National Synchrotron Light Source Seminar

"Tomography and In situ time-resolved Imaging of Structural Evolution in Nanoporous Gold during Dealloying and Coarsening by Transmission X-ray Microscopy"

Presented by Yu-chen Karen Chen, Northwestern University

Monday, March 7, 2011, 10:30 am — Seminar Room, Bldg. 725

Nanoporous gold has attracted great attentions due to its numerous potential applications in sensors, actuators and catalytic materials. Dealloying of silver-gold alloys result in a sponge-like porous gold structure with 5-20 nm pore size. In order to change the optical and mechanical properties of the materials, their pore size can be further coarsened by post-annealing.
To fully understand the underlying mechanisms of the dealloying and coarsening processes, we characterized the structural evolution of nanoporous gold using the transmission x-ray microscope at Advanced Photon Source. The microscope offers tomography capability and a 30-40 nm 2D resolution. Dealloying of silver-gold was imaged in-situ, within a custom designed chemical reaction cell. Coarsening of nanoporous gold was studied by 3D tomography as function of annealing time and temperatures. The structural evolution and kinetics in dealloying and coarsening will be discussed.
Furthermore, many research fields can potentially benefit from this cutting edge imaging technique, especially with the higher time resolution achievable at third generation synchrotron x-ray sources, which provide high x-ray flux. A few new possible future applications using TXM for time-resolved imaging and nano-tomography will also be discussed.

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