Phase Diagrams

· The effect of a single freezing or zone pass on the impurity distribution in a sample is illustrated.
· At the first end to freeze, both techniques reduce the impurity concentration to kC₀, where C₀ is the average impurity content of the starting material and k is the distribution coefficient of the impurity.
· Because of the smaller size of its liquid region, the impurity concentration in the zone refined material more rapidly increases with length than in the freezing process.

From: Pfann, "Zone Refining,"
Scientific American 217 (1967) 63