Hall effect, point defects

Owing to their non-metallic character and to the very low defect concentrations, the techniques for studying point defects in these materials are quite different from those presented in Section 2 they consist mainly of electrical measurements (conductivity. Hall effect. 

Examples include hypercrystals and quantum Hall effect bubble solids. At finite temperatures all crystals contain point defects. Usually the effect of this for simple crystals can be neglected, but in the case of unusual crystalline materials the effect of an unit cell chemical potential can be dramatic (Mladek, Charbonneau and FVenkel 2007). 

Point defects, which we will see later, are often important intermediate forms in the heterogenous reactions and are detected by various techniques sueh as electric conductivity. Hall effect, photoelectronic effect, and spectroscopy in the visible and ultraviolet range. Techniques of luminescence are also helpfiil. 

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