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dc.contributor.authorAmani Hamedani, Hodaen_US
dc.date.accessioned2009-01-22T15:55:37Z
dc.date.available2009-01-22T15:55:37Z
dc.date.issued2008-11-19en_US
dc.identifier.urihttp://hdl.handle.net/1853/26670
dc.description.abstractSolid oxide fuel cell (SOFC) research is currently underway to improve performance, cost and durability by lowering the operating temperature to ~600°C. One approach is to design fabrication processes capable of tailoring desirable cathode microstructures to enhance mass and charge transfer properties through the porous medium. The aim of this study is to develop a cost effective fabrication technique for deposition of novel microstructures, specifically, functionally graded thin films of LSM oxide with porosity graded structure for use as IT- SOFCs cathode. Spray pyrolysis method was chosen as a low-temperature processing technique for deposition of porous LSM films onto dense YSZ substrates. The effort was directed toward the optimization of the processing conditions for deposition of high quality LSM films with variety of morphologies in the range of dense to porous microstructures. Results of optimization studies on spray parameters revealed that the substrate surface temperature is the most critical parameter influencing the roughness and morphology, porosity, cracking and crystallinity of the film. Physical and chemical properties of deposited thin films such as porosity, morphology, phase crystallinity and compositional homogeneity have shown to be extensively dependent on the deposition temperature as well as solution flow rate and the type of precursor solution among other parameters. The LSM film prepared from organo-metallic precursor and organic solvent showed a homogeneous crack-free microstructure before and after heat treatment as opposed to aqueous solution. Also, increasing the deposition temperature and the solution flow rate, in the specific range of 520-580 ℃ and 0.73-1.58 ml/min, respectively, leads to change the microstructure from a dense to a highly porous film. Taking the advantage of simplicity of spray pyrolysis technique combined with using metal-organic compounds, the conventional ultrasonic spray system was modified to a novel system whereby highly crystalline multi-layered porosity graded LSM cathode with columnar morphology and good electrical conductivity in the range of 500-700 °C was fabricated through a multi-step spray and via applying optimum combination of spray parameters. This achievement for the current graded LSM cathode would allow its use in IT-SOFCs.en_US
dc.publisherGeorgia Institute of Technologyen_US
dc.subjectSOFCsen_US
dc.subjectCathodeen_US
dc.subjectSpray pyrolysisen_US
dc.subjectFGMen_US
dc.subjectPorosityen_US
dc.subjectLSMen_US
dc.subject.lcshSolid oxide fuel cells
dc.subject.lcshCathodes
dc.subject.lcshPyrolysis
dc.subject.lcshLanthanum compounds
dc.titleInvestigation of deposition parameters in ultrasonic spray pyrolysis for fabrication of solid oxide fuel cell cathodeen_US
dc.typeThesisen_US
dc.description.degreeM.S.en_US
dc.contributor.departmentMechanical Engineeringen_US
dc.description.advisorCommittee Chair: Qu, Jianmin; Committee Co-Chair: Garmestani, Hamid; Committee Member: Haynes, Comas; Committee Member: Klaus-Hermann Dahmen; Committee Member: Liu, Meilinen_US


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