THERMOCHEMICAL AND KINETIC-STUDIES ON THTE2O6

ThTe2O6 was prepared by a solid-solid reaction route and was character ized by X-ray diffraction and thermal methods. Thermal studies show th at ThTe2O6 vaporizes incongruently as: ThTe2O6(s) double left right ar row ThO2(s) + 2TeO(2)(g). The vapour pressures of TeO2(g) were measure d over ThTe2O6(s)+ ThO2(s) and over TeO2(s, 1) in the temperature rang e 1000-1131 K employing Knudsen cell mass loss technique. From the par tial pressures of TeO2(g), the standard Gibbs free energy of formation (Delta(f)G degrees) of ThTe2O6(s) was derived and it can be represent ed by the equation: Delta(f)G degrees(ThTe2O6, s, T) +/- 21.0 kJ/mol= -1943.2 + 0.5506T (K), (1000 K < T < 1131 K). The kinetics of decompos ition under isothermal heating conditions in flowing air were studied to determine the activation energy, reaction mechanism and rate consta nts.