Studies on the hydrothermal synthesis of niobium oxides

Hydrothermal reactions of commercial Nb2O5 with aqueous MOH, M=Na, K, at 200 °C and autogenic pressure provided new routes to different niobium compounds. The reaction of Nb2O5 with NaOH was used to synthesize NaNbO3 under mild conditions. The known room-temperature phase was obtained and identified by infrared spectroscopy and X-ray powder diffraction. In similar conditions, reactions of Nb2O5 with KOH yielded alkaline aqueous solutions containing soluble potassium hexaniobates. Those solutions were used to prepare K6H2[Nb6O19]·13H2O and niobic acid. Hydrothermal reactions of commercial Nb2O5 with aqueous MOH, M=Na, K, provided thus a more convenient process of attack to niobium pentoxide than the traditional method of fusion of mixtures of the niobium oxide with alkali metal hydroxides or carbonates.

Hydrothermal reactions of commercial Nb2O5 with aqueous MOH, M=Na, K, at 200 °C and autogenic pressure provided new routes to niobium compounds. The reaction of Nb2O5 with NaOH was used to synthesize microcrystalline NaNbO3. Under similar conditions reactions of Nb2O5 with KOH yielded alkaline aqueous solutions containing soluble potassium hexaniobates.Figure optionsDownload as PowerPoint slide