Hydrothermal Synthesis of (K,Na)NbO3 Particles

(K,Na)NbO3 (KNN) particles were successfully prepared by hydrothermal synthesis. The results showed that Na+ reacted more readily with Nb to form NaNbO3 than K+. For the purpose of obtaining KNN particles with K/Na=1, a mixed alkaline solution with K+/Na+ ratios ranging from 3.5/1 to 4/1 was required as a starting solution. The morphology and size of KNN particles synthesized strongly depended on K/Na ratio in the KNN particles. The KNN particles synthesized from the starting alkaline solution with K+/Na+=3.5/1 were the smallest with a pelletlike morphology affected by NaNbO3- and KNbO3-based particles. Surfactants such as sodium dodecylbenzenesulfonate (SDBS) and sodium hexametaphosphate (SH) were used to synthesize well dispersed and small KNN particles. Platelike KNN particles with 100 nm thickness and 1.5 µm width were obtained in this study.