density decreased significantly with increasing the calcination temperature above 850 °C due to the secondary phase formation. On the other hand, the effect of sintering temperature was studied on the piezoelectric and ferroelectric properties evolutions. It is found that the optimal ferroelectric and piezoelectric values were obtained at 1150 °C (Pr = 27 µC/cm2, Ec = 3.89 kV/mm and d33 = 110 pC/N). According to these results, we suggest that 850 °C and 1150 °C can be considered as optimal calcination and sintering temperature in NBT–6BT ceramic, respectively.