Effect of Calcination Temperature and Content of x and y on Crystal Structure and Microstructure of (1-x-y)Bi_0.5Na_0.5TiO₃–xBi_0.5K_0.5TiO₃–yBiFeO₃ Powders near MPB Prepared via the Combustion Technique

Abstract

(1-x-y)Bi_0.5Na_0.5TiO₃–xBi_0.5K_0.5TiO₃–yBiFeO₃ (abbreviated as BNKFT-x/y with 0.12 ≤ x ≤ 0.24, 0 ≤ y ≤ 0.07) lead-free piezoelectric powders were prepared by the combustion technique under various calcinations temperatures (600–800°C) for 2 h. The effect of calcination temperature and amounts of x and y on the crystal structure and microstructure were examined. The powders of all samples were well-calcined at 750 C°. The results indicated that there was an increase in the x and y concentrations of the crystalline structure and microstructure. XRD results of the BNKFT-x/0.03 and BNKFT-0.18/y ceramics with 0.12 ≤ x ≤ 0.24 and 0 ≤ y ≤ 0.07 showed the pure perovskite phase with a rhombohedral structure. The lattice parameter a increased from 3.8517 Å to 3.8696 Å and 3.8550 Å to 3.8623 Å with increasing x and y content, respectively. The SEM and TEM results indicated that the addition of y caused the particles to grow (from 291 nm to 308 nm) while the addition of x reduced particle growth (from 390 nm to 277 nm).

Keywords:

• (1-x-y)Bi_0.5Na_0.5TiO₃–xBi_0.5K_0.5TiO₃–yBiFeO₃
• combustion technique
• crystal structure
• microstructure

Acknowledgments

This work was financially supported by the Thailand Research Fund through the Royal Golden Jubilee Ph.D. Program (Grant no. PHD/0213/2552) to Miss Rattiphorn Sumang and Assist. Prof. Dr. Theerachai Bongkarn. The authors wish to thank the Naresuan University for supporting facilities. Thanks are given to Mr. Don Hindle for his help in editing the manuscript.