Thermodynamics of gaseous zirconium and hafnium fluorides

Gas-phase equilibria with participation of zirconium and hafnium fluorides were studied in a wide range of temperatures using the MS 1301 magnetic mass-spectrometer. Formation enthalpies of all lower fluorides of hafnium and zirconium were determined. For monofluorides of zirconium and hafnium, as well as tri- and difluorides of hafnium, they were obtained for the first time. On the basis of experimentally obtained data equilibrium composition of vapour in the systems studied and energies of consecutive rupture of bonds in molecules of zirconium and hafnium fluorides were calculated