実験報告書様式（一般利用課題・成果公開利用）（ ※本報告書は英語で記述してください。ただし、産業利用課題として採択されている方は日本語で記述していただいても結構です。 ）MLF Experimental Report

提出日 Date of Report
2011.06. 25

課題番号 Project No.

装置責任者 Name of responsible person

2010B0007

Takashi Kamiyama

実験課題名 Title of experiment

装置名 Name of Instrument/（BL No.）

Occupancy Site Analysis of Electrochemically Inserted Lithium in γ-Fe2O3

BL-08

実験責任者名 Name of principal investigator

実施日 Date of Experiment

Takeshi Yao

2010. 11. 12 13:00 ~ 2010. 11. 13 13:00

所属 Affiliation

2011. 03. 08 13:00 ~ 2011. 03. 09 13:00

Kyoto University
試料、実験方法、利用の結果得られた主なデータ、考察、結論等を、記述して下さい。（適宜、図表添付のこと）
Please report your samples, experimental method and results, discussion and conclusions. Please add figures andtables for better explanation.
1. 試料 Name of sample(s) and chemical formula, or compositions including physical form.
Name of sample : Lithium inserted iron oxide
Chemical formula : LiXFe2O3 (x=0 and 1.5)

2. 実験方法及び結果 （実験がうまくいかなかった場合、その理由を記述してください。）
Experimental method and results.

If you failed to conduct experiment as planned, please describe reasons.

FeCl2·4H2O is dissloved in a buffer solution of pH 6.2. The solution is stirred for 30 min at room temperature
under oxygen atmosphere. γ-FeOOH is obtained by collecting the precipitate using a vacuum filter and drying at
70 ℃. This precipitate is vacuum-dried for 72 h at 200 ℃ to obtain γ-Fe2O3.
Lithium are inserted electrochemically into synthesized nano γ-Fe2O3. Electrochemical measurement isperformed using an Ar-sealed three-electrode glass beaker cell. The working electrode is formed by mixing γFe2O3 as the active material, AB as a supplemental conductor, and PTFE (polytetrafluoroethylene) as an adhesive
agent at a ratio of 70:30:5 by weight. The working electrode samples are crimped to a nickel mesh as the current
collector. Li metal is used for the counter electrode and reference electrode. 1 mol dm-3 LiClO4/(EC+DME) (1:1v/v) is used for the electrolyte solution. The samples are discharged from the natural potential of approximately 3V (vs. Li/Li+) at a current density of 0.01 Ag-1. The amount of Li estimated by integrating the current is x= 1.5 interms of LiXFe2O3. After the required electrochemical conditions are attained, the circuits are opened
immediately. And the working electrode is detached from the glass beaker cell and set in a vanadium cell in an
argon gas system and this is used for neutron diffraction.
12. 実験方法及び結果（つづき） Experimental method and results (continued)
Due to limitation of measuring time, we made several samples with elapsed time after lithium insertion.
(Sample with elapsed time of 8, 30, 64, 100, and 300 hour after lithium insertion) Neutron powder diffraction ismeasured at room temperature for all specimens. The obtained neutron diffraction patterns are analyzed by theRietveld method.
Previously, we measured XRD and analyzed the structure of γ-Fe2O3 by the Rietveld method by using RIEVEC
program coded by T. Yao [1-3]. Fd3m are employed as the space group of the samples. For each of the 8a, 8b,16c, and 16d cation sites, the amount of iron are optimized. Peaks derived from the nickel collector and AB
observed in the patterns are also evaluated as background at the same time. In this case, contribution of lithiumwas ignored. The X-ray Rietveld analysis revealed that the iron occupancy of 8a site decreased and that of 16c
site increased with lithium insertion process and after lithium insertion, the iron occupancy of 8a site increased
and that of 16c site decreased gradually with time. It was considered that lithium was inserted at 8a site in theprocess of lithium insertion and after lithium insertion, lithium migrated from 8a site to 16c site. [3-10]
In this study, neutron diffraction pattern was analyzed similar to XRD analysis but including lithium foranalysis. For the sample before lithium insertion, obtained structure was very consistent with that of XRD
analysis. This is the first time for us to measure the sample by neutron diffraction. It is considered that theneutron diffraction measurement was well conducted for our sample. After lithium insertion, iron occupancy at
8a site decreased and that of 16c site increased, these are very similar to the result of XRD analysis, however
different from XRD analysis, iron occupancy at 16d site decreased. From XRD analysis, we estimated thatinserted lithium occupied 8a site and this was well shown by neutron diffraction analysis. On the contrary toXRD analysis, lithium occupancy at 8b site was indicated. This is a new information for the structure for lithium
inserted γ-Fe2O3, and we think it is necessary to make a more detail measurement and precise analysis.

Reference[1] T.Yao, T.Ito and T.Kokubo, J. Mater. Res., 10, p 1079-1082 (1995)[2] T.Yao, N.Ozawa, T.Aikawa and S.Yoshinaga, Solid State Ionics, 175, p 199-202 (2004)[3] S. Yamauchi, M. Hibino, T. Yao, Solid State Ionics, 191, 45 (2011)[4] S. Park, M. Oda, T. Yabutsuka, M. Hibino, T. Yao, The 2nd International Symposium Kyoto University Global
COE Program, Kyoto, Japan, p 44 (2010)[5] S.Park, M.Oda, T.Yabutsuka, M.Hibino and T.Yao, IRE2010, p 203-204 (2010)[6] M.Oda, S.Park, T.Yabutsuka, M.Hibino and T.Yao, J. Electrochem. Soc., CD Abst. 049 (2010)[7] S.Park, M.Oda, T.Yabutsuka, M.Hibino and T.Yao, The 51th battery symposium, p 172 (2010)[8] S.Park, M.Oda, T.Yao, The 78th Annual Meeting of Electrochemical Society of Japan, Abst. 2MO6 (2011)[9] S.Park, M.Oda, T.Yao, International Symposium on Advanced Energy Systems and Materials, Abst. 28 (2011)[10] S.Park, M. Oda, T.Yao, J. Electrochem. Soc., CD Abst. 042 (2011)2