DETERMINING MEDIUM-RANGE ORDER BY POWDER DIFFRACTION

The method of atomic pair-distribution function (PDF) analysis of powder diffraction data, applied to the study of short-to-medium range atomic order in crystalline solids, is described. In real crystalline materials local atomic order is sometimes significantly different from the long range crystallographic lattice structure, due to lattice defects or some other local effects. While various physical properties are affected by such short and intermediate range order, there is not a wealth of experimental methods that can effectively characterize the local atomic order. We suggest that the PDF method coupled with the real space analysis is one of the most effective tools for this purpose.