Mediating the Contradiction of d33 and TC in Potassium-Sodium Niobate Lead-Free Piezoceramics

For potassium-sodium niobate, the piezoelectric constant (d(33)) was usually improved by sacrificing the Curie temperature (T-C). In this work, a material system of 0.992(K0.46Na0.54)(0.965)Li0.035Nb1-xSbxO3-0.008BiScO(3) has been designed and prepared with the aim of achieving both a large d(33) and a high T-C at the same time. The chemical compositions are found to be homogeneously distributed in the ceramics. The introduction of Sc is found to be responsible for different grain sizes. The rhombohedral-tetragonal phase coexistence zone lies in the composition range of 0.02<x <= 0.06. The ceramic is thermally stable in terms of ferroelectric properties. The change in the domain-wall activities induced by the configuration variation of defect dipoles upon annealing is believed to be responsible for the variation in the d(33) at different temperatures. The ceramic with x=0.025 shows a good comprehensive performance of d(33)approximate to 325 pC/N and k(p)approximate to 48%, together with a high T-C of similar to 358 degrees C, demonstrating that this material system is a promising candidate for high-temperature piezoelectric applications.