Disordering of small metal particles in a scanning transmission electron microscope
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|---|---|---|
1997_vanfleet.pdf
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1997 Vanfleet |
| Title: | Disordering of small metal particles in a scanning transmission electron microscope |
| Author(s): | Vanfleet, Richard R. |
| Director of Research: | Mochel, J. M. |
| Department / Program: | Physics |
| Discipline: | Physics |
| Degree: | Ph.D. |
| Genre: | Dissertation |
| Subject(s): |
Scanning Transmission Electron Microscope (STEM)
platinum palladium rhodium iridium electron scattering in metals diffraction patten thermodynamics small metal particles |
| Abstract: | Small metal particles in the range of a few nanometers in diameter are seen to progressively disorder when the 100 keV electron beam of a Scanning Transmission Electron Microscope (STEM) is held stationary on the particle. The diffraction pattern of the individual particle is seen to progress from an initial array of indexable diffraction spots to a mixture of diffraction spots and amorphous-like rings and finally to rings with no persistent diffraction spots. Only particles below a critical size are seen to fully disorder. We have observed this disordering in Platinum, Palladium, Rhodium, and Iridium and have developed a model for the disordering process. In this model, electrons scattering from surface atoms transfer enough energy to break the surface atoms from their binding site. A competing process of disordered atoms rebinding to crystalline sites is also included. Because small particles have large fractions of their atoms on the surface, the beam driven disorder, under certain conditions, is able to propagate into the core of the particle. For Platinum, surface disordering requires energy transfers from the electrons to the Platinum atoms of0.54 eV. |
| Issue Date: | 1997 |
| Genre: | Dissertation / Thesis |
| Type: | Text |
| Language: | English |
| URI: | http://hdl.handle.net/2142/30770 |
| Rights Information: | © 1997 Richard R. Vanfleet |
| Date Available in IDEALS: | 2012-04-26 |
| Identifier in Online Catalog: | 4048920 |
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This item appears in the following Collection(s)
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Dissertations and Theses - Physics
Dissertations in Physics -
Graduate Theses and Dissertations at Illinois
Graduate Theses and Dissertations at Illinois
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