Hydrothermal and Solvothermal Preparation of Nanocrystalline KTN Powders

By using Nb2O5 and Ta2O5 as precursors, nanocrystalline potassium tantalite niobate KTa0.6Nb0.4O3 (KTN) powders were prepared by hydrothermal and solvothermal (isopropyl alcohol) synthesis processing. The relations of crystal structure and the synthesis conditions of KTN powders were investigated. All results of measurement on samples obtained demonstrate that the microstructure and morphology of nanocrystal powders depend on the reaction temperature, pressure and pH values of solvents. The reaction solvents are very important factors. The KTN with pyrochlore structure fabricated by the hydrothermal method shows although the amounts of pyrochlore phase in samples decrease gradually as the pH values of solvents increasing, pure perovskite phase will be gained first and last. KTN ceramic powders with perovskite structure were successfully synthesized via solvothermal processing with 1-2mol/L of KOH at 523K for 8h. The SEM images of powders show that the shape of particles is mainly cubic and the size of particles is 30-50nm.