Vaporization behavior of TeO2(s): a quantitative vaporization-Knudsen effusion mass spectrometric study

A high temperature mass spectrometric study of solid tellurium-di-oxide was conducted in conjunction with the 'quantitative vaporization method'. This study differs from our previous work [J. Nucl. Mater. 247 (1997) 28] essentially on two accounts: in situ pressure calibration and partial pressures from ion intensities corresponding to a low electron-impact energy of 13 eV. Focus was on the species TeO2(g), TeO(g), Te2(g), (TeO2)2(g), and (TeO)2(g). When compared to the results deduced from our previous measurements, no significant change was observed in the relative abundance of these gaseous species, but the absolute partial pressures were higher by a factor of 1.8. The p-T relations were obtained for these gaseous species in the temperature range 805-905 K. Enthalpies of various homogeneous gas-phase and heterogeneous gas-solid reactions were deduced, and so were the enthalpies of formation of (Te + O) gaseous species. The discrepancies amongst different mass spectrometric studies with regard to the absolute partial pressures and the p(TeO)/p(TeO2) and p(Te2)/p(TeO) ratios are brought out.