A THERMAL-ANALYSIS STUDY OF TUNGSTEN-OXIDE GELS

A simultaneous TG-DTA-MS study was made in a helium flow for an amorph ous gel prepared by the addition of water to an ethanolic solution of tungsten hexachloride before evaporating the solvent at ambient temper ature. Four endothermic mass losses were observed at approx. 40-80, 13 0-170, 190-200 and 210-600 degrees C, The first was attributed to deso rption of hydrochloric acid and water, The second was attributed to th e simultaneous evolution of (1) hydrogen chloride and ethylene, and (2 ) chloroethane. The third occurred very rapidly and was attributed to the same gases as the second loss. The fourth occurred very slowly and was attributed to the desorption of hydrogen chloride. The firing pro cess of the gel was discussed on the basis of the decomposition mechan isms.