A facile route for the preparation of morphology-controlled NaTaO3 films

Ternary metal oxide films have being attracting increasing attention because of their special properties and potential applications in many important areas. In this paper, we report a facile hydrothermal route for the preparation of NaTaO3 thin films on tantalum foils with controlled morphology. In the NaOH solution, the morphology of crystals in the resultant NaTaO3 film changed from nanocubes to irregular nanoparticles, and then to meshwork of connected nanobranches as the synthesis temperature increased. The evolution of the NaTaO3 crystal morphology was different when hydrogen peroxide (H2O2) was added to the NaOH solution as an oxidizer. In the H2O2-added NaOH solution, the resultant NaTaO3 crystal morphology evolved from nanopyramids to nanoplates, and then to nanospheres with increasing the hydrothermal treatment temperature. The results of this study indicated that the synthesis temperature and the presence of H2O2 collaboratively strongly affected the NaTaO3 particle morphology in the films. The change of the NaTaO3 particle morphology was explained by the two dissolution-crystallization processes and the Oswald ripening effect.