Thermochemical study of the gaseous molecules EuNbO3, EuNbO2, EuNb2O6 and of the niobium oxides NbO and NbO2

The gaseous ternary oxide molecules EuNbO3, EuNbO2 and EuNb2O6 have been identified by high temperature mass spectrometry in the vapours in equilibrium over a mixture of europium sesquioxide and niobium monoxide in a molybdenum Knudsen cell over the temperature interval 1996-2382 K. From the study of various all-gas equilibria, the atomization energies and the standard heats of formation for these molecules were derived. In addition, from the study of a gaseous exchange reaction involving EuO, NbO, and NbO2, new results for the niobium oxides were obtained and compared with literature data. (orig./PW)