| 研究課題/領域番号 |
25820334
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| 研究種目 |
若手研究(B)
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| 研究機関 | 九州大学 |
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研究代表者 |
ペリー ニコラ 九州大学, カーボンニュートラル・エネルギー国際研究所, 学術研究員 (90645665)
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| 研究期間 (年度) |
2013-04-01 – 2015-03-31
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| キーワード | thin films / oxygen exchange rate / surface chemistry / solid oxide fuel cell / cathode / pulsed laser deposition / impedance spectroscopy / electronic structure |
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| 研究概要 |
1. Two setups for characterization of cathode performance under light illumination were made, and model (La,Sr)(Ti,Fe)O3-δ thin film cathodes with controlled geometries were fabricated using pulsed laser deposition.
2. The influence of La donor doping on cathode defect chemistry, Fermi level, oxygen exchange rate, and aging rate was characterized in situ using ac impedance spectroscopy of asymmetric and symmetric cells, optical absorption relaxation, in plane conductivity measurements, and defect thermodynamic modeling.
3. Performance was correlated to outer monolayer surface chemistry using low energy ion scattering.
4. Results show the impact of donor doping on p-type cathode performance and the relationship between chemistry, electronic structure, and surface oxygen exchange rate.
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| 現在までの達成度 (区分) |
現在までの達成度 (区分)
2: おおむね順調に進展している
理由
Stage 1 (FY 2013, fabrication of in situ illumination setups and fabrication of thin film cathodes) has been completed.
Stage 2 (FY 2013-2014, measurement of oxygen surface exchange rate and conductivity) has been partially completed. Oxygen exchange rate and electrical conductivity have been measured. Geometric dependence of the cathode area-specific resistance needs to be finished, and in situ light illumination studies are just beginning.
Stage 3 (FY 2014, characterization of defect chemistry- electronic structure relationships) is almost complete for the case of La doping. The influence of light and other chemical modification on electronic structure and defect chemistry will be studied in the future.
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| 今後の研究の推進方策 |
In FY2013 the research focused on the effect of La donor doping of the Sr site in Sr(Ti,Fe)O3-δ to raise the Fermi level. La did raise the Fermi level and improved the short-term aging rate but not the long-term performance, owing to non-electronic defect compensation and Sr surface segregation. In FY2014 other strategies will be pursued to modify the electronic structure, including chemical substitution on the (Ti,Fe) site to modify the valence band, and light illumination to optically promote electron transfer to the adsorbed oxygen. It is expected that these new approaches will enhance the oxygen exchange rate and further clarify the relationship between cathode electronic structure and performance.
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| 次年度の研究費の使用計画 |
More expenditures are anticipated in the second year of this project than in the first, but originally I had allocated most of the budget to the first year. It was decided to save more of the Kakenhi budget for FY2014, to purchase research instrumentation, consumables, and instrument time in the second year of the project as well as travel to conferences to present this research.
FY2014 amount of use (B-A) is greater than zero. Instead this amount will be used in FY2014 for: (1) travel costs associated with research presentations at international conferences and conducting research with international collaborators, (2) any costs associated with publishing the work from FY2013 in international journals, (3) chemicals for fabrication of new pulsed laser deposition targets for the new chemistries to be studied, (4) gases for pulsed laser deposition and in situ characterization, (5) additional components to improve the light illumination setup, (6) additional substrates for thin film deposition, (7) consumables relating to electrical characterization, and (8) instrument costs relating to high resolution surface chemistry analysis.
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