The Influence of Nd³⁺ Addition on Crystallization, Microstructure and Dielectric Properties of 21K₂O-16Nb₂O₅-5Al₂O₃-58SiO₂ Glass Ceramics

Abstract

The ferroelectric glass-ceramics, with compositions of 21K₂O−16Nb₂O₅₋5Al₂O₃₋ 58SiO₂ (%mol)+ xNd₂O₃ where x = 0–3 mol%, were prepared via the melt-quenching technique and then isothermally heat-treated for the temperature ranges of 675–830°C and 1050°C. The phase formation, microstructural arrangements and dielectric properties were investigated as a function of dopant content. The XRD results showed that the glass-ceramics heat treated at lower temperatures contained 2 phases, K₃NbO₄ and KNb₃O₈. The line width of the diffracted peaks also revealed that the sizes of the precipitated crystals were on the nano-scale and this was confirmed by the SEM micrographs. Variation of the dielectric constant versus measured temperature revealed two successive phase transitions at approximately 275°C and above 400°C which matches the transition of the K₃NbO₄. The present results have demonstrated that appropriate heat treatment conditions can be employed to control crystallization and adjust dielectric properties of the glass-ceramics.

Keywords:

• Ferroelectric glass-ceramics
• crystallization
• potassium niobate

Acknowledgments

The authors wish to give special thanks to the funding institute, Faculty of Science, Ubon Ratchathani University and Human Resource Development in Science Project (Science Achievement Scholarship of Thailand, SAST) Thailand.