High-entropy B-site doping enhances piezoelectricity and thermal stability in BNT-BT ceramics

Lead-free BNT-BT piezoelectric ceramics present excellent piezoelectric properties and are non-toxic, positioning them as one of the most promising lead-free ceramic systems for industrial applications. However, the typically issue is a low depolarization temperature ( T d ). Moreover, an increase in T d is accompanied by a reduction in the piezoelectric coefficient ( d 33 ), which severely hinders the improvement of piezoelectric performance and restricts applications at high temperatures. Accordingly, (Zn 0.2 Zr 0.2 Fe 0.2 Mo 0.2 Sb 0.2 )O 2 is doped into 0.935Bi 0.5 Na 0.5 TiO 3 -0.065BaTiO 3 with the morphotropic phase boundary (MPB) through the high-entropy doping strategy in this study, to design the system of 0.935Bi 0.5 Na 0.5 (Zn 0.2 Zr 0.2 Fe 0.2 Mo 0.2 Sb 0.2 ) x Ti (1-x) O 3 -0.065BaTiO 3 . High-entropy doping at the B-site induces lattice distortion and increases defect density, thereby generating domain-wall pinning and ultimately enabling the synergistic enhancement of T d and d 33 . Notably, at x = 0.1%, d 33 reaches 200 pC/N and T d increases to 108 °C, achieving simultaneous optimization of piezoelectric performance and temperature stability. These results indicate that high-entropy doping effectively addresses the issue of simultaneous optimization encountered in conventional doping, thereby providing a novel strategy to achieve synergistic optimization of T d and d 33 .