Sodium silicate added Na_(0.50)K_(0.50)NbO_3 piezoceramics prepared by ceramic technique using ball milling

摘要

Potassium sodium niobate commonly known as KNN is an eminent candidate among the lead free piezoceramics to replace lead based ceramics. However, low densification is one of the main difficulties in the preparation of KNN piezoceramics. Moreover, various dopants, as well as different additives, are added to KNN and its based piezoceramics to improve density, microstructure, desired stoichiometry as well as piezoelectric properties. Sodium silicate commonly known as water glass is one of the additives which is water soluble and found highly efficient in improving microstructural development and hence densification. In the present work, KNN piezoceramics having compositional formula Na_(0.50)K_(0.50)NbO_3 added with different amount of sodium silicate (0wt.%, 0.5wt.%, 1wt.%, 1.5wt.%) have been prepared by a ceramic technique using ball milling. The samples were calcined at 850°C for 3h and sintered at 950°C for 2h by conventional heating technique. X-ray diffraction (XRD) technique confirms an orthorhombic phase formation in the samples. The crystallite size of the prepared samples was calculated and the numerical value varied from 37-77nm. The highest d_(33)～77pC/N has been obtained at Na_(0.50)K_(0.50)NbO_3 added with 1.5 wt.% sodium silicate. The effect of the addition of different amount of sodium silicate in Na_(0.50)K_(0.50)NbO_3 piezoceramics on the electrical properties (dielectric constant, dielectric loss and a. c. conductivity) and the microstructural morphology have been analyzed and systematically discussed in this paper.