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。 ）提出日 Date of Report

MLF Experimental Report

2012. 5. 23

課題番号 Project No.

装置責任者 Name of responsible person

2012B0046

Toru Ishigaki

実験課題名 Title of experiment

装置名 Name of Instrument/（BL No.）

Detailed

CrystalStructuresofNa5/6[Li1/4Mn3/4]O2

asiMATERIA/BL-20

High-Energy Manganese-Based Electrode Materials for Li/Na

実施日 Date of Experiment

Batteries

2012.11.23-2012.11.24

実験責任者名 Name of principal investigator2013.3.5-2013.3.6

Shinichi Komaba
所属 AffiliationTokyo University of Science
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.
1. Sodium manganese oxide containing lithium: P2-type layered Na5/6[Li1/4Mn3/4]O2 with a space group ofP63/mmc.
2. Sodium manganese oxide containing lithium: P2-type layered Na2/3[Li1/6Mn5/6]O2 with a space group ofP63/mmc.
3. Lithium-rich manganese oxide: O2-type layered Lix[Li1/4Mn3/4]O2 with a space group of P63/mc.

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.
Experimental method:

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

Neutron diffraction data of samples were collected at room temperature using atime-of-flight (TOF) neutron powder diffractometer at iMATERIA (BL20).

The samples were put in acylindrical vanadium cell (6 mm in inner diameter and more than 30 mm in height), which was sealed withindium metal in a helium-filled glove box. The neutron diffraction data were analyzed by the Rietveld method
using the Rietveld analysis program, Z-Rietveld that was developed in J-PARC.
Results: Figure 1 shows a Rietveld refinement pattern of Na5/6[Li1/4Mn3/4]O2. The neutron diffraction pattern
can be indexed with a space group of P63/mmc. Na5/6[Li1/4Mn3/4]O2 consists of two [Li1/4Mn3/4]O2 layers thatare stacked alternately along c-axis direction. Na ions are located at two different prismatic sites sandwiched inbetween the [Li1/4Mn3/4]O2 layers. Supperlattice peaks were not observed on the neutron diffraction pattern
because the difference of scatter length between lithium and manganese is quite small. Structural parametersrefined by the Rietveld method for Na5/6[Li1/4Mn3/4]O2 are summarized in Table 1. Although occupancy oflithium and oxygen was refined, deficiency at lithium and oxygen sites was not evidenced. The refinement

12. 実験方法及び結果（つづき） Experimental method and results (continued)
results clearly indicate a good agreement between the structural model and observed pattern.

Isotropic atomic

displacement parameters for the sodium sites that are located at two different sites were also refined. Relatively
high displacement parameters are found as shown in Table 1, which is a consistent with the X-ray Rietveld
refinement on a synchrotron X-ray diffraction pattern. Now, detailed analyses by Fourier synthesis and/or
MEM analysis on the neutron diffraction data of the samples, including a Na+/Li+-exchanged product, are inprogress.

Fig. 1.

Rietveld refinement on the neutron diffraction data of Na5/6[Li1/4Mn3/4]O2: A comparison of observed(crosses) and calculated (black line) patterns with its difference (blue line). The short vertical green lines
indicate the peak positions of all the possible Bragg reflections.
Table 1. Structural parameters obtained by the Rietveld refinement on the neutron diffraction data of
Na5/6[Li1/4Mn3/4]O2.

Unit cell: P63/mmc (194); a = 2.8711(3) Å, c = 11.028(15) Å; Rwp = 8.00 %, Rp =6.21 %, Re = 1.24, RB = 4.86 %, RF = 6.74, S2 = 4.15.
AtomWyckoff positionsxyz

OccupancyBNa12b00

1/4

0.33

5.395(18)

Na2

2d

1/3

2/3

3/4

0.50

2.77(2)

Li

2a000

0.24

0.21(2)Mn

2a0000.76= B(Li)

O

4f

1/3

2/3

0.093(2)1.000(6)0.679(11)2