Tailoring the Size and Shape-New Path for Ammonium Metavanadate Synthesis.

Ammonium metavanadate, NH4VO3, plays an important role in the preparation of vanadium oxides and other ammonium compounds, such as NH4V3O8, (NH4)2V3O8, and NH4V4O10, which were found to possess interesting electrochemical properties. In this work, a new route for the synthesis of NH4VO3 is proposed by mixing an organic ammonium salt and V2O5 in a suitable solvent. The one-step procedure is carried out at room temperature. Additionally, the need for pH control and use of oxidants necessary in known methods is eliminated. The mechanism of the NH4VO3 formation is explained. It is presented that it is possible to tailor the morphology and size of the obtained NH4VO3 crystals, depending on the combination of reagents. Nano- and microcrystals of NH4VO3 are obtained and used as precursors in the hydrothermal synthesis of higher ammonium vanadates. It is proven that the size of the precursor particles can significantly affect the physical and chemical properties of the resulting products.