Thermally stable electrostrain in BiFeO_3-BaTiO_3-based high temperature lead-free piezoceramics

摘要

BiFeO3-BaTiO3 ceramics possess both high electromechanical properties and a high Curie temperature, which are promising high temperature lead-free piezoactuator materials. However, the poor thermal stability of electrostrain limits their practical exploration. Here, we report a temperature stable electrostrain of 0.18% at 6kV/mm, with a variation of 13% from 25 degrees C to 175 degrees C for (1-x)(0.67BiFeO(3)-0.33BaTiO(3))-xSr(0.8)Bi(0.1)?0.1TiO2.95 solid solutions with x=0.04. The addition of a relaxor ferroelectric Sr0.8Bi0.1?0.1TiO2.95 (SBT) breaks the long range ferroelectric order of BiFeO3-BaTiO3 (BFBT) ceramics. More importantly, the combined effect of the negative temperature dependent electrostrain for relaxors and the positive one for the parent BFBT contributes to the superior temperature stability of the electrostrain. This work provides an effective method for designing piezoelectric materials with an enhanced temperature stability for high temperature actuator applications.