Optimum Conditions for Fabrication High-Density KNN-LS-BF Ceramics by Combustion Method

Abstract

The 0.996(0.95K_0.5Na_0.5NbO₃-0.05LiSbO₃)-0.004BiFeO₃ (KNN-LS-BF) ceramics were prepared by the combustion method using glycine as a fuel. The raw materials were mixed and calcined at various calcination temperatures (650–750°C) with different dwell time (0.5–3 h). Then, the calcined powders were pressed and sintered at various temperatures (1000–1100°C) with 0.5–4 h dwell time. The highest % perovskite orthorhombic phase was found in powder calcined at 700°C for 1 h. For the sintered pellets, the orthorhombic structure was found in ceramic sintered at 1075°C for 2 h using heating and cooling rate of 10°C/min. The SEM photographs showed square or rectangular morphology. The average grain size increased with the increasing of soak time. The highest densisty (4.47 g/cm³), maximum dielectric constant (ϵ_r = 6180) and lowest dielectric loss (tanδ = 0.1) at T_c were obtained in the sample sintered at 1075°C for 3 h. The densest sample showed the P_r = 14.3 μC/cm³ and E_c = 20.68 kV/cm at 40 kV/cm.

Keywords:

• KNN-LS-BF ceramics
• dielectric constant
• combustion method

Acknowledgments

This work was financially supported by the Thailand Research Fund (TRF). Thanks also to Department of Physics, Faculty of Science, Naresuan University for supporting facilities. Acknowledgments to Prof. Galina Popovici, for helpful comments and corrections of the manuscript.