Hydrothermal synthesis of sodium niobate with controllable shape and structure

We describe the synthesis of hexagonal NaNbO3 by mixing reactants at high temperature under hydrothermal conditions. The morphological and structural evolution of crystalline NaNbO3 was studied in detail using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, selected area electron diffraction, high-resolution transmission electron microscopy, and Raman techniques. A variety of products in the form of irregular Na8Nb6O19·nH2O bars, microporous monoclinic Na2Nb2O6·nH2O fibers, self-assembled dandelion-like Na2Nb2O6·nH2O structures, and octahedral-shaped hexagonal NaNbO3 have been prepared. The present synthetic strategy enables us to tune the morphologies and structures of the niobate products by controlling the reaction kinetics.