Temperature-insensitive electric-field-induced strain and enhanced piezoelectric properties of <001> textured (K,Na)NbO₃-based lead-free piezoceramics

Texturing is an effective method to improve the piezoelectric properties of lead-free piezoceramics. In the present study, textured (K,Na)NbO₃-based piezoceramics with a Lotgering factor of 89.7% were successfully fabricated by the templated grain growth (TGG) method. Compared with its non-textured counterparts, great enhancements of the piezoelectric coefficient (50% improvement) and electromechanical coupling factor are observed in the textured samples. More importantly, electric-field-induced strain is also remarkably improved, as evident by a 17% higher large-signal piezoelectric coefficient (346 pm/V) of the textured sample. A relatively low strain deviation of 2% is observed between room temperature and 150 °C, and even up to 175 °C, 86% of their room temperature large-signal piezoelectric coefficient value is maintained. This temperature stability of textured (K,Na)NbO₃-based piezoceramics is of great significance for actuators with a stable response over a broad temperature range.