STRUCTURE DETERMINATION BY NEUTRON POWDER DIFFRACTION

We extend the discussion of the concepts, techniques and methods of structure determination presented in the companion paper to include aspects of imperfect crystals, with emphasis on neutron powder diffraction. Particular attention is payed to the cases of atomic short-range order (a deviation from randomness) and dislocations (a systematic perturbation of perfect crystallinity). The means for accommodating these structural features in structure analysis procedures are discussed. Generic treatments of particle-size broadening and strain are also mentioned, for both the fixed-wavelength and time-of-flight diffraction techniques.