Ultra-pure Zn, Cd, Ga, In, Ge, Sn, As, Sb or Bi are prepared from the corresponding impure element by converting the impure element into a corresponding alkyl or alkyl hydride derivative and decomposing it to deposit the desired ultra-pure element. The alkyl or alkyl hydride derivative may be purified before decomposition by fractional or steam distillation, zone melting or recrystallization. For example, gallium alkyls such as tri-propyl/ butyl-gallium may be heated at 180-200 DEG C. under an inert atmosphere in a quartz flask fitted with a condenser, the separated metallic gallium being freed from any alkyl-Ga by washing with n-hexane which is later decanted off. An indium regulus may be obtained by heating tri-ethyl/propyl/butyl-indium at 180 DEG C. under a nitrogen atmosphere. Crystalline antimony may be grown on an internally heated quartz rod or cylindrical graphite from the vapour of tri-ethyl/propyl/butyl-antimony. Similarly tin may be deposited on a quartz rod from tetra-ethyl/butyl tin. Other examples specify compounds of triethylbismuth diethylcadmium and diethylzinc. Specification 981,685 is referred to.
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