Annealing Induced Diffusion Dynamics in As Ion-Implanted GaAs

Crude hexafluoroacetone (HFA) containing chlorofluoroacetone(s) (CFA) as well as hydrogen halide(s) is purified by initially allowing the crude HFA to be absorbed in water to give an aqueous solution in which HFA and CFA are in the form of their respective hydrates, adding a calcium compound such as carbonate, hydroxide or oxide to the solution to neutralize the hydrogen halide(s), and decomposing the hydrated CFA by first adding an alkali metal compound such as K2CO3 or Na2CO3 or an alkaline earth metal compound such as Ca(OH)2, Ba(OH)2, CaO or BaO to the solution and subsequently adding a mineral acid such as HCl or H2SO4 to the same solution. This procedure results in complete decomposition of CFA without causing decomposition of HFA and spontaneous separation of the liquid reaction system into two layers, one of which is exclusively HFA hydrate. Accordingly it is easy to separate pure HFA hydrate from the decomposed impurities.