This project develops and applies metrologies and standards for characterizing microstructure and dynamics in heterogeneous or porous materials of technological importance over multiple length scales in situ and in operando.
New technologies increasingly harness materials phenomena that operate across many length-scales: e.g., in selective gas adsorption, additive manufacturing, new alloy designs, or in advanced concretes. To overcome technology barriers, these multi-scale material processes must be measured and understood in operando, and it is no longer sufficient just to characterize the materials within which such processes occur. Rather, it is the phenomena or processes, themselves, which must be measured and characterized.
The objective is to develop metrologies and standards, together with structural, thermodynamic and kinetics data for in operando multi-scale microstructure and dynamics measurement in heterogeneous or porous material systems that can support new and sustainable technologies not fully realized at the present time.
Innovative in situ / in operando X-ray & neutron scattering methods have elucidated a wide range of multi-scale processes in technological materials, with recent papers in CrystEngComm, Environmental Science & Technology, Dental Materials, Langmuir, Cement & Concrete Research, Journal of Alloys & Compounds, Journal of Applied Crystallography, Acta Materialia,..
Major results have been obtained relevant to Additive Manufacturing processes for metals & alloys – especially in regard to the appearance of undesired deleterious phases during post-build stress-relief heat treatments.
Structural & microstructural changes in both natural and advanced manufactured gas sorbents have been correlated with selective gas adsorption & desorption processes relevant to carbon mitigation, enhanced oil & gas recovery, & catalysis.
Our partnership with the APS at Argonne National Laboratory has resulted in the development of a world-class synchrotron X-ray based materials measurement facility, allowing fully quantitative characterization over the sub-nanoscale to micrometer-scale range within a few minutes. Collaboration with both the APS and NCNR has produced enhanced experimental sample environments for both facilities.
A new NIST Standard Reference Material, SRM 3600, has been issued for the absolute intensity calibration of small-angle X-ray scattering intensity.
In parallel with its other accomplishments, this partnership with the APS has enabled two unique complementary measurement paradigms to be developed:
The coherent component of the synchrotron X-ray beam has been exploited in combining the USAXS capabilities with X-ray photon correlation spectroscopy (XPCS). The USAXS/XPCS technique allows particle dynamics or changing local microstructural arrangements to be probed directly when other more conventional techniques are not sensitive.
The USAXS capabilities have also been combined with X-ray imaging to enable USAXS contrast imaging and USAXS tomography measurements to be developed. These methods enable heterogeneous features to be highlighted, compared to more conventional X-ray imaging techniques.
Development of these methods to address both NIST mission objectives and the APS user program remains ongoing.