Electrodeposited Au/CoAu multilayered nanowires are materials with alternating layers of Au and CoAu in a wire where the layer thickness and wire diameter are nanometer size. They can be used for different applications. For example, the wires may exhibit giant magnetoresistance (GMR), a change in the materials resistance with a magnetic field, having applications as a sensor material for microdevices. If Co is etched from CoAu nanowires, rough, porous gold nanostructures will be left behind, which could be used as novel catalysts.
In this study, the electrodeposition of Au/CoAu multilayered nanowires and nanotubes in nanoporous templates was explored from a non-cyanide electrolyte. The multilayers were deposited with a pulse current control and the template pore size played an important role in determining whether nanowires or nanotubes were formed. The magnetic and magnetoresistive properties of Au/CoAu multilayered nanostructures were examined. Au/CoAu multilayered thin films exhibited both normal and inverse CIP GMR.
After electrodeposition, the solid nanowires were released from the template and one component was electrochemically etched from the nanowires. The electrochemical etching conditions were predetermined by the investigation of electrochemical etching behavior of CoAu alloy and pure Co thin films. By precisely controlling the electrochemical etching potential and time, the surface area of the nanowires was enhanced. Nano-bamboo structures were created after partial etching and Au nanodisk structures were created after complete etching. Compared to conventional chemical etching, the anodization etching process presented here can be controlled to produce partially etched structures. The anodization process was monitored by two techniques. The current was recorded during etching and the total charge was proportional to the layer size. In addition, cyclic voltammetry (CV) was used as a way to observe the partial etching of the nanowires. In addition, the annealing post-treatment was tested to enhance the magnetoresistive properties of Au/CoAu multilayered nanostructures and to improve the quality of the multilayer interface by promoting phase segregation. Furthermore, hollow nano-bamboo structure and ordered nanorings with various aspect ratios were developed through the electrochemical etching of Au/CoAu nanotubes in a similar way. To the best of the authors knowledge, this has not been done before.
| Identifer | oai:union.ndltd.org:LSU/oai:etd.lsu.edu:etd-01092008-225444 |
| Date | 10 January 2008 |
| Creators | Guan, Maoshi |
| Contributors | W. David Constant, Elizabeth J. Podlaha, Ralph W. Pike, James E. Henry, Michael C. Murphy, Michael L. Cherry |
| Publisher | LSU |
| Source Sets | Louisiana State University |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lsu.edu/docs/available/etd-01092008-225444/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached herein a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to LSU or its agents the non-exclusive license to archive and make accessible, under the conditions specified below and in appropriate University policies, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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