Enhanced electrical and energy harvesting performances of lead-free BMT modified BNT piezoelectric ceramics

Lead-free (1-x) (Bi0.5Na0.5)TiO3-xBi(Mg0.5Ti0.5)O3 or (1-x)BNT-xBMT (x = 0–0.20) piezoelectric ceramics have been investigated for phase evolution, microstructure, dielectric, ferroelectric, piezoelectric, electric field-induced strain, energy storage density, energy harvesting, and magnetic properties. All compositions exhibited high density sintered ceramics (~ 6.13–6.30 g/cm3). With increasing modifier content, the crystal structure changed from rhombohedral to cubic phase. When BMT content was added, the grain size and Tm were found to increase. The x = 0.05 ceramic showed good piezoelectric (low-field d33 = 159 pC/N) and ferroelectric (Pr = 23.84 µC/cm2, Ec = 34.41 kV/cm) properties. The BMT additive also produced an improvement in electric field-induced strain, energy storage efficiency, and magnetic properties. The highest piezoelectric voltage constant (g33 = 26.29 × 10−3 Vm/N) and the off-resonance figure of merit (FoM) for energy harvesting (~ 4.18 pm2/N) were also obtained for the x = 0.05 ceramic, which was ~ 3.4 times (240%) as compared to the pure BNT ceramic. This suggested that the ceramic has a potential to be one of the promising lead-free piezoelectric candidates for further use in piezoelectric energy harvesting applications.