A New Twist on Nanowire Formation

Song Jin (U of Wisconsin-Madison) DMR 0548232

We have discovered a fundamentally different nanowire growth mechanism that is driven by axial screw dislocations, which results in fascinating nanowire trees. In this novel catalyst-free mechanism, the self-perpetuating steps of a screw dislocation spiral provide the fast crystal growth front under low supersaturation during crystal growth. These intriguing trees with helically rotating branches are the clearest demonstration of “Eshelby twist” — the rotation of a crystal lattice around a screw dislocation as the consequence of its associated stress.Dislocation driven nanowire growth is a general mechanism that has been greatly under appreciated. This discovery will create a new dimension in the rational design and synthesis of nanomaterials.

10 μm

C

BA

Bierman, Lau, Schmitt, Kvit & Jin Science 2008, 320, 1060.

D

100 μm

Web Course on Nanoscience and “Nano Boot Camp”

Song Jin (U of Wisconsin-Madison) DMR 0548232

We have developed a web course on nanoscience & nanotechnology for school teachers. As one of the success stories of this course, a former participant, Mr. Joseph Rajkumar from the Conserve School of northern Wisconsin, developed a class on “Introduction to Nanoscience” in Jan 2008. Furthermore, our research group organized and hosted a two-day workshop (called “Nano Boot Camp: Discovering the Nanoscience at UW-Madison”) for the group of high school students taking this class on Jan 14&15, 2008. The students heard introduction talk about nanoscience, toured the research lab and facilities, carried out two lab modules on nanomaterials, and used electron microscope to examine the nanomaterials they made, and also joined a panel discussion about college and graduate study. SEM experiment with

Jeremy HigginsSynthesize your own nanomaterials