Optimizing electrostrain in textured PNN-PHT piezoceramics through defect engineering

The piezoelectric properties of lead-based ceramics can be enhanced by A -site doping with rare earth elements and texture engineering. However, the effects of defect engineering and the mechanism of enhancing the unipolar electrostrain need to be further explored. This study aims to investigate the microscopic properties and changes in defect dipoles in lead piezoceramics with Sm-doping and texture engineering. Specifically, temperature-dependent XRD and Raman tests showed that texture engineering exhibited remarkable structural stability, and a systematic test was conducted on the temperature stability of the piezoelectric constant d 33 , which fully confirmed a significant positive correlation between the temperature stability and the structural stability of the piezoceramics. Additionally, the epitaxial process induced a high density of interfacial defects due to lattice mismatch, which was analyzed by EPR testing. We observed a 41 % increase in the concentration of oxygen vacancies with texture engineering, but this was reduced by 19 % with 1 % Sm-doping. Furthermore, the buffer layer formed by Sm-doping helps to mitigate the rotation of the BO 6 octahedron during the epitaxy process, resulting in a 29 % reduction in Raman peak broadening. The changes in the defect dipole displacement polarizabilities after Sm-doping were also calculated through defect engineering. The mechanism of high unipolar electrostrain was explored by examining the variations between oxygen vacancy concentration, defect dipole displacement polarizabilities, internal bias field, asymmetry, and leakage current. These results demonstrate the feasibility of texture engineering for high electrostrain through defect engineering and have significant implications for optimizing the reliability of piezoelectric devices in high-temperature environments.