摘要
In this work,the effects of rare earth(RE)dopants on the phase structure,microstructure,and electrical properties of lead-free bismuth sodium titanate(BNT)-based ceramics were studied.Rare earth elements(i.e.,Sm,Gd,Ho,Pr,Y,and Yb)were selected as the dopants to replace the Bi site of Bi_(0.5)(Na_(0.8)K_(0.2))0.5TiO_(3) ceramics.It was found that the addition of moderate RE ions reduced the temperature of ferroelectricrelaxor transition(T_(f-r))and the dielectric maximum at lower temperature,while the slight influence on the dielectric maximum at higher temperature and microstructure were observed.Hereby,the threestage evolution of phase structure after introducing RE ions was confirmed.A high piezoelectric coefficient d_(33) of ~190 pC/N was achieved due to the improved dielectric constant in the state with stable electric field-induced ferroelectric phase.The high strain property and converse piezoelectric coefficient d_(33)* of ~340 pm/V were obtained in the state with the coexistence of nonergodic and ergodic relaxor phases when T_(f-r) approached room temperature.The degenerated overall electromechanical properties exhibited in the state with complete ergodic relaxor phase.This study affords a significant guidance for optimizing the piezoelectricity of BNT-based ceramics utilizing rare earth dopants.
基金
the support of the National Natural Science Foundation of China(51972215).
