“Probing phase behavior and synthetic pathways in situ via high energy x-ray diffraction”

In situ characterization of the phase behavior of materials in the lab is complicated by the difficulty of designing compatible sample environments as well as the long time scales required to acquire diffraction data with sufficient counting statistics for crystallographic analyses. The high energy x-rays available at synchrotron sources allow for penetration of most sample environments, while high flux allows for rapid acquisition of diffraction patterns, thereby allowing construction of detailed phase diagrams or direct observation of synthetic processes. High energy x-ray diffraction techniques have been utilized to probe a variety of physicochemical phenomena. 1) The pressure-dependence of thermal expansion in the ZrW2O8 family of negative thermal expansion materials and the associated changes in tetrahedral ordering have been probed via in situ variable pressure/temperature studies. 2) The phase behavior of corium has been explored at temperatures up to 2850°C. 3) The localization of oxymetallic clusters during atomic layer deposition onto metal organic frameworks has been determined via in situ powder diffraction. 4) The mechanism and intermediates formed during solid-state synthesis of formamidinium lead iodide have been probed via in situ variable temperature diffraction and total scattering measurements.

Leighanne Gallington is currently an Assistant Physicist at Argonne National Laboratory. She graduated from MIT with an SB in Chemistry in 2006. She then joined the Infectious Disease division at Children’s Hospital Boston as a research technician, where she supported research studies of the innate immunity of immunocompromised populations. She resumed her education in 2009 in the School of Chemistry and Biochemistry at Georgia Institute of Technology, and received her doctorate in Physical Chemistry in 2015. The focus of her dissertation was the relationship between structural disorder and the thermoelastic properties of low and negative thermal expansion materials. While at Georgia Tech, she received a Facilitating Academic Careers in Engineering and Science (FACES) fellowship, and participated in NOBCChE outreach events geared toward underrepresented minority middle school students. She began a postdoctoral position at the Advanced Photon Source at Argonne National Laboratory in 2015, where her research focused on utilizing synchrotron diffraction for nonambient studies of a variety of oxymetallic systems. She transitioned to a staff scientist position at Argonne in 2018, and currently supports x-ray total scattering and diffraction experiments in the Structural Sciences group at beamline 11-ID-B.