Atomic fluorine in thermal reactions involving solid TbF4

The Knudsen cell mass spectrometry method has been applied in order to investigate TbF 4 (s) thermal decomposition and solid-phase fluorination reactions in the CoF 3 (s)–TbF 4 (s) system. It has been found that atomic fluorine is the main component of the gas phase during TbF 4 (s) decomposition, and no equilibrium is established between atomic and molecular fluorine at T =600–640 K. It is supposed that solid-phase reaction of fluorination includes the formation of an intermediate with participation of CoF 3 and TbF 4 in the condensed phase. The decomposition of the intermediate leads to the evaporation of CoF 4 molecules into the gas phase.