Effects of Zn Substitution on Dielectric and Piezoelectric Properties of (Na0.54K0.46)0.96Li0.04(Nb0.90Ta0.10)O3 Ceramics

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In this study, in order to develop lead-free composition ceramics for piezoelectric actuator and sensor applications, (Na0.54K0.46)0.96 Li0.04(Nb0.90Ta0.10)1-2x/5ZnxO3 (x = 0{\mbox{--}}1.5 mol %) composition ceramics were fabricated by a conventional sintering technique at 1110 °C for 5 h. The piezoelectric properties of resultant ceramics were studied with a special emphasis on the influence of Zn-substitution amount. The crystal structure of the specimen exhibited a pure perovskite phase with the coexistence of two phases (orthorhombic and tetragonal phases). However, the phases included tetragonal-rich phases to some extent. The scanning electron microscopy (SEM) images indicated that grain size increased with increasing the content of Zn substitution. High physical properties, namely, piezoelectric constant d_{33} = 265 pC/N, electromechanical coupling factor k_{\text{p}} = 47.5%, dielectric constant \varepsilon_{\text{r}} = 1223, and measured density \rho = 4.84 g/cm3 were obtained from the composition ceramic with x = 0.5 mol %. The mechanical quality factor (Q_{\text{m}}) was improved from 54 of pure (Na0.54K0.46)0.96Li0.04(Nb0.90Ta0.10)O3 (abbreviated as NKLNT) to 106 by 1.5 mol % Zn substitution. The results reflect that the material is a promising candidate for lead-free high-performance piezoelectric device applications, such as piezoelectric actuators and sensors.
2012-09-25