Phase Structures and Piezoelectric Properties of (K,Na,Li)(Nb,Sb)O3-(Bi,Ag)ZrO3 Lead-Free Ceramics

Samples in the pseudoternary lead-free piezoelectric ceramic system 0.94KNN-(0.06 − x)LiSbO3-x(Bi0.5Ag0.5)ZrO3 were prepared using a solid-state reaction technique and their phase transition behavior and electrical properties studied. Results showed that BAZ diffuses into KNN-LS to form a new solid solution, and induces a phase transition from tetragonal to rhombohedral phase with increase of x. At 0.02 ≤ x ≤ 0.03, coexistence of tetragonal and rhombohedral phases is observed, and enhanced piezoelectric properties are achieved in this composition range due to the polymorphic phase transition near room temperature. Doping with (Bi0.5Ag0.5)ZrO3 effectively promotes densification and further enhances the piezoelectric and dielectric properties of of the ceramics. Moreover, the ceramic with x = 0.025 possesses excellent electrical properties of kp = 42.3%, d33∗\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${d_{33}^{*}}$$\end{document} = 320 pm/V and d33 = 235 pC/N, tan δ = 0.039, and Tc = 326°C. This result indicates that 0.94KNN-0.035LS-0.025BAZ ceramic is a promising lead-free material for practical applications.