Point defect engineering of high temperature piezoelectric BiScO3-PbTiO3 for high power operation

BiScO3-PbTiO3 is used as a model system of BiMO3-PbTiO3 perovskite solid solutions with enhanced electromechanical response at ferroelectric morphotropic phase boundaries, and high Curie temperature to demonstrate specific point defect engineering for high power operation. The objective is to obtain a range of piezoelectric ceramics comparable to hard Pb(Zr,Ti)O3 materials, optimized for the different applications. In this work, a comprehensive study of Mn substitution for Sc is provided. Care is taken to isolate the effects of the point defects from those of concomitant structural and microstructural changes that have been previously described after MnO2 addition. Results strongly suggest that Mn substitution results in the formation of (MnSc′-VO) dipolar complexes that effectively clamp domain walls. This is the same mechanism responsible of hardening in Pb(Zr,Ti)O3. Indeed, Bi0.36Pb0.64Sc0.36-x MnxTi0.64O3 with x = 0.02 is shown to be a high sensitivity piezoelectric with strongly reduced losses, suitable for high power operation between 200 and 400 °C.