Technetium vapor pressure

In consequences of the great differences in vapor pressures of the heptoxides and acids at low temperatures, technetium may be partially separated from rhenium by repeated alternating evaporation with nitric acid and hydrochloric acid ]... 

The property of pcrtcchnctate to be reduced by hydrochloric acid can be used for separating Re04 from reduced TcOj by distillation in a mixture of H2SO4 and HCl at 180 °C [8]. Under these conditions most of rhenium passes into the distillate, but almost all the technetium remains in solution. Another distillation procedure involves reduction of 1 c04 by hydroxylamine. Perrhcnic acid is distilled with steam from sulphuric acid. Up to 10 mg of rhenium can be separated quantitatively from traces of technetium [105]. Partial separation of TcOj from ReO.i is achieved by distillation from perchloric acid, because the first fraction is enriched by technetium. However, ruthenium is oxidized by perchloric acid to RUO4 and volatilizes together with technetium [104]. Due to considerable differences in vapor pressures of H l c04 and HRe04, technetium may be almost quantitatively separated from rhenium by alternate evaporation with nitric and hydrochloric acid [106]. 

J cO.i was identified from the mass spectra as a significant vapor species, present in substantial concentrations, when undefined technetium oxide material was exposed to low pressures of oxygen and heated to 900 °C [36]. 

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