MASS SPECTROMETRIC STUDIES AT HIGH TEMPERATURES .22. STABILITIES OF TANTALUM PENTAFLUORIDE AND TANTALUM OXYTRIFLUORIDE

A mass spectrometer was used to study equilibria among vapor species produced by reactions between tantalum and MnF2, between tantalum and mixtures of MnF2 and MnO, and between Ta2O5 and MnF2 in a Knudsen effusion cell. TaF5 and Mn, MnF, and MnF2 were identified in the Ta-MnF2 system, while TaF5, TaOF3, and Mn, MnF, and MnF2 were found in the Ta-MnO-MnF2 and Ta2O5-MnF2 systems. Heats of reactions involving these molecules were evaluated and used to calculate the heats of atomization of TaF5(g) and TaOF3(g).