Welcome to the Greer Group



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Fractal nanotruss made by Nigel and Lucas

The key focus of the Greer group is on creating and studying advanced materials that utilize combination of 3-dimensional hierarchical architectures and nanoscale material size effects . Creation of extremely strong yet ultra-light materials can be achieved by capitalizing on the hi­e­r­a­­r­chical design of 3-dimensional nano-architectures. Such structural meta-materials exhibit superior thermo­mechanical pro­­­per­­ties at ex­tre­me­ly low mass densities (lighter than aerogels), making these solid foams ideal for many scientific and tech­no­lo­gi­cal applications. The dominant de­for­mation mechanisms in such “meta-materials”, where individual constituent size (nanometers to microns) is compa­rable to the characteristic microstructural length scale of the constituent solid, are essentially un­known. To harness the lucrative properties of 3-dimensional hierarchical nanostructures, it is critical to assess mechanical properties at each relevant scale while capturing the over­all structural complexity.

Hollow Nano-Truss. The polymer truss is etched out after coating leaving the hollow TiN nano-truss.
(Image courtesy of D. Jang)

We fabricate 3-dimensional nano-lattices whose constituents vary in materials (ceramics, metals, metallic glasses, semiconductors, etc.) and in size from several nanometers to tens of microns to millimeters. We study the deformation and mechanical properties of a range of nano-sized solids with different microstructures by using in-situ nano mechanical experiments and atomistic simulations. We focus on investigating the interplay between the internal critical microstructural length scale of materials and their external limitations in revealing the physical mecha­nisms which govern the mechanical deformation, where competing material- and structure-induced size effects drive overall properties.

We focus on the deformation and failure in metallic, ceramic, and glassy nano structures and discuss size effects in nanomaterials in the framework of mechanics and physics of defects. Specific examples include: fabrication and characterization of hierarchical 3-dimensional architected meta-materials for applications in biomedical devices, ultra lightweight batteries, and damage-tolerant cellular solids, nano-mechanical experiments, flaw sensitivity in fracture of nano structures.


Watch: Julia speaks at the World Economic Conference in Davos

Watch: Julia speaks at Google Solve for X 2014

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Group News
Oct. 2014: Congratulations to Arturo on passing his qualification exam!
Sep. 2014: Julia speaks at TEDxCERN in Geneva, Switzerland! (video coming soon!)
Sep. 2014: Lucas's new Science paper is featured on Caltech's front page!
Aug. 2014: Congratulations to (now-Dr.) Wendy Gu on defending her dissertation!
Aug. 2014: Congratulations to the wonderful SURF students on their final presentations!
Jul. 2014: Nigel and Viki present talks at the Nanostructure Fabrication GRC.
May 2014 : Julia is listed among the 100 Most Creative People in Business 2014 by Fast Company!
Apr. 2014: Julia receives the Keck Futures Initiative Award from the National Academies! Read here.
Apr. 2014: Viki, Rachel, Wendy, Chen, and Seok-Woo present talks at the MRS conference in San Francisco.
Mar. 2014: Nisha passes her Ph.D. defense! Congratulations!
Mar. 2014: Congratulations to Ottman for winning the NSF Graduate Research Fellowship and Viki and Arturo for receiving honorable mentions!
Feb. 2014: Greer Group invades TMS 2014. David, Lauren, Lucas, Nico, Chen, Rachel, Seok-Woo, Viki, Wendy, Zach and Julia gives talks and present posters on their work at the TMS.
Feb. 2014: Julia presents her solution at Google Solve for X!
Jan. 2014: Julia and colleagues Paul Sternberg and Axel Scherer lead IdeasLab with Caltech at the World Economic Forum.
Dec. 2013: Lauren, Viki, Jan and David present talks at the MRS conference in Boston.
Nov. 2013: Julia attends the National Academies' Keck Future Initiatives symposium.
Oct. 2013: Zach presents a talk at the ARL-MEDE conference in Baltimore.
Oct. 2013: Wendy, Lucas and Julia attend and present talks at the ECI Conference on Nanomechanical Testing in Faro, Portugal.
Sept 2013: Dongchan, Lucas, and Lauren's work featured on Caltech's frontpage. Read the paper here!
July 2013: Congratulations to Lauren for passing her candidacy!