Vaporisation studies on tellurium dioxide: A Knudsen effusion mass spectrometric study

Abstract The vaporisation of TeO 2 (s) was studied by Knudsen effusion mass spectrometry. The vapour phase was found to consist of (TeO 2 ) n (n = 1−3)(g), (TeO) n (g) (n = 1−3) and Te 2 (g). The p − T relations of TeO 2 (g), (TeO 2 ) 2 (g) and (TeO 2 ) 3 (g) were derived to be log( p /Pa) = (−13534 ± 78)/ T + (14.241 ± 0.09) (750–950 K), log( p /Pa) = (−14823 ± 212)/T + (14.373 ± 0.242) (825–950 K) and log( p /Pa) = (−19074 ± 540)/ T + (17.337 ± 0.606) (850–921 K) respectively. From the partial pressures, Δ r H 298.15 0 of n TeO 2 (s) = (TeO 2 ) n (g) ( n = 1–3) were evaluated by second and third law methods. Also, enthalpy of the pressure independent reaction TeO 2 (s) + TeO 2 (g) = (TeO 2 ) 2 (g) has been evaluated. Using the Δ f H 298.15 0 of TeO 2 (s), Δ f H 298.15 0 of (Te0 2 ) n (g) ( n = 1–3) were calculated. The partial pressure and enthalpy data for (TeO 2 ) 3 (g) have been obtained for the first time.