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

Abstract

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 (MnNb′′′, MnK·, MnNa·) concentration decrease and defects (MnNb′) increase. Defect dipoles (MnK·-VK′, MnNa·-VNa′, MnNb′′′-Vo··) 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 (MnK·-VK′, MnNa·-VNa′) 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 (T90 =210 °C).