•The method was first used for purification (zone
melting), taking advantage of the small segregation
coefficients of many impurities. The impurities
contained in the feed material would then prefer to
remain in the melt and thus could be swept to the
end of the feed stock.
• Since the melt never comes into contact with
anything but vacuum (or inert gases), there is no
incorporation of impurities that the melt picks up by
dissolving the crucible material as in the CZ crystal
growth method. This is especially true for oxygen,
which can not be avoided in CZ crystal growth. FZ
crystals therefore are always used when very low
oxygen concentrations are important.