Dielectric and ferroelectric properties of Ba0.97-xCaxLa0.03Ti0.9Sn0.1O3 lead-free ceramics

The Ba0.97-xCaxLa0.03Ti0.90Sn0.10O3 (x = 0.02-0.10) lead-free piezoelectric ceramics were fabricated via conventional solid-state sintering process at 1480 °C. The effects of Ca2+ ions substitution on microstructure and electrical properties of the ceramics were researched. Ca2+ ions substitute for A-site Ba2+ ions to enter the unit cell maintaining the perovskite structure of th solid solution and the orthorhombic phase and tetragonal phase coexist in the composition with x = 0.04 to 0.10. SEM images confirmed the inhibiting effect of Ca ions on the grain growth process of the Ba0.97-xCaxLa0.03Ti0.90Sn0.10O3 ceramics. Uniformly distributed microstructures with high relative densities above 94.71% were developed with the further addition of Ca2+ ions. Main piezoelectric parameters were optimized at x = 0.04 with a high piezoelectric coefficient (d33 = 541 pC/N), a planar electromechanical coupling factor (kp = 45.7%), The analysis on the temperature dependence of dielectric permittivity approved the existence of the mixed ferroelectric-relaxor features in all the BCLST samples. The remnant polarization (Pr) reaches an extreme value of 7.81 μC/cm2 at x = 0.08.