ROLE OF Bi(Mg0.5Ti0.5)O3 DOPING AND ANNEALING PROCESS ON MECHANICAL, AND ELECTRICAL PERFORMANCES OF (Bi0.5Na0.5)TiO3 LEAD-FREE CERAMICS

Lead-free binary system of (1-x)(Bi0.5Na0.5)TiO3-xBi(Mg0.5Ti0.5)O3 ceramics referred to (1-x)BNT-xBMgT (x = 0-0.15) have been studied. The optimum sintering temperature was 1,150°C/4 h, corresponding to high relative density of 98.46-99.25%. All ceramics had a single perovskite structure. When increasing BMgT, the phase was a change to pseudo-cubic. The relative density and linear shrinkage increased with BMgT, which resulted to an improvement of dielectric and mechanical. The maximum dielectric at RT and mechanical (HV = 5.56 GPa, HK = 5.43 GPa, E = 94 GPa and KIC = 1.61 MPa.m1/2) were obtained for the x = 0.15. In addition, the x = 0.05 had the highest of kp (0.585) and low-field d33 (159 pC/N). Effects of annealing process on densification and dielectric were also studied in this work. After annealed at 1,000°C for 24 h, the x = 0.05 had the optimum dielectric improvement (emax = 3,440), and this value was 45.15% higher than that of the non-annealed sample (emax = 2,370). The observed results suggested that added-BMgT and annealing process can enhanced mechanical, dielectric, and piezoelectric performances of BNT ceramic.