In situ SAXS and SANS Measurements to Overcome Materials Technology Barriers
Andrew J. Allen
For over 50 years microstructure characterization by small-angle X-ray and neutron scattering (SAXS and SANS) has successfully addressed challenges and surmounted technical barriers impeding the development and application of technological materials. These successes have applied across the entire range from "soft" polymeric or biological materials to "hard" materials, such as steels and cements. In some cases, SAXS or SANS has revealed new insights regarding solid or void structural components governing key material properties. Elsewhere, absolute intensity calibration of the data and consequent determination of absolute scattering volume fractions, number densities or surface areas has proved critical in resolving materials design issues. Currently, SAXS and SANS are increasingly being applied to study processes in materials of technological interest by following the resulting microstructural changes in real time under realistic in situ conditions. The advantages of SAXS and SANS in studies of material processes directly relate to those for microstructure characterization in general: both techniques provide non-destructive, statistically-representative quantitative, ensemble measures of the time-dependent effects of the process on the material microstructure – with much improved time resolution in recent years at synchrotron X-ray sources and high-flux neutron sources. Examples of in-situ SAXS and SANS overcoming materials technology barriers include studies of cement hydration, high-temperature annealing of thermal barrier coatings, solution-mediated nanoparticle formation and dissolution, and the selective adsorption / desorption of carbon dioxide in new solid sorbent metal organic framework materials. However, to satisfy the requirements for in situ measurements under increasingly realistic conditions, more ambitious sample environments must be developed for both SAXS and SANS, and synchrotron-based SAXS must use higher X-ray energies.
SAS 2012 Extended Abstracts
small angle neutron scattering, small angle X-ray scattering, microstructure characterization, materials