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Physical Vapor Deposition |
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Metal and metal oxide nanoparticles grown at the steps of highly oriented pyrolytic graphite (HOPG) by members of the Hemminger Group include, gold, silver, aluminum oxide, titanium dioxide, and iron oxide. The physical vapor deposition pocess involves placing a metal slug into a W basket that may or may not be covered with an aluminum oxide ceramic. Upon heating the basket, metal atoms evaporate and deposit onto the graphite substrate.
By heating the substrate during deposition, the thermal energy induces adatom mobility. With sufficient thermal energy, the adatoms can move to the steps and nucleate to form linear nanoparticle arrays.
For the metal oxide (i.e. titanium dioxide) nanoparticles, the metal (i.e. titanium) is likely oxidized by the residual oxygen in the evaporator/coater during the physical vapor deposition process. As one might expect, the interaction between the metal adatoms and the graphite substrate affects the amount of thermal energy necessary to fabricate the nanoparticle arrays. For example, the higher binding and diffusion barrier energy of Ti than Au on graphene requires a higher substrate temperature to grow the titanium dixoide nanoparticle arrays. In the menu at the left, select "Research Projects" to read more on the projects related to these nanoparticle arrays.
Photodeposition of Ag or Pt onto TiO2 Nanoparticles Decorated on Step Edges of HOPG Polarization-dependent surface enhanced Raman
scattering from silver 1D nanoparticle arrays Physical vapor deposition of one-dimensional nanoparticle arrays
on graphite: Seeding the Electrodeposition of gold nanowires (something related to iron oxide nanoparticles and pyrite)
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