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The synthesis of tungsten trioxide gel by dissolution of tungsten in hydrogen peroxide and its transformations during the heat treatment in oxidation and reduction atmospheres

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Author(s): Georgijević Radovan | Mentus Slavko

Journal: Hemijska Industrija
ISSN 0367-598X

Volume: 65;
Issue: 3;
Start page: 279;
Date: 2011;
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Keywords: electron microscopy | reduction in hydrogen atmosphere | thermal analysis | tungsten | tungsten trioxide

ABSTRACT
The structure and the thermal behavior of WO3 samples in air and in reduction atmosphere were studied. The sample I was prepared by the dissolution of fine metallic tungsten powder in hydrogen peroxide followed by solvent evaporation in the air at 60°C. Sample II was obtained by draining a part of the sample I at 60°C and then heating it up to 430°C. By the means of X-ray diffractometry, scanning electron microscopy and thermal analysis it was evidenced that the sample I was the amorphous hydrated gel, with the WO3•1.5H2O composition, while the second one was the anhidrous monoclinic WO3 with the mean particle size of 100 nm. Additionally, using the thermogravimetric and the differential thermal analysis simultaneously in the reduction atmosphere, both samples types were examined. After reduction the distribution of the metal particles number in respect to the diameters of the anhidrous sample was examined using the electron microscopy.

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