Experimental methods for structure analysis: X-ray diffraction techniques

Abstract

A crystal is made up by arranging the corresponding unit cells in three directions. If there is an order in the repetition of this unit cell arrangement in space, then only its crystalline nature is manifested. This order is of two types (a) local order and (b) long-range order. When both of these two types of ordering are maintained in space then the crystal is called single crystal, and when the local order is maintained but the long-range order is violated often then the crystalline material is called polycrystal. The region within which these two types of ordering are maintained but the long-range ordering is violated just on its boundary is single crystal region. The size of these regions behaving like single crystals depends on the resolution power of probe which is used to “see” them. The X-ray diffraction patterns from these two types of crystals are obviously different and so also the experimental techniques to get them. In this chapter, the different experimental techniques and the method of their interpretations generally used for the structural studies are discussed for both of these two types of crystalline state of matter, i.e., single and polycrystalline states [1]–[3].