Large recoverable electrostrain in Mn-doped (Ba,Sr) TiO3 ceramics

In this letter we demonstrate that with a different principle, BaTiO3 ceramics, so far considered as inferior piezoelectrics compared with Pb(Zr,Ti)O-3 (PZT), can show a large recoverable electrostrain. This principle utilizes a point-defect-mediated reversible domain switching mechanism, which can in theory generate 0.368% strain for BaTiO3 ceramics at the best condition. Experimental results showed that, after aging at room temperature, 1.0 mol % Mn-doped (Ba0.95Sr0.05)TiO3 ceramics generate a large recoverable nonlinear strain of about 0.12%-0.15% at a field of 3 kV/mm. This value exceeds that of conventional hard PZT piezoelectric ceramics. A microscopic model for the domain-related electrostrain effect in ceramics is proposed. It is also found that the large electrostrain effect is quite stable with respect to both changing frequency and fatigue cycles. Large electrostrain remains recoverable down to 0.05 Hz and after 10 000 cycles. These results demonstrate the potential of our approach in achieving large recoverable electrostrain in environmental-friendly (Pb-free) ceramics. (C) 2004 American Institute of Physics.