Effects of Li Substitution on the Physical Properties of Lead-Free (Na_0.54K_0.46)(Nb_0.81Ta_0.15Sb_0.04)O₃ Ceramics

Abstract

In this study, the effects of Li substitution on the physical properties of (Na_0.56K_0.46)(Nb_0.81Ta_0.15Sb_0.04)O₃ ceramics were investigated. From the result of temperature dependence of dielectric constant, orthorhombic - tetragonal phase transition temperature (T_o-t) slightly decreased and the tetragonal-cubic phase transition temperature (T_c) of the ceramics slightly increased as a function of Li substitution. Electromechanical coupling factor (k_p), piezoelectric constant (d₃₃) and dielectric constant (ϵ_r) increased with increasing the content of Li substitution. Excellent properties of electromechanical coupling factor k_p = 0.47, piezoelectric constant d₃₃ = 240 pC/N, dielectric constant ϵ_r = 1646 were obtained in the composition with Li = 4 mol%.

Keywords:

• Lead-free
• Li-substitution
• electromechanical coupling factor (k _p)
• mechanical quality factor (Q_m)

Funding

This work was supported by Basic Science Research Program through NRF funded by the Ministry of Education, Science and Technology (No. 2010-0022117).