2020 Fiscal Year Research-status Report
Understanding equilibrium and non-equilibrium dopant segregation towards more stable electrode materials
| Project/Area Number |
18K13992
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| Research Institution | Kyushu University |
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Principal Investigator |
ハリントン ジョージ 九州大学, 持続的共進化地域創成拠点, 特任助教 (20753718)
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| Project Period (FY) |
2018-04-01 – 2022-03-31
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| Keywords | oxides / thin films / segregation / surfaces / grain boundaries |
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| Outline of Annual Research Achievements |
I have demonstrated that the number of point defects, which is critical for both anion and cation diffusion, can be manipulated at interfaces often present in SOFC electrodes. This work was published in the international journal ACS Applied Materials and Interfaces. It was also demonstrated that by controlling the lattice strain in thin film systems, the diffusion could be manipulated as a function of strain and defect-defect interactions, as published in the Journal and Materials Chemistry A. It was shown that the surface exchange of a mixed-ionic electronic conducting material, a potential candidate for solid oxide fuel cell electrodes, could be modified by up to seven orders of magnitude by infiltrating binary oxides onto the surface. Furthermore, the change in surface exchange was directly correlated to the acidity of the infiltrated oxide. This work was published in Nature Catalysts.
I have constructed an exchange rig allowing for oxygen tracer diffusion measurements and have performed tracer diffusion on epitaxial and polycrystalline films of LSM grown by PLD. LSM films have been fabricated on bi-crystal substrates of STO and YSZ to isolate the effects of individual grain boundaries. Oral presentations on the research have been given at the following conferences: ECS in Seattle, E-MRS in Strasburg, Electroceramics in Hassalt, Non-Stoichiometric Compounds in Miyazaki, SSI in PyeongChang, ICE in Lausanne, EMA in Florida, and at 3 online conferences (Electroceramics, ECS PRIME, and ACERS EMA) due to COVID travel restrictions.
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| Current Status of Research Progress |
Current Status of Research Progress
3: Progress in research has been slightly delayed.
Reason
Although excellent progress has been made on many aspects of the project, surface analysis using low energy ion scattering (LEIS) has proven difficult due to equipment maintenance and data quality. As such, the research has pivoted to more tracer diffusion studies using secondary ion mass spectrometry (SIMS) and transmission electron microscopy (TEM). To ensure that progress is still being made, new avenues to characterise the films are being developed and a collaboration with the University of California, Irvine has been started where high-resolution vibrational electron-energy loss spectroscopy (VEELS) will be performed to carry out localised tracer diffusion in the TEM.
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| Strategy for Future Research Activity |
Further analysis of tracer diffusion profiles will be carried out using SIMS in the coming weeks and months. Further TEM analysis of thin films with different microstructures will be carried out in addition to those being performed at UC Irvine. A grant was applied for to support the collaboration with the University of California, Irvine submitted to the USA National Science Foundation (NSF), but was unsuccessful. The proposal is currently being modified and will be resubmitted.
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| Causes of Carryover |
The research expenditure will primarily be used for carrying out the remaining TEM analysis on samples to be compared with the SIMS tracer diffusion profiles.
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