Phase Transition and Electrical Properties of Li‐and Ta‐Substituted (Na 0.52 K 0.48 )(Nb 0.96 Sb 0.04 )O 3 Piezoelectric Ceramics

Lead‐free (Na 0.52 K 0.48− x )(Nb 0.96− x Sb 0.04 )O 3 – x LiTaO 3 ceramics ( x =0.0375–0.0575) have been manufactured by a conventional solid‐state method. All compositions form solid solutions with a pure perovskite structure. A morphotropic phase boundary (MPB) between orthorhombic ( x ≤0.04) and tetragonal ( x ≥0.045) ferroelectric phases was identified in the composition range of the 0.04< x <0.045. The composition near the MPB ( x =0.0425) exhibits the best electrical properties with a dielectric constant of 1644, a piezoelectric constant of 310 pC/N, a planar‐mode electromechanical coupling factor of 0.48, and a Curie temperature of 340°C. The results indicate that the materials studied could be a promising lead‐free piezoelectric candidate for device applications.