Sintering Behavior of Lead-Free (K,Na)NbO3-BasedPiezoelectric Ceramics

Abstract

In this manuscript, we investigate the sintering behavior of (K,Na)NbO3 (KNN)-based ceramics covering unmodified KNN, (K,Na,Li)NbO3 (KNLN), and KNLN-xBaTiO(3) (KNLN-BT) systems. Three stages of sintering were identified using detailed temperature and time dependent microscopy. The first stage corresponds to rearrangement of random shape particle to form stack of plate type particles. The second stage is characterized by rapid grain growth promoted by formation of liquid phase. The liquid phase was identified to be Na-deficient composition. In the final stage of sintering, densification slows and microstructural coarsening becomes the dominant process. The fraction control of liquid phase was an important factor to obtain dense and uniform microstructure by completely filling the voids between the plate-shaped particle stacks.