ABSTRACT
There is a vast array of physical methods for investigating the structures of solids, each technique with its own strengths and weaknesses-some techniques are able to investigate the local coordination around a particular atom or its electronic properties, whereas others are suited to elucidating the long-range order of the structures. Others investigate just the surface structure. No book could do justice to all the techniques on offer, so we describe just some of the more commonly available techniques and try to show what information can be gleaned from each one and its limitations. We start with X-ray diffraction by powders and single crystals. Single crystal X-ray diffraction is used to determine precisely the atomic positions and therefore, the bond lengths (to a few tens of picometres*) and bond angles of molecules within the unit cell. It gives an overall, average picture of a long-range ordered structure, but is less suited for giving information on the structural positions of defects, dopants and nonstoichiometric regions. It is often very difcult to grow single crystals, but most solids can be made as crystalline powders. Powder X-ray diffraction is probably the most commonly employed technique in solid-state inorganic chemistry and has many uses, from analysis and assessing the phase purity, to determining the structure. Single crystal X-ray diffraction techniques have provided us with the crystal structures which are used as the basis for interpreting powder diffraction data.
