Simultaneously improving piezoelectric strain and temperature stability of KNN-based ceramics via defect design

Piezoelectric strain and its temperature stability of KNN-based ceramics sintered in reducing atmosphere are improved simultaneously via defects design of Mn doping. MnO and MnO2 as raw materials have an impact on defects in KNN-based ceramics. When the dopant changes from MnO to MnO2, the defects (Mn-Nb ''', Mn-K(center dot), Mn-Na(center dot)) concentration decrease and defects (Mn-Nb') increase. Defect dipoles (Mn-K(center dot)-V-K', Mn-Na(center dot)-V-Na', Mn-Nb '''-V-o(center dot center dot)) in poled and aged 0.94 K0.48Na0.52Nb0.96Ta0.04O3-0.06BaZrO3 + 0.08MnO ceramics form a strong restoring force for domain switching, which enhances the reversibility of the non-180. domains switching and then significantly improves piezoelectric strain. The stable defect dipoles ( Mn-K(center dot)-V-K', Mn-Na(center dot)-V-Na') form so that the reversibility of the non-180. domains switching can be preserved to high temperature. This defect dipoles design provides a general method to achieve large piezoelectric strain (582 pm/V@20 kV/cm) and excellent temperature stability (T-90 =210 degrees C).