Effects of Li Substitution in (Na_0.53K_0.47-xLi_x)NbO₃ Ceramics

Abstract

The effects of Li substitution on K in (Na_0.53K_0.47-x Li _x )NbO₃ (NKLN) ceramics prepared by a solid state process were studied at 0 ≤ x ≤ 0.09. Phase purity was maintained up to x = 0.04, then a secondary phase started emerging. With increasing Li substitution, partial melting appeared to occur and grain size increased. Polymorphic phase transition (PPT) temperatures, T _O-T between orthorhombic and tetragonal phases and T _C between tetragonal and cubic phases, were significantly affected by Li substitution. With increasing x, T _O-T decreased while T _C increased extending the tetragonal phase region. The highest d ₃₃ of 220 pC/N was obtained at x = 0.07 mol at which high apparent density of the sintered pellets was obtained despite the formation of an impurity phase.

Keywords:

• Pb-free sodium potassium lithium niobate
• polymorphic phase transition
• piezoelectric coefficient

Acknowledgment

This work was supported by the National Research Foundation of Korea (NRF) Grant funded by the Korean Government (MEST) (2011-0030805). This research was also supported by Basic Science Research Program through the National Research Foundation (NRF) of Korea funded by the Ministry of Education, Science and Technology (2011-0026389).