The Interaction of Tellurium Dioxide and Water Vapor

The previously reported enhanced volatility of tellurium dioxide due to water vapor has been confirmed over the temperature range 825 to 970°K through vapor pressure measurements with a mass transport apparatus. Investigations of the temperature dependence of the characteristic equilibrium constant yield a value of 30.4 kcal/ mole for the heat of the (assumed) reaction TeO₂(s) + H₂O(g) = TeO(OH)₂(g). Attempts to identify the gaseous hydroxide species through mass spectrometry were unsuccessful. Mass spectrometer studies of TeO₂ vapor, however, indicate ∼20% dimer formation within the temperature range 920 to 1050°K.