Applications of X‐ray powder diffraction in materials chemistry

Abstract X‐ray powder diffraction is a standard technique in materials chemistry, yet it is often still used in the laboratory as a “one‐hit” technique, e.g. for fingerprinting and following the progress of reactions. It is important, however, that the wealth of information available from powder data is not overlooked. While it is only possible here to scratch the surface of possibilities, a range of examples from our research is used to emphasize some of the more accessible techniques and to highlight successes as well as potential problems. The first example is the study of solid solution formation in the oxide systems Ba 3−3 x La 2 x V 2 O 8 and Sr 4− x Ba x Mn 3 O 10 and in the silicate–hydroxyapatite bioceramic, Ca 10 (PO 4 ) 6− x (SiO 4 ) x (OH) 2− x . Database mining is also explored, using three phases within the pseudobinary phase diagram Li 3 SbO 4 –CuO as examples. All three phases presented different challenges: the structure of Li 3 SbO 4 had been previously reported in higher symmetry than was actually the case, Li 3 Cu 2 SbO 6 was found to be isostructural with Li 2 TiO 3 but the cation ordering had to be rationalized, and Li 3 CuSbO 5 was believed to be triclinic, presenting challenges in indexing the powder pattern. Quantitative phase analysis is briefly discussed, with the emphasis both on success (determination of amorphous phase content in a novel cadmium arsenate phase) and on possible failure (compositional analysis in bone mineral); the reasons for the problems in the latter are also explored. Finally, the use of an area detector system has been shown to be of value in the study of orientational effects (or lack of them) in non‐ and partially‐ordered biomaterials, including p‐HEMA, annulus fibrosis of lumbar discs, and keratin in the horn of cow's hooves. © 2005 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 5: 252–262; 2005: Published online in Wiley InterScience ( www.interscience.wiley.com ) DOI 10.1002/tcr.20050