Synthesis of Single-Crystalline Plate-shaped K_(0.5)Na_(0.5)NbO_3 Particles by Multi-step Molten Salt Method

摘要

In this study, single-crystalline plate-shaped K_(0.5)Na_(0.5)NbO_3 (KNN) particles were successfully synthesized by a multi-step molten salt method (MMSM). First, precursor particles K_4Nb_6O_(17) (K4N6) with layer-structure was synthesized at 1050 °C in molten KCl-salt (MMSM-1) by starting materials of Nb_2O_5 and K_2CO_3. Second, plate-shaped KNN was synthesized at 1000 °C in molten KCl-NaCl-salt (MMSM-2) from K4N6 particles and K_2CO_3 powders. X-ray diffraction (XRD) analysis revealed that the crystallographic {010} plane of K4N6 was converted into the pseudo-cubic {001} plane of KNN. SEM images showed that MMSM-synthesized KNN particles preserved the shape of K4N6 precursor particles, and had a thickness of about 3～5μm, a width of 10～15μm and a length of 15～20μm. EDX spectrum proved that the K:Na mole ratio was 0.6:0.4. These plate-shaped KNN particles were very promising templates to fabricating textured KNN-based ceramics.