Thesis
MoO₂: A mixed conductivity oxide for solid oxide fuel cell applications
Washington State University
Master of Science (MS), Washington State University
2014
Handle:
https://hdl.handle.net/2376/103451
Abstract
Molybdenum dioxide (MoO₂) has a number of potential energy applications including use in solid oxide fuel cells and lithium-ion batteries. The synthesis of MoO₂ can be tailored to produce a variety of morphologies and crystal structures. Of the many methods, hydrothermal reduction is a useful approach due to the mild solution conditions and the low reduction temperatures. It is critical to understand the temperature effect on the hydrothermal method because of the commercial potential of MoO₂ and the need to develop viable (i.e., low cost) manufacturing processes. Two specific reduction temperatures were used in this study: 180°C and 200°C. Synthesis at 180°C favored formation of smaller particles, but also resulted in higher carbon concentrations within the resulting powders as compared to MoO₂ synthesized at 200°C. During subsequent processing the carbon can react to form Mo2C. This phase is an undesirable side product for many of the proposed energy applications because it does not show the mixed ionic and electronic conductivity of MoO₂. There is some ambiguity about the electronic conduction mechanism and its temperature dependence. Conductivity data as a function of temperature was rationalized in the framework of the band structure to support the semi-metallic description of MoO₂. AC Hall effect measurements found low electron mobilities for MoO₂ thin films, as expected for d band conduction. The data agreed with a combined conduction model including residual conductivity, low temperature hopping and impurity band conduction from Mo 4d bands degenerate with the conduction band.
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Details
- Title
- MoO₂
- Creators
- Kale Warren Harrison
- Contributors
- M Grant Norton (Chair) - Washington State University, Honors CollegeSu Ha (Committee Member) - Washington State University, Chemical Engineering and Bioengineering, School ofSusan Lynne Dexheimer (Committee Member)Kerry W Hipps (Committee Member) - Washington State University, Chemistry, Department of
- Awarding Institution
- Washington State University
- Academic Unit
- Mechanical and Materials Engineering, School of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; [Pullman, Washington] :
- Identifiers
- 99900525148101842
- Language
- English
- Resource Type
- Thesis