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Mochel, J.M. Contrata, Walter 2011-05-07T13:45:17Z 2011-05-07T13:45:17Z 10000-01-01 1992 The structure of solvent deposited (Au, Au-Ag, Pt) and vapor deposited (Cu) metal particles $\approx$10-40 A A was studied by electron microdiffraction in a STEM. A CCD array recorded the microdiffraction patterns with high sensitivity and dynamic range, and low noise Microdiffraction patterns were classified according to whether they had distinct Bragg peaks, or were diffuse. Patterns with distinct Bragg peaks showed low rates of twinning, with an upper bound of $\approx$14 $\pm$ 3% in the case of Au-Ag particles. Diffuse patterns indicate that many of the particles are highly disordered, $\approx$88% in the case of Au particles. The effects of the electron beam on Pt particles were studied further. Crystalline Pt particles up to 40A in diameter become disordered after exposures ranging from less than a second up to 40 minutes. Disordered particles' diffraction patterns were dynamic, with flickers of intensity lasting $\approx$15 msec (the resolution of the video tape). Pt particles on an amorphous C substrate remained disordered $\approx$20 min before recrystallizing. The dynamic nature and persistance of the disordered state are reminiscent of Ajayan and Marks's quasimelting theory. Made available in DSpace on 2011-05-07T13:45:17Z (GMT). No. of bitstreams: 2 license.txt: 4922 bytes, checksum: 910b249b4beec47e7ab768910c8f966f (MD5) 9215799.pdf: 3891449 bytes, checksum: cffc4f51927d59d0e4822051ee521650 (MD5) Previous issue date: 1992 Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Howard Ding (hding2@illinois.edu) on 2011-05-07T14:58:46Z Item is restricted indefinitely. Restriction data tranferred 2014-07-01T11:27:40-05:00 Original Data Group with Access UIUC Users [automated] Release Date: none Reason: ETDs are only available to UIUC Users without author permission ETDs are only available to UIUC Users without author permission U of I Only AAI9215799 (UMI)AAI9215799 http://hdl.handle.net/2142/22606 eng Copyright 1992 Contrata, Walter Physics, Molecular Physics, Condensed Matter Structure and melting of small metal particles observed by stem microdiffraction text Physics Physics University of Illinois at Urbana-Champaign Dissertation Ph.D.