Disordered Materials operates three neutron time-of-flight diffractometers for the fundamental and applied study of disordered and complex materials. These instruments are SANDALS and GEM (co-operated with the Crystallography group) on Target Station 1, and NIMROD on Target Station 2. The group also runs two PANalytical X-ray diffractometers with Ag and Mo sources, and which are optimised for PDF measurements.
The group specialises in the analysis of total scattering data covering multiple length scales ranging from the atomic up to the nanoscopic regimes, and provides structural insights in to problems in chemistry, physics, materials science, and biology. To this end we support an extensive suite of data reduction and analysis tools, covering the processing of raw neutron data, analysis of target systems through Monte Carlo refinement of the data, and the subsequent extraction of structural properties. See our software page for more information.
What is a Disordered Material?
The two archetypal classes of disordered materials are liquids and glasses. Liquids such as water have no long range order, but do display local correlation and order between molecules. Similarly, silicate glasses such as those used in everyday window panes are not crystalline materials - they are solids with no long range order, but again possess local order between atoms. These subtle structural correlations on the atomic and molecular length scale underpin the macroscopic properties of the material or system. For instance, understanding how to make toughened glass for aeroplane windows right down to mobile phone screens requires knowledge of the atomic structure of the material and the influence of the industrial manufacturing processes employed.
The complementary capabilities of the three ISIS Disordered Materials instruments are manifest in the science programmes they undertake. User community access requests for GEM predominantly focus on the microscopic characterisation of glassy materials. The ability to look at hydrogen with minimal impact from inelastic scattering has allowed SANDALS to develop a program that focusses on hydrogen-containing liquids and glasses, often characterised by hydrogen-bonded interactions. The science programme on NIMROD is driven by its ability to probe structure across a very wide range of length scales and consequently its science driver is nanoscale complexity, for example, the characterisation of liquid structure in nano-confinement.
For specific examples, please take a look at the science highlights pages for GEM, SANDALS, and NIMROD.