Physics Colloquium: Imaging Nanoscale Disorder in Reciprocal Space

Thursday, February 13, 2020

3:30 PM-4:30 PM

Ray Osborn, PhD, Argonne National Lab

 

Correlated disorder is responsible for the functional properties of many materials that underpin energy-related technologies. Single-crystal diffuse scattering using x-rays or neutrons is a powerful probe of short-range order in crystalline lattices, but its use has been limited by the experimental challenge of collecting data over a sufficiently large volume of reciprocal space and the theoretical challenge of modeling the results. However, instrumental and computational advances at both x-ray and neutron sources now allow the efficient measurement and rapid transformation of reciprocal space data into three-dimensional pair distribution functions, providing model-independent “images” of nanoscale disorder in real space. By eliminating Bragg peaks before the transformation, these 3D-∆PDF measurements reveal defect-defect correlations directly, displaying only the probabilities of interatomic vectors that deviate from the average structure.1 I will give examples of the use of this method to probe short-range correlations of intercalants in battery cathodes, frustrated 2D order at a metal-insulator transition, and order-disorder fluctuations in a 3D charge-density-wave system.

[1] M. J. Krogstad, S. Rosenkranz, J. M. Wozniak, G. Jennings, J. P. C. Ruff, J. T. Vaughey, and R. Osborn, Nat Mater 19, 63 (2020).

Contact Information

Professor Goran Karapetrov
goran@drexel.edu