Background to earlier work

The extraordinary feature of this process is that over a period of time, random CS planes can become ordered, with regularly spaced CS planes separated by slabs of an unperturbed parent matrix, leading to new phases. The overall stoichiometry of such a crystal depends on the spacing of the CS planes and the matrix slabs. At certain levels of anion deficiency this will produce the so- 

Some earlier thermodynamic studies on rutile reported expressions involving simple idealized quasi-chemical equilibrium constants for point defect equilibria (see, e.g., Kofstad 1972) by correlating the composition x in TiOx with a function of AGm (O2), which is the partial molar free energy of oxygen. However, the structural effects were not accounted for in these considerations. Careful measurements of AGm (O2) in the TiOjc system (Bursill and Hyde 1971) have indicated that complete equilibrium is rarely achieved in non-stoichiometric rutile. 

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