Preparation of Co₄W₆O₂₁(OH)₂·4H₂O via Microwave Hydrothermal Method and its Reaction Process

Abstract:

A new kind cobalt tungstate in Co₄W₆O₂₁(OH)₂·4H₂O was smoothly synthesized by microwave hydrothermal process lasting for 80min at 190°C, in which Co (NO₃)₂·6H₂O and Na₂WO₄·2H₂O of analytical grade were selected as raw materials as well as the pH values adjusted from 3 to 5.5. Furthermore, the phase structure and the morphology of target products were characterized by X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM). Additionally, the absorption spectrum of these samples was detected by UV-Vis spectrophotometer. The results showed that the cobalt tungstate in Co₄W₆O₂₁ (OH)₂·4H₂O structure belonged to the cubic crystal system with the lattice constant of 12.858Å and its micro geometric configuration tended to be rhombic dodecahedron. On the condition of pH value at four is best for the propagation of crystals. Moreover, in the absorption spectrum it is indicated that the band gap width of this materials equaled to 3.18eV at pH=4 while 3.81eV at pH=5.

• Periodical: Materials Science Forum (Volumes 809-810)
• Pages: 288-293
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.809-810.288
• Online since: December 2014
• Authors: Xiu Juan He, Li Yun Cao, Xin Gang Kong, Jian Feng Huang*, Jian Peng Wu
• Keywords: Co₄W₆O₂₁(OH)₂·4H₂O, Crystal Structure, Microwave Hydrothermal Method, Reaction Conditions, Reaction Process

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