Dielectric and Piezoelectric Properties of Modified (Na,K)NbO₃, Ceramics Substituted with KNbO₃

Abstract

In this study, in order to develop lead-free composition ceramics for piezoelectric devices, (1-x)[(Li_0.04(Na_0.56K_0.44)_0.96(Nb_0.90Ta_0.10)_0.998Zn_0.005O₃]—xKNbO₃ (x = 0–7.5 mol%) composition ceramics were fabricated by a conventional sintering technique. The influences of KNbO₃ on the microstructure, the dielectric, ferroelectric and piezoelectric properties of the ceramics were investigated. The results of XRD patterns show that the structure of specimen exhibits a tetragonal structure. The SEM images indicate that the grain size increased with increasing the content of KNbO₃ substitution. Optimum physical properties of piezoelectric constant d₃₃ = 255 pC/N, electromechanical coupling factor k_p = 0.4358, dielectric constant ϵ_r = 699, measured density (ρ) = 4.49 g/cm³ were obtained from the composition ceramic with x = 3 mol%. These results indicate that the (1−x)LNKNTZ-xKN ceramic is a promising lead-free candidate material for practical piezoelectric device applications.

Keywords:

• Lead-free ceramic
• KNbO₃
• NKN
• piezoelectric constant (d₃₃)

Acknowledgments

This work was supported by the Power Generation & Electricity Delivery of the Korean Institute of Energy Technology Evaluation and Planning (KETEP) grant funded by the Korean government Ministry of Knowledge Economy (No. 2010T100100282) and was partially supported by Basic Science Research Program through NRF funded by the Ministry of Education, Science and Technology (No. 2010-0022117).