Lead-free Piezoelectrics Based on Alkaline Niobates: Synthesis, Sintering and Microstructure

The objective of this review is to focus on the processing of ceramics based on sodium potassium niobate (K0.5Na0.5NbO3) as promising candidates for lead-free piezoelectrics. In the first part the review addresses the synthesis of the perovskite solid solution as well as the issue of chemical homogeneity for pure and chemically modified K0.5Na0.5NbO3. The second part covers the sintering and typically encountered bimodal microstructure of K0.5Na0.5NbO3, possible methods of controlling the grain growth and template-assisted grain growth resulting in alkaline niobate single crystals.