A Joint Foundry/ALS Seminar
Seminar Date: Tuesday, June 17, 2025
Time: 11:00 AM PT
Location: 67-3111 & Zoom
Talk Title: Nanocrystals under High Pressures, and their Applications
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Abstract:
The structural stability and mechanical behavior of nanocrystals differ from that of bulk crystalline materials due to the proximity of surfaces. In situ studies, in which the evolution of microstructure and properties is monitored during mechanical loading, are challenging at the small length scales and time scales relevant to defect dynamics in nanocrystals. Here, I will discuss the use of high-pressure diamond anvil cell techniques to investigate the deformation of nanocrystals and nanoclusters of down to ~20 metal atoms in size. X-ray diffraction, optical spectroscopy and modeling are used to understand elasticity and plasticity at pressures of up to ~50 GPa. This provides insight into the motion of defects at surfaces, the nature of metallic bonding, and deformation induced optical changes. Findings from these fundamental studies are then used in 3D printing and optical sensing. Metallic nanoclusters are used as photoinitiators and inorganic precursors in novel two-photon lithography resins that enable the nano 3D printing of nanocomposites and nanoporous glassy carbon with high strength and energy absorption per weight. Pressure-sensitive upconverting nanoparticles are used as ingestible mechanosensors to study forces within C. elegans roundworms in-vivo.
Bio:
Dr. Wendy Gu has been an Assistant Professor of Mechanical Engineering at Stanford University since 2017. Before this, Wendy received her MS/PhD from Caltech in 2014, and was a postdoc at UC Berkeley from 2015-2017. Her research focuses on developing lightweight architected materials, nanostructured metals and structural alloys with superior strength and toughness, including for hydrogen environments and high pressure conditions. Major techniques within the group include nano-mechanical testing and in-situ imaging using transmission and scanning electron microscopy, and synchrotron X-ray diffraction and tomography, nano-synthesis and self-assembly, and 3D printing. Wendy is the recipient of the DOE Early Career Award, the ARO Young Investigator Award, the ACS Petroleum Research Fund Doctoral New Investigator Award, and the Hellman Scholar Award.
