Multi-phase transition behaviour and large electrostrain in lead-free (K, Na, Li)NbO3ceramics

Phase transition usually causes significant enhancement in materials properties due to the metastability of the structures and it has been used to enhance useful properties of functional materials. In this work, we report that in (K 1− x Na x ) 0.92 Li 0.08 NbO 3 (0.5 ⩽ x ⩽ 0.9, KNLN) system there exists a composition region where three phases, tetragonal, orthorhombic and rhombohedral, are close in stability. Large electrostrain over 0.14% and high remanent polarization ( P r ) over 20 µ C cm −2 appear in the multi-phase region with 0.65 ⩽ x ⩽ 0.8. The significant enhancement of electrostrain is attributed to the instability of polarization vector and field-induced phase transition in the multi-phase transition region.