Sintering Temperature Effect on the Structural Phase, Microstructure and Electrical Properties of 0.92BNKLT-0.08BST Ceramics Prepared via the Solid State Combustion Method

Abstract

Binary system ceramics of 0.92Bi_0.5(Na_0.68K_0.22Li_0.10)_0.5TiO₃-0.08Ba_0.5Sr_0.5TiO₃ (abbreviation as 0.92BNKLT-0.08BST) were prepared by the solid-state combustion method. Different sintering temperatures (between 1050 and 1150 °C for 2 h) were investigated for their effects on the structural phase, microstructure and electrical properties. 0.92BNKLT-0.08BST ceramics showed a pure perovskite structure with coexisting phases of rhombohedral and tetragonal, in all samples. The tetragonality and the lattice parameters increased with increasing sintering temperatures. The ceramics’ grains showed polygonal shapes with anisotropic growth. The average grain size increased from approximately 0.35 to 0.83 µm when the sintering temperature increased from 1050 to 1150 °C. The highest density of 5.83 g/cm³ and the maximum dielectric constant at T_m (ε_m) 5006 were obtained by the sample sintered at 1100 °C for 2 h. With higher sintering temperatures, the P-E hysteresis curves exhibited more pinched loops which indicated higher relaxor behavior. A large strain of 0.21% and a high normalized strain piezoelectric coefficient ($d_{33}^{*}$), around 420 pm/V, were achieved at the sintering temperature of 1125 °C for 2 h.

Keywords:

• BNKLT-BST
• solid-state combustion
• perovskite
• ferroelectric
• strain

Acknowledgments

The authors wish to thank the Department of Physics, Faculty of Science, Naresuan University for their supporting facilities. This work was supported by the National Science, Research and Innovation Fund (NSRF). Thanks are also given to Asst. Prof. Dr. Kyle V. Lopin for his help in editing the manuscript.