Anisotropic and tunable characteristics of the colloidal behavior of metal oxide surfaces

The electroosmotic behavior of the rutile polymorph of titanium dioxide was explored as a function of crystallographic orientation. Atomic force microscopy (AFM) was employed to make high-resolution force spectroscopy measurements between a silica sphere attached to a traditional, contact-mode AFM cantilever and TiO2 (110), (100), and (001) surfaces in aqueous solutions. Measurements were taken in a variety of solution conditions across a broad range of pH values, and the resultant force-distance curves were used to deduce relative behaviors of each orientation of rutile, with particular interest in changes of the isoelectric point (iep). Differences in iep as a function of orientation are explained in terms of differences in both the coordination number and density of (Lewis) acidic and basic sites on the surface. The results were supported by angle-resolved X-ray photoelectron spectroscopy (XPS) measurements of a nominal monolayer of palladium metal deposited on each of the three orientations studied. The palladium monolayer served as a means of probing the relative electron affinities of the three surfaces studied, which was exhibited in shifts of the palladium XPS peak that corresponded to differences in binding energy as a function of substrate orientation.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Materials Science and Engineering.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2006

Author dc:creator

• Bullard, Joseph Warren, 1978-

Advisor dc:contributor.advisor

• Michael J Cima.

• Materials Science and Engineering.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/37372

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/37372