A Duplex Grain Structure of Dense (K, Na)NbO 3 Ceramics Constructed by Using Microcrystalline as Seed

A new raw material was developed for the preparation of dense (K, Na)NbO 3 (KNN) ceramics. In the absence of dopants, two kinds of KNN powder, calcined and microcrystalline powder, were used as matrix and seed to construct a duplex grain structure. The former was synthesized by the traditional solid phase reaction method and the latter by molten salt method. The effects of microcrystalline powder content on sintering behavior, microstructure and electric properties were investigated. It was found that appropriate microcrystalline powder content ( x =0.4) promoted the grain growth and the gas diffusion, which resulted in a denser duplex grain structure and obtained a wide sintering temperature range. This work gives a basic raw material system for the development of high performance KNN ceramics. In addition, it also provides a new way to prepare dense ceramics by the design of a duplex structure.