The Formation and Ordering of Shear Planes in Non-stoicheiometric Oxides

The Formation and Ordering of Shear Planes in Non-stoicheiometric Oxides 

The extended defect structures that occur in certain non-stoicheiometric compounds have in recent years provided some of the most intriguing problems in solid-state chemistry. The most intensively studied phase showing this class of disorder is Ti02-x which planar defects known as shear planes have been detected and characterized by electron microscopy. Examples of other simple inorganic compounds containing shear planes are provided by V02 x and The range of 

Until recently very little was understood as to the factors which determine whether point or extended defects are formed in a non-stoicheiometric phase, although interesting empirical correlations between shear-plane formation and both dielectric and lattice dynamical properties of the defective solid had been noted. Theoretical techniques have, however, provided valuable insight into this problem and into the related one of the relative stabilities of extended and point defect structures. The role of these techniques is emphasized in this article. 

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