2018 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 – 2020-03-31
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| Keywords | oxides / thin films / segregation / surfaces / grain boundaries |
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| Outline of Annual Research Achievements |
Several series of rare-earth substituted ceria has been synthesised and characterised using X-ray diffraction. The samples have been processed into pellets and polished to create well-defined surfaces for segregation analysis.
A lanthanum strontium manganite target has been fabricated for pulsed laser deposition, and films on strontium titanite have been grown and characterised by X-ray diffraction ensuring high-quality growth. Bicrystal substrates of strontium titanite and yttria-stabilised zirconia of various miscut angles have been purchased for the fabrication of well-defined grain boundaries.
Oral presentations have been given at the ECS conference in Seattle, E-MRS conference at Strasbourg, Electroceramics conference at Hassalt, and Non-Stoichiometric Compounds conference in Miyazaki.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
We have made excellent progress fabricating samples to study the thermodynamics of surface segregation. There have been issues with the measuring the surface segregation due to the low-energy ion scattering equipment being under maintenance, but that has recently been repaired and analysis of the segregation effects will soon be made.
There have been further issues with the heater on the pulsed laser deposition equipment, where the substrate is not reaching the temperature it should. This is currently being solved and will ensure that high quality epitaxial films of lanthanum strontium manganite can be grown on bi-crystals.
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| Strategy for Future Research Activity |
In the next weeks, surface analysis will be carried out on the well-defined surfaces of rare-earth substituted ceria solid state solutions. This will allow me to assess the driving forces for segregation in these materials, giving valuable insights into understanding segregation effects in oxide materials for high temperature electrochemical applications.
High-quality epitaxial films of lanthanum strontium manganite films on bi-crystals will soon be fabricated and sent to Vienna, Austria where Dr. Tobias Huber and Prof. Juergan Fleig will carry out tracer diffusion measurements to assess the effects of grain boundary misorientation on the diffusion rate of oxygen. The samples will then return to Kyushu University for advanced transmission electron microscopy analysis.
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| Causes of Carryover |
Due to the issues with the low energy ion scattering and pulsed laser deposition equipment, these equipment could not be used as much as planned resulting in lower equipment charges.
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