A NEW ROUTE FOR THE SYNTHESIS OF TUNGSTEN-OXIDE BRONZES

A novel method involving ambient temperature reduction of aqueous solutions has been developed for the synthesis of tungsten oxide bronzes. Addition of aqueous sodium borohydride solution into aqueous sodium tungstate solution at pH almost-equal-to 6.5 results in the formation of a reduced sodium tungsten oxide gel. The gel crystallizes sharply at around 440-degrees-C to yield the crystalline sodium tungsten oxide bronze, NaxWO3. The products are characterized by X-ray powder diffraction and Differential Scanning Calorimetry. (C) 1994 Academic Press, Inc.