2013 Fiscal Year Annual Research Report
| Project/Area Number |
13F03751
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| Research Institution | Osaka University |
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Principal Investigator |
吉田 博 大阪大学, 基礎工学研究科, 教授
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| Co-Investigator(Kenkyū-buntansha) |
MOHAMAND HUSSEIN NASEF Al Assadi 大阪大学, 基礎工学研究科, 外国人特別研究員
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| Keywords | Density Functional / Thermoelectrics / Phonon modes |
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| Research Abstract |
I joint Osaka University on 25th of November 2013. In the past four month my research was focused on studying the thermoelectric properties of Ba doped and Sb doped sodium cobaltate along with hafnium nickel tin based half Heuser alloys. The objective of the research is to establish the upper limit of thermoelectric performance by using doping technology in bulk systems. This research was conducted using VASP ab initio package on Australian Computational Infrastructure.
The applied research methodology included density functional based defect/dopant formation energy calculations to reveal the favourite doping concentration, lattice site, charge state for any given dopants which is known as energetics calculations. After establishing dopants' energetic, first-principles molecular dynamics for~15 ps at various temperatures are calculated to establish average atomic displacement in form of 3 X 3 matrices. The generated insight will then determine the maximum reduction in thermal conductivity in investigated systems. Since obtaining full experimental understanding of thermal conductivity for different phonon modes are increasingly difficult, we anticipate the generated computational results will guide the future experimental efforts. So far the energetics of Ba and Sb dopants in sodium cobaltate has been successfully calculated.
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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
Clarifying the energetics of Sb in sodium cobaltate (NaxCo02). Sb can take multiple charge states varying from neutral to 5+. That combined with four possible incorporation sites in NaxCo02 will generate a complex combination of configurations. To add to the complexity Na content of sodium cobaltate is also a variable. We have been able to clarify the interplay between these factors that influence Sb configuration in sodium cobaltate. We will submit a manuscript describing our findings in the coming month.
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| Strategy for Future Research Activity |
Future work includes the calculations regarding the ab initio molecular dynamics of Sb and Ba doped systems.
These calculations will be very demanding as for each configuration few temperatures should be considered to extract meaningful results. Further more, I will conduct electronic transport calculations for complement the thermal transport outcomes with the electronic transport data. Therefore we can predict the enhancement in the ZT or figure of merit of the investigated system.
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