Property of A/B Sites Substituted Bismuth Sodium Titanate Based Piezoelectrics

Bi and Co substituted stoichiometric bismuth sodium titanate based lead free piezoelectrics,(Bi0.5+x/2 Na0.5-x/2)0.94 Ba0.06 Ti1-xCoxO3, were prepared by using a solid-state reaction method. The effects of combined A/B sites defects on polarization hysteresis and electric-induced-strain properties of materials were explored. It is shown that single pseudocubic structure is revealed in all samples. Substitution leads to downward shift of the ferroelectric-relaxor transition temperature and increase in strain. Meanwhile, the samples exhibit high strain of 0.458% and inverse piezoelectric coefficient d33(9) of 770 pm/V, accompanied by an increased fraction of relaxor phase during fatigue test. The anomalies in temperature dependent dielectrics and hysteresis loops are highly related to the formation of A/B sites defect dipoles which mediated by oxygen vacancies in stoichiometric ceramics.