Firing temperatures effect on phase formation, microstructure and electrical properties of BNKLT-Sm ceramics
Metarsit Klinbanmor(a), Pamornnarumol Bhupaijit(a), Theerachai Bongkarn(a,b*),
a) Department of Physics, Faculty of Science, Naresuan University, Phitsanulok, 65000, Thailand
b) Research Center for Academic Excellence in Applied Physics, Faculty of Science, Naresuan University, Phitsanulok, 65000, Thailand
*researchcmu[at]yahoo.com
Abstract
Lead-free Bi0.5(Na0.68K0.22Li0.10)0.5TiO3 + 0.003mol Sm2O3 (BNKLT-Sm) ceramics were synthesized via solid-state combustion techniques with calcination of 750–850°C and sintering temperature between 1025 and 1100°C for 2 h. The results showed that increasing the calcination temperature, the percent perovskite phase and particle size of the BNKLT-Sm powders were increased. The BNKLT-Sm powder calcined at 800°C provided the best condition without inducing any impurity phase. For the sintered ceramics, the influence of the sintering temperature on phase formation, microstructure and electrical properties was investigated. All samples sintered at different temperatures possessed a coexisting phase between rhombohedral (R) phase and tetragonal (T) phase and the R phase became dominant when sintering temperature increased. The microstructure of all ceramics showed a rectangular shape and anisotropic growth. The average grain size increased with increasing of sintering temperature. Dielectric and ferroelectric behavior displayed relaxor characteristics in all samples. The maximum dielectric constant at Tm (m) of 4777 and the high remnant polarization (Pr) of 5.03 µC/cm2 were obtained by the densest ceramics (5.85 g/cm3), which sintered at 1075°C.
Keywords: BNKLT-Sm; solid-state combustion; dielectric; ferroelectric
Topic: Metal alloys, ceramics and composite materials