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 MnO 2 as raw materials have an impact on defects in KNN-based ceramics. When the dopant changes from MnO to MnO 2 , the defects (Mn Nb ′ ′ ′ , Mn K · , Mn Na ·) concentration decrease and defects (Mn Nb ′) increase. Defect dipoles (Mn K · - V K ′ , Mn Na · - V Na ′ , Mn Nb ′ ′ ′ - V o ··) in poled and aged 0.94 K 0.48 Na 0.52 Nb 0.96 Ta 0.04 O 3 -0.06BaZrO 3 + 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 · - V K ′ , Mn Na · - 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 °C). [ABSTRACT FROM AUTHOR]