Composition‐induced phase transitions and enhanced electrical properties in bismuth sodium titanate ceramics

Here, the composition‐induced phase transition and enhanced electrical properties were investigated in terms of lead‐free {[Bi 0.5 (Na 0.82− x K 0.18 Li x ) 0.5 ] 1− y Sr y }TiO 3 ( BNKLST ‐ x / y, x =0‐0.175 and y =0‐0.125) ceramics. The rhombohedral and tetragonal phase boundary can be constructed, and then the enhancement of piezoelectric properties ( d 33 ~271 pC/N and k p ~0.38) can be observed for x =0.10 and y =0.05, which is superior to most reported results in polycrystalline BNT ‐based ceramics. In particular, a fatigue‐free behavior after 10 6 polarization switching cycles was shown in the BNKLST ‐0.10/0.05 ceramics due to the reversible field‐induced phase transition, and a slight decrease in d 33 (~4.5%) was also shown. More importantly, the general model of electric field, temperature, and composition‐induced phase transition was employed to explain the enhancement of piezoelectric and fatigue properties. We believe that the composition design of this system can promote the development of bismuth sodium titanate lead‐free ceramics.