Zone refining of germanium is carried out on a rod with a heater that moves from the left end to the right end. Let $k = C_{solid} / C_{liquid}$ for an impurity. Which statements are correct?

ASilicon and gallium can also be purified by this method
BAn impurity with $k < 1$ concentrates at the right end
CAn impurity with $k > 1$ concentrates at the left end
DA single pass of the heater gives unlimited purity

Answer: A, B, C

With k<1 the solid is poorer in the impurity, so the melt carries it forward to the right (last to freeze). With k>1 the solid takes up the impurity preferentially so the melt is depleted of it as the zone advances and the impurity accumulates at the left. Si and Ga are also refined this way. Purity improves with repeated passes, not unlimited in one pass.

Practice Metallurgy More on Refining methods: zone refining, van Arkel, Mond process, electrolytic refining

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Zone refining of germanium is carried out on a rod with a heater that moves from the left end to the right end. Let k=Csolid​/Cliquid​ for an impurity. Which statements are correct?

Answer: A, B, C

More questions on Refining methods: zone refining, van Arkel, Mond process, electrolytic refining

Zone refining of germanium is carried out on a rod with a heater that moves from the left end to the right end. Let $k = C_{solid} / C_{liquid}$ for an impurity. Which statements are correct?