Dielectric and piezoelectric properties of La{sub}2O{sub}3 doped (Bi{sub}0.5Na{sub}0.5){sub}0.92(Ba{sub}0.8Sr{sub}0.2){sub}0.08 TiO{sub}3 lead-free piezoelectric ceramics

摘要

Lead-free piezoelectric ceramics (Bi{sub}0.5Na{sub}0.5){sub}0.92 (Ba{sub}0.8Sr{sub}0.2){sub}0.08 TiO{sub}3+x mol% La{sub}2O{sub}3(x=0, 0.1, 0.3, 0.5, 0.8) were synthesized by conventional solid state reaction. The crystal structure of all compositions is mono-perovskite ascertained by XRD. The grain size decreased and diffuse phase transition behavior was more evident with the increasing amount of La{sub}2O{sub}3. The piezoelectric constant d{sub}33 and the electromechanical coupling factor k{sub}p showed the maximum value of 165 pC/N and 0.322 at 0.3% and 0.1% La{sub}2O{sub}3 addition, respectively, and rapidly decreased when La{sub}2O{sub}3 addition over 0.5%. The loss tangent tanδlinearly increased and the mechanical quality factor Q{sub}m linearly decreased with the increasing amount of La{sub}2O{sub}3.