The effect of firing conditions on phase formation, microstructure and dielectric properties of BNKTNb-LSb ceramics prepared via the combustion technique

Abstract

The fabrication of 0.99[Bi_0.5(Na_0.82K_0.18)_0.5Ti_0.995Nb_0.005O₃]-0.01LiSbO₃ ceramics (BNKTNb-LSb) prepared by the combustion technique was studied. A single perovskite phase of BNKTNb-LSb powder was observed by the powders calcined at 700 °C for 2 h, which was lower than the solid-state reaction technique ∼150 °C. The BNKTNb-LSb ceramics showed the coexistence of a rhombohedral and tetragonal phase at a low sintering temperature. Then, the phase formation changed from a tetragonal to a pseudocubic phase when sintered at higher temperatures. The grain morphology of the BNKTNb-LSb ceramics exhibited a rather square shape and the average grain size of the ceramics was increased with increased sintering temperatures. The density, linear shrinkage, ϵ_r and ϵ_max of the BNKTNb-LSb ceramics tended to increase with increasing sintering temperatures up to 1125 °C and then decreased. At 1125 °C, the highest density, shrinkage, ϵ_r and ϵ_max were about 5.82 g/cm³, 18.7%, 1625 and 4465, respectively. The dielectric behavior corresponded with the XRD, density and the microstructure results.

Keywords:

• BNKTNb-LSb
• phase formation
• microstructure
• dielectric properties
• combustion technique

Acknowledgements

The authors wish to thank the Department of Physics, Faculty of Science, Naresuan University, for supporting facilities. Thanks are also given to Dr Antony Harfield and Mr Don Hindle for their help in editing the manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was financially supported by the Higher Education Research Promotion and National Research University project of Thailand, Office of the Higher Education Commission.