User Facilities for X-Ray and Neutron Absorption Spectroscopy - A survey of analyzing material properties when other syntheses don’t provide results!
At the Spring MRS 2019 conference, some of the U.S. Department of Energy’s laboratories held tutorials on their state-of-the-art nanoscale science research centers and user facilities. The Center of Nanophase Materials Sciences (CNMS) at Oak Ridge National Laboratory and the Center for Nanoscale Materials (CNM) at Argonne National Laboratory were prominently featured, with studies that included material local distortions, chemical short range bordering, nanostructuring, and crystallographic phase transitions.
The main tutorial, the ‘Mini X-Ray and Neutron School on In Situ Materials Research’, featured researcher Katharine L. Page (ORNL), where user facilities assessed data via constructing a pair distortion function (PDF), an atomic-level scattering technique, after detection. Chemical short range order via PDF can infer material substitution effects, chemical clustering, ion-specific local environments, and vacancy ordering. Nanomaterial structuring information based on a PDF can also be determined: finite size/shape effects, surface/interface structure, nanostructure polymorphs, and growth/transformation. Such a technique is also transferrable to amorphous structures, where an understanding of oxide liquids, for instance, is essential in nuclear meltdown scenarios, evolution of planetary bodies, glass formation, and crystal nucleation.
Researchers are encouraged to pursue PDF studies if they have already modeled many material parameters possible while in reciprocal space, and if they suspect local material structure may differ from the long-range structure. Evidence of a distinct local structure may be available if one finds signatures of disorder through complementary methods, or if an average structure model fails to explain observed material properties.
The user facilities for such nanoscale science research centers are as follows:
- Center for Nanophase Materials Science at Oak Ridge National Laboratory (cnms.ornl.gov)
- Center for Nanoscale Materials (CNM) at Argonne National Laboratory (anl.gov/cnm)
- Center for Functional Nanomaterials (CFN) at Brookhaven National Laboratory (bnl.gov/cfn)
- Center for Integrated Nanotechnologies (CINT) and Los Alamos and Sandia National Laboratories (cint.lanl.gov)
- The Molecular Foundry (TMF) at Lawrence Berkeley National Laboratory (foundry.lbl.gov)