Preparation and Characterization of Cu₃V₂O₇(OH)₂·2H₂O Hollow Spheres from Na₂V₆O₁₆·3H₂O Nanobelts

Monoclinic Cu₃V₂O₇(OH)2·2H₂O(copper polyvanadate) hollow spheres were prepared with Na₂V₆O1₁₆·3H₂O nanobelts as V-precursor by hydrothermal method. The purity and structure of the products were characterized by X-ray powder diffraction(XRD), Fourier transform infrared(FTIR) spectroscopy, Raman spectroscopy, thermogravimetric analysis(TGA) and X-ray photoelecton spectroscopy(XPS). The morphology and size were observed by scanning electron microscopy(SEM). We found that the Kagomé staircase-structural copper polyvanadate hollow spheres with an average diameter of 7 μm could be easily synthesized via the reaction of Na₂V₆O₁₆·3H₂O nanobelts with sufficient copper sulfate. The dielectric property of the copper polyvanadate demonstrates that dielectric loss hardly changes when the frequency of applied electric field is higher than 100 kHz. The formation process of the hollow spheres is discussed in detail by the observation of a series of products prepared for different reaction time.