Commercially available gases contain residual impurities leading to a
background oxygen partial pressure of typically several 10^{-6} bar,
independent of temperature. This oxygen partial pressure is inappropriate for
the growth of some single crystals where the desired oxidation state possesses
a narrow stability field. Equilibrium thermodynamic calculations allow the
determination of dynamic atmosphere compositions yielding such self adjusting
and temperature dependent oxygen partial pressures, that crystals like ZnO,
Ga2O3, or Fe{1-x}O can be grown from the melt.Comment: 4 pages, 3 figures, talk on CGCT-4 Sendai, May 21-24, 200