Temperature-related oxygen nonstoichiometry

As described in Section 1,1, both the procedures of changing Po. at fixed temperature and changing temperature at fixed Po. control the nonstoichiometry in Nii O, Let us consider the relation between a and 3 in Nil O, in which the non-stoichiometry S is believed to originate from metal vacancies. By use of the notation based on the effective charge, described in Section 1,3,7, the chemical equilibrium between the oxygen gas in the atmosphere and the oxygen in the solid may be expressed as... 

The diffusion coefficient of oxygen was first obtained theoretically in its relation to the degree of nonstoichiometry by Thorn and Winslow (246, 260,300) for nonstoichiometric UOj+ t, while more recently Contamin et at. (292) have reported for the temperature range from 400 to 900 C with X = 0.006 0.16 the empirical relation... 

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