High Temperature-Insensitive Electrostrain Obtained in (K, Na)NbO3-Based Lead-Free Piezoceramics

Over the last decades, notable progress is achieved in (K, Na)NbO3 (KNN)-based lead-free piezoceramics. However, more studies are conducted to increase its piezoelectric charge coefficient (d(33)). For actuator applications, piezoceramics need high electric-field induced strain under low electric fields while maintaining exceptional temperature stability across a wide temperature range. In this study, this work developes Li/Sb-codoped KNN (LKNNS) ceramics with high electrostrain by defect engineering and domain engineering. A remarkable strain of 0.43%, along with a giant d(33)* value of 2177 pm V-1, is attained in the LKNNS ceramic at 20 kV cm(-1). The ceramic exhibits a minimal performance decrease of less than 15% over a temperature range from room temperature to 150 degrees C. The exceptional strain is attributed to the presence of A-site vacancy-oxygen vacancy V-A '-V-O(center dot center dot) defect dipoles and the increase in nano-domains. The hierarchical domain configuration and V-A(')-V(O)(center dot center dot)poles impede the switched domains from reverting to their original state as temperature increases, furthermore, the elongated dipole moments of V-A '-V(O)(center dot center dot )caused by rising temperatures compensate for strain reduction results in exceptional temperature stability. This study provides a model for designing piezoelectric materials with exceptional overall performance under low electric fields and across a wide temperature range.