AMEROM LLC
Grant: $149,299 - National Science Foundation - Jun. 23, 2009
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Award Description: Skutterudite group (e. g., CoSb3) thermoelectric materials are used to generate electrical power from different heat sources (e. g., stove top generators, engine exhaust powered alternator replacement, self-powered appliances), but the current market is limited by a low ZT values that imposes a constraint on the TE efficiency. With an increased ZT value, CoSb3 processed by the proposed technology can be used in many power conversion devices operating at intermediate temperatures; moreover, it may compete with Bi2Te3 for low temperature applications. The unique combination of electrochemical deposition and surface roughening has great potential for mass production of low-cost and high-efficiency thermoelectric materials that can not be achieved by bulk processing techniques. Additionally, technology proposed here will enhance the scientific and technological understanding of nanostructured thermoelectric materials. To date, most of the work on electrodeposited thermoelectric thin films and nanostructures focuses on synthesis, primarily investigating compositions and structure. A dissonant gap between synthesis and characterization of the thermoelectric properties, namely the Seebeck coefficient and thermoelectric figure of merit, creates only a partial picture for published works on electrodeposited thermoelectric materials. While composition and structure of electrodeposits are crucial indicators of physical properties, their measured thermoelectric performance will ultimately dictate their usefulness for various applications.This Small Business Technology Transfer Phase I project aims at establishing the feasibility of fabricating high-efficiency nanostructured thermoelectric at low cost. CoSb3 skutterudite will be grown by electrochemical deposition using template synthesis. After template removal, a novel controlled surface modification step will be applied to nanowires. We expect this particular surface treatment alone to reduce thermal conductivity of nanostructured CoSb3 to a greater degree compared to electrical conductivity due to differences in their respective scattering lengths. Research will also lead to tailored thermoelectric properties of the nanowire arrays. Nanostructured CoSb3 skutterudite will be grown, doped and treated under various fabrication conditions, and then characterized. We will address some of these challenges regarding both size and surface modification. Complex nanoscale characterization will be performed using electrochemical techniques, X-ray diffraction, electron microscopy (SEM, TEM, EDS and EELS), and X-ray photoelectron spectroscopy (XPS). Measurements of electrical conductivity, thermal conductivity and Seebeck coefficient will be performed to study the efficiency of these nanostructures as a function of wire size, chemical composition and surface roughness in order to obtain an optimal condition for the highest efficiency. This technology lays the foundation for large-scale fabrication of highefficiency thermoelectric devices for energy conversion.
Project Description: We have performed experimental work on electrochemical deposition of CoSb3 thin film and nanowire. Electrochemical studies performed on thin films revealed a nucleation process, which makes more difficult to control the formation of CoSb3 compound. Experiments performed to date revealed the formation of CoSb3 but also free Co and Sb was observed in the film. More experiments are required to find the right conditions for CoSb3 formation. The mecanism of nucleation and growth depends on deposition conditions. Detailed study on CoSb3 deposition has been started in order to understand the nucleation and growth mecanism of CoSb3 on nanostructured surface. These results will be used to grow CoSb2 nanowires with controlled composition.
Jobs Summary: Dr. Ruxandra Vidu, PI: plan and conduct experimental work; plan and conduct characterization work; analyze results and write reports; plan for Phase II submission. Prof. Pieter Stroeve, Co-PI: provide consulting in template synthesis, nanowire growth. Prof. Joanna Groza: Provide consulting in heat treatment and characterization of nanostructures. Dr. Dat V. Quach conduct experimental and characterization work. (Total jobs reported: 2)
Project Status: Less Than 50% Completed
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