ABSTRACT
It is well established that no crystal is perfect; hence, in crystals produced either naturally or articially, one would always nd deviations from the ideal structure. These deviations may be in terms of compositional inhomogeneities, impurities, or defects, and all of these inuence most of the physical properties of the crystal. Even sophisticated measurements, when carried out on bad crystal, may give misleading results. Hence, characterization of a crystal is a prerequisite for a meaningful interpretation of the obtained results. It is also important from the application point of view.
