Non-crystalline diffraction - Elucidating local structure of functional materials.

Long-range order can be determined routinely to a high degree of accuracy by analysing the discrete Bragg peak positions and intensities. However, short-range order information, such as defect geometry, is contained in the diffuse scattering intensity. This local structure is critical to the efficacy of many modern materials and devices, such as catalysts, battery materials, magnetic materials and some molecular solids etc.

The project aims to study a number of materials from various groups and focus on the short-range aperiodic deviations from the long-range crystallographic order. The primary technique will be PDF (Pair Distribution Function) analysis, which provides the distribution of atomic distances within a material - amorphous or crystalline. Fundamental to the technique is the ability to collect scattering data to a sufficiently high angle and this project would initially rely on data collections at central facilities and collaborations with other UK universities.

A natural partner to PDF is SAXS (Small Angle X-ray Scattering) which extracts scattering domain size information from low angle data and provides additional information on non-crystalline structure. A further and potentially very productive extension to SAXS (and later PDF) is non-ambient measurements such as variable temperature and atmospheres - equipment for this would become available early in the project.

As with any new technique, the early days of the project will entail investigation of well-chosen systems to provide a grounding in the basics of data collection and structure refinement and build a set of repeatable results and methods. Data analysis would initially use XPDFSuite; however, this would be augmented and extended to include computational and combinatorial approaches.

The project will develop to look at more complex systems and seek to explore the limits of the technique and identify avenues for novel approaches. At this stage it will start to produce results capable of moving associated research forward.