On thermal dissociation of ammonium complex fluorides of zirconium and hafnium

It has been established by thermogravimetric and roentgenographic methods that the process of thermal dissociation of ammonium heptafluorozirconate and hexafluorozirconate (hafneate) results in the formation of a mixture of (NH4)2Zr(Hf)F6 and NH4Zr(Hf)F5. Using DTA methods, the nature of polymorphic transformations in hexafluorocomplexes has been considered. The kinetics has been studied of decomposition of ammonium complex fluorides in the temperature range of 85-270 deg C. The activation energies have been determined of thermal decomposition reaction of the complexes under consideration. The effect is demostrated of polymorphic transitions in (NH4)2Zr(Hf)F6 on the rate of thermal dissociation of these compounds