2006 Fiscal Year Final Research Report Summary
Diffusion studies in Li ionic conductors using short-lived radioactive nuclear beam of ^8Li
| Project/Area Number |
16360317
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Physical properties of metals
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| Research Institution | High Energy Accelerator Research Organization |
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Principal Investigator |
JEONG Sun-Chan High Energy Accelerator Research Organization, Institute of Particle and Nuclear Studies, Associate Professor, 素粒子原子核研究所, 助教授 (00262105)
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| Co-Investigator(Kenkyū-buntansha) |
KATAYAMA Ichiro High Energy Accelerator Research Organization, Institute of Particle and Nuclear Studies, Professor, 素粒子原子核研究所, 名誉教授 (30028237)
ISHIYAMA Hironobu High Energy Accelerator Research Organization, Institute of Particle and Nuclear Studies, Research Associate, 素粒子原子核研究所, 助手 (50321534)
WATANABE Yutaka High Energy Accelerator Research Organization, Institute of Particle and Nuclear Studies, Research Associate, 素粒子原子核研究所, 助手 (50353363)
ICHIKAWA Shinichi Japan Atomic Energy Agency, Advanced Basic Research Center, Head Researcher, 先端基礎研究センター, 研究主幹 (20343907)
YAHAGI Masato Aomori University, Dep. of Engineering, Professor, 工学部電子システム工学部, 教授 (20244890)
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| Project Period (FY) |
2004 – 2006
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| Keywords | radioactive diffusion tracer / Li ionic conductor / diffusion coefficient / complex defects / order-disorder transition of Li vacancy / 原子空孔の規則-不規則変態 / 固体材料界面の拡散抵抗 |
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| Research Abstract |
In this study, we have performed a systematic measurement of the diffusion coefficients of Li in solid Li ionic conductors by using the short-lived radioactive diffusion tracer of ^8Li (T_<1/2>=0.84s).
The diffusion coefficients in a typical Li ionic conductor of LiGa, were investigated in detail. With increasing Li contents in the β phase of LiGa (β-LiGa : 44〜54 at. %Li), the diffusion coefficients increase to the maximum around the stoichiometric composition and then decrease. This observation is very much different from that in β-LiAl and LiIn, which are iso-structural with the β-LiGa. Because of the relatively large concentration of Li vacancy in the Li deficient β-LiGa, a complex defect (a pair of Li vacancies) seems to be formed and operate to quench the Li diffusion. In addition, for the Li deficient β-LiGa, the order-disorder transition of Li vacancies was first observed in terms of Li diffusion. Below the transition temperature, a sudden decrease in the diffusion coefficients was observed, well demonstrating that the Li vacancies operating as carriers of the Li by exchange in Li sublatttices should be in an ordered state in lower temperature and that the resultant Li diffusion becomes slow as compared to that in higher temperature.
During the period of this study, we have also performed the development of the tracer beam of ^8Li in terms of the intensity and quality (energy spread of the beam) as well as of the detection system. As a result, the present method could be applied as a tool for analyzing (evaluating) the properties of the as-developed Li batteries under the presence of electrical potential, which has been generally performed by various electrochemical methods.
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