Modified Re‐Entrant‐Like (K, Na)NbO3‐Based Relaxors with Superior Electrostrain Properties

Abstract Piezoceramics with large strain output, low hysteresis, and wide operation temperature are indispensable for the high‐end displacement control. Unfortunately, requiring these merits simultaneously remains a long‐standing challenge for lead‐free piezoceramics promising for replacing lead‐based ones. Herein a new strategy to resolve this challenge by developing modified re‐entrant‐like potassium sodium niobate ((K, Na)NbO 3 , KNN) relaxors is presented. Multi‐scale structural analysis reveals the presence of the significant local disorder, nano‐sized multi‐phase coexistence, and ultra‐fine grains, which facilitate the polarization rotation, effectively eliminate non‐180° domains, and erase polymorphic phase transition features in re‐entrant‐like KNN relaxors. Consequently, a combination of large strain (≈0.19%), ultra‐low hysteresis (<7%), high electrostriction coefficient ( Q 33 = 0.049 m 4 C −2 ), and benign temperature stability (i.e., strain varies less than 10.6% within 30–120 °C) is realized, superior to other lead‐free relaxors. Therefore, this strategy provides a novel paradigm for designing high‐performance lead‐free piezoceramics used for high‐precision actuators.