Lead-Free Alkali Niobate Piezoelectric Materials

Abstract

Piezoceramics with attractive structural and electrical properties are important for the development of energy harvesters and energy conservation devices. The lead-based piezoelectric ceramics need to be replaced by lead-free piezoceramics because of the toxicity of the lead. Barium titanate (BT), sodium bismuth titanate (BNT), potassium bismuth titanate (KNT), and sodium potassium niobate (KNN) are some lead-free piezo materials. Among the lead-free piezo materials, KNN has a high Curie temperature and attractive electric and piezoelectric properties. The attractive properties of KNN-based ceramics are due to the polymorphic phase boundary observed in KNN ceramics which is similar to the MPB as observed in PZTs. Therefore, KNN has the potential to replace the PZTs. However, it is difficult to get high-density ceramics due to limitations in sintering at high temperatures that can volatilize the alkali elements components. The structural and electrical properties of the material depend on chemical compositions and processing techniques. The addition of oxides as sintering aids, different sintering techniques, and chemical modification improves the density and electrical properties.