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VERSION:2.0
CALSCALE:GREGORIAN
PRODID:UW-Madison-Physics-Events
BEGIN:VEVENT
SEQUENCE:0
UID:UW-Physics-Event-1191
DTSTART:20080902T170500Z
DURATION:PT1H0M0S
DTSTAMP:20260506T200124Z
LAST-MODIFIED:20080908T172354Z
LOCATION:4274 Chamberlin (Refreshments will be served)
SUMMARY:Complex nanostructures driven by screw-dislocation nanowire gr
 owth\, Chaos & Complex Systems Seminar\, Song Jin\, UW Department of C
 hemistry
DESCRIPTION:I will discuss some complex "Christmas Tree" like nanowire
  structures spontaneously formed through chemical reactions. These fas
 cinating nanostructures demonstrate a ?new? nanowire formation mechani
 sm that is completely different from the well-known metal catalyzed va
 por-liquid-solid (VLS) mechanism. The screw component of an axial disl
 ocation provides the self-perpetuating steps to enable 1-dimensional c
 rystal growth\, unlike previously understood mechanisms that require m
 etal catalysts. This mechanism was found in hierarchical nanostructure
 s of lead sulfide (PbS) nanowires resembling ?pine trees? that were sy
 nthesized via chemical vapor deposition. Structural characterization r
 eveals a screw-like dislocation in the nanowire trunks with helically 
 rotating epitaxial branch nanowires. The rotating trunks and branches 
 are the consequence of the Eshelby twist of screw dislocations. We sug
 gest that screw dislocation growth is overlooked and underappreciated 
 in modern literature on one-dimensional nanomaterials. The proposed na
 nowire growth mechanism will be general to many materials and enable m
 ore complex nanostructures to be synthesized in the future to enable d
 iverse applications.
URL:https://www.physics.wisc.edu/events/?id=1191
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