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
2015/3/6

課題番号 Project No. 2014A0329

装置責任者 Name of responsible person

実験課題名 Title of experimentToshiya Otomo

Crystal structure analyses for new hydrogen storage materials

装置名 Name of Instrument/（BL No.）

when absorbing/desorbing hydrogen

NOVA/BL21

実験責任者名 Name of principal investigator

実施日 Date of Experiment
2014/6/10-13, 11/21-23

Hiroshi NOZAKI
所属 Affiliation
Toyota Central R&D Labs., Inc.

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.
MH1: TiMn1.5
MH2: TiMn1.3Cr0.2
MOF-1: C12H12CuN2O4

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.

1. Metal hydride
The samples, TiMn1.5 (with large hysteresis) and TiMn1.3Cr0.2 (with small hysteresis), were prepared by heattreatment (1200°C 4 hours in argon atmosphere) after pure metals were alloyed with arc melting method. The
in-situ neutron diffraction (ND) measurements were performed by high intensity total scattering diffractometer(NOVA) equipped pressure-composition (P-C) isothermal measuring apparatus using deuterium gas.
Hysteresis phenomenon, which absorption and desorption pressures are different, appears in many hydrogenstorage alloys. In the practical use of hydrogen storage alloys, the development of small hysteresis alloys is oneof the important issues because wide range pressure control is needed in large hysteresis alloys. It is known thatthe substitution of Mn by Cr reduces the hysteresis in Ti-Mn alloys. However, the mechanism of hysteresis
reduction in hydrogen storage alloys is not clarified sufficiently. As compared with X-ray diffraction, ND
intensity for hydrogen atom is very high than that for metal atom. Therefore, the structural changes in hydrogen
absorption-desorption process has been studied by in-situ ND measurement in order to clarify the mechanism ofhysteresis phenomenon.

12. 実験方法及び結果（つづき） Experimental method and results (continued)
Figure 1 shows the result of P-C isothermal measurement of
the TiMn1.5 sample. Figure 2 shows the ND patterns at eachpoint on the P-C isothermal curve. In the hydrogen absorption
process, the diffraction peak intensity of hydrogen-poor Lavesphase (α-phase, TiMn1.5Dx x~0.5) decreases and that ofhydrogen-rich Laves phase (β-phase, TiMn1.5Dx x~2.0) increases
according to absorption of hydrogen. The reverse change occurs
in the hydrogen desorption process. The peaks of each phaseshift depending on hydrogen content. In future, the crystal
structural changes (the site position and occupancy of deuteriummainly) in the absorption and desorption process, will be studied
by Rietveld analysis.
2. Metal-organic framework material
The C12H12CuN2O4 single crystals, which belongs toFig.1 Pressure composition isothermal curve of theTiMn1.5 sample in neutron diffraction measurement.

metal-organic framework (MOF) [1], was synthesized by aself-organization from a mixture of Cu(HCO2)2·4H2O [2] andC5H5N. Then, the powder sample was prepared by crushing thesingle crystals. The powder sample was filled into the cylindricalsample holder made of sapphire. The in-situ ND patterns wererecorded on NOVA under D2 gas atmosphere.

The ND patterns

under vacuum and 8 MPa of D2 pressure are shown in Fig. 3
together with the simulated pattern using the crystallographic
parameters based on the ref. [1]. There are several unknown
diffraction peaks in the ND patterns. This means that the MOF
sample was probably decomposed before ND measurement.
65 46040Intensity (arb. units)

20

32CD4xDx
C12H1212CuN
CuN
2O12H24O(a) Vacuum

1.5

1.0

0.8

x = 0, vac(#10643)

unknown

the-202060

20andphases complicates040

Mixture of MOF(b) D2, 8MPa

x = 9.3, 8.0 MPa D2(#10647)

certainFig.2 Neutron diffraction patterns of the TiMn1.5
sample measured at each stage of Fig.1.

discussion at least at the present stage. We speculate that the MOF
sample was decomposed by absorbing water in air after crashing0the single crystals or by evacuating the inner-space of the sample-20(c) simulation

holder before pressurizing with D2 gas. As an alternative effort, wehave to convey the sample as synthesized, and crash it just before
measuring the ND pattern if needed.

Fig. 3 ND patterns under vacuum and D2[References]pressure of 8 MPa with the simulated [1] T. Takami et al., APL Materials 2, 096104 (2014).
[2] H. Kiriyama, Bull. Chem. Soc. Jpn. 35, 1199 (1962).
pattern.

2