The Effects of Annealing Process on Dielectric and Piezoelectric Properties of BMT-Base Lead-Free Ceramics

By using nitric acid as the fuel, the lead-free ceramic of Ba(Ti1-x,Mgx)O3 (x = 0.31) was prepared by auto combustion method (ACM). To make a comparison, this ceramic was also prepared using mixed oxide method (MOM). By X-ray diffraction, the phase structures of two samples were studied, and the results showed that rising temperatures would reduce unwanted phases. The piezoelectric and electrical properties as a function of calcination and sintering temperatures were investigated. The results showed that the outstanding electrical properties were obtained for nanoceramic with this composition. The SEM image of the grain size was estimated around 2 micrometers, and the grain size increased with the increasing of sintering temperature for two samples. The curie temperature of the BMT-ACM was 126°C and it’s significantly larger than the curie temperature of BMT-MOM which was 118°C. The results of electrical properties emphasized that the synthesis optimum temperature for two samples was about 1200°C and it was the best temperature that led to improved properties such as dielectric constant, polarization and piezoelectric coefficients.