Simultaneous determination of several crystal structures from powder mixtures: the combination of powder X-ray diffraction, band-target entropy minimization and Rietveld methods

Crystal structure determination is the key to a detailed understanding of crystalline materials and their properties. This requires either single crystals or high-quality single-phase powder X-ray diffraction data. The present contribution demonstrates a novel method to reconstruct single-phase powder diffraction data from diffraction patterns of mixtures of several components and subsequently to determine the individual crystal structures. The new method does not require recourse to any database of known materials but relies purely on numerical separation of the mixture data into individual component diffractograms. The resulting diffractograms can subsequently be treated like single-phase powder diffraction data, i.e. indexing, structure solution and Rietveld refinement. This development opens up a host of new opportunities in materials science and related areas. For example, crystal structures can now be determined at much earlier stages when only impure samples or polymorphic mixtures are available.