Morphology control and phase transition of hexagonal sodium niobate particles

Hexagonal NaNbO3 particles with an ilmenite structure and plate-like morphology were synthesized by a hydrothermal method. The morphological evolution of the solid products with the increasing mineralizer concentration was monitored via SEM during the hydrothermal reaction. By carefully controlling the mineralizer concentration, particles with a diameter of 10-60 µm and a thickness of 1-10 µm were obtained. The particles were transformed from the ilmenite structure into the perovskite structure during the thermal treatment at 600 °C. Their plate-like morphology was maintained with some cracking on the surface. The surface orientation of the perovskite particles was micro- and macroscopically characterized by EBSD and XRD analysis, respectively. The results indicate that thinner particles tend to be more oriented in the (00 l) crystal planes.