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近10年来,曾拟出了生产超纯Si、Ge的方法,以及生产其它许多总杂质含量<0.01％的金属的方法,其中杂质往往只有5×10~(-6)(5 PPM),个别元素可低于5×10~(-8)(0.05PPM)。保证达到这种纯度的方法是:先用化学法或理化法制得纯化合物,再从其中还原出纯金属,或用精炼法。纯化合物的制取法如下:①不溶性化合物的二次沉淀,此时必须计及杂质有吸附和同时沉淀的可能;②二次再结晶;③杂质(有时与将其带入沉淀物的附加物一起)的沉淀或分馏;④用有机物液体自水溶液中提取;⑤用离子交换剂进行交换。下表表示从用各种方法净化所得化合物中还原出来的金属的总杂质(X_(10)~(-6))。
In the past 10 years, methods for producing ultra-pure Si and Ge, as well as many other metals with a total impurity content of <0.01%, have been proposed, in which the impurities are usually only 5 × 10 -6 (5 PPM) Elemental may be less than 5 x 10 ~ (-8) (0.05 PPM). To ensure that this purity is achieved: first with chemical or physical and chemical methods of pure compounds, and then restore the pure metal, or refining method. The pure compound preparation method is as follows: ① insoluble compounds secondary precipitation, at this time must take into account the possibility of impurities adsorption and simultaneous precipitation; ② secondary recrystallization; ③ impurities (sometimes with the addition of its precipitate into the precipitate Together) precipitation or fractionation; ④ with organic liquid extracted from the aqueous solution; ⑤ exchanged with ion exchangers. The following table shows the total impurities (X_ (10) ~ (-6)) of the metal reduced from the compounds purified by various methods.