Achieving both giant d₃₃ and high T_c in patassium-sodium niobate ternary system

Both giant d₃₃ and high T_C have been obtained in a lead-free piezoelectric ternary system (0.995 - x)K_0.48Na _0.52NbO₃-0.005BiScO₃-xBi_0.5(Na _0.7K_0.2Li_0.1)_0.5ZrO₃. Thanks to the rhombohedral-tetragonal phase coexistence and the enhanced dielectric and ferroelectric properties, the ceramic with a composition of x = 0.04 shows a giant d₃₃ of ∼366 pC/N together with T_C of ∼335 C, thereby paving the way for achieving both high d₃₃ and high T_C in KNN-based materials. In addition, such a ceramic has a good thermal stability of d₃₃ (e.g., d₃₃ > 319 pC/N, T ≤ 300 °C) and an enhanced stability of ferroelectric properties against temperature. The domain-wall energy barrier of ∼0.15 eV is derived from the temperature dependence of the back-switching polarization.