Firing Temperatures Effect on Phase Formation, Microstructure and Electrical Properties of BNBKL Ceramics Fabricated via the Solid-State Combustion Technique

Abstract

Lead-free 0.85Bi_0.5Na_0.475Li_0.025TiO₃-0.11Bi_0.5K_0.5TiO₃-0.04BaTiO₃ (BNBKL) ceramics were prepared by the solid-state combustion technique. The BNBKL powders and ceramics were calcined and sintered between 650 to 850 °C for 1–5 h and 1100 to 1140 °C for 2 h, respectively. The effect of firing temperatures on the phase structure, microstructure, and electrical properties of BNBKL ceramics was investigated. X-ray diffraction patterns of BNBKL powders showed a pure perovskite phase structure at a calcination temperature of 800 °C for 3 h. The BNBKL ceramics sintered at different temperatures possessed coexisting rhombohedral (R) and tetragonal (T) phases. The ceramic grains showed a polyhedral shape with directionless growth. The average grain size of the BNBKL ceramics increased from 0.80 to 1.26 µm when the sintering temperature increased from 1100 to 1140 °C. The density of the BNBKL ceramics increased as the sintering temperature increased up to 1120 °C, after that it decreased. The highest density (6.05 g/cm³) and dielectric constant (5855), were obtained at the sintering temperature of 1120 °C. As the sintering temperature increased, the polarization hysteresis loops (P-E loops) of the BNBKL ceramics exhibited less saturation and were more pinched, indicating more relaxor behavior.

Keywords:

• BNBKL
• solid-state combustion
• dielectric and ferroelectric

Acknowledgments

The authors thank the Department of Physics, Faculty of Science, Naresuan University for their supporting facilities. Thanks are also given to Asst. Prof. Dr. Kyle V. Lopin for his help in editing the manuscript.

Disclosure Statement

No potential conflict of interest was reported by the author(s).