K/Na Ratio Dependence of the Electrical Properties of [(K _<i>x</i> Na _{1− <i>x</i>} ) _0.95 Li _0.05 ](Nb _0.95 Ta _0.05 )O ₃ Lead‐Free Ceramics

Abstract

[(K x Na 1 − x ) 0.95 Li 0.05 ](Nb 0.95 Ta 0.05 )O 3 (K x NLNT) ( x= 0.40–0.60) lead‐free piezoelectric ceramics were prepared by conventional solid‐state sintering. The effects of K/Na ratio on the dielectric, piezoelectric, and ferroelectric properties of the K x NLNT ceramics were studied. The experimental results show that the electrical properties strongly depend on the K/Na ratio in the K x NLNT ceramics. The K x NLNT ( x =0.42) ceramics exhibit enhanced properties ( d 33 ∼242 pC/N, k p ∼45.7%, k t ∼47%, T c ∼432°C, T o−t =48°C, ɛ r ∼1040, tanδ∼2.0%, P r ∼26.4 μC/cm 2 , E c ∼10.3 kV/cm). Enhanced electrical properties of the K x NLNT ( x =0.42) ceramics could be attributed to the polymorphic phase transition near room temperature. These results show that the K x NLNT ( x =0.42) ceramic is a promising lead‐free piezoelectric material.