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
2011/07/04

課題番号 Project No. 2010B0075

装置責任者 Name of responsible person

実験課題名 Title of experiment:

Stefanus Harjo

Bonding and disordering transformations of layered magnesium

装置名 Name of Instrument/（BL No.）hydroxide at pressure

BL19 TAKUMI

実験責任者名 Name of principal investigator

実施日 Date of Experiment

Takuo Okuchi

2010/12/16 - 2010/12/17

所属 Affiliation
Okayama 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.
Deuterated magnesium hydroxide (brucite): Mg(OD)2
Deuterated glyceline: C3D5(OD)3

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.

The Mg(OD)2 powder sample was synthesized at250ºC and 4 MPa by reacting MgO powder and D2O inan autoclave for a week. No significant OH residual
peak was observed in its IR spectra. Our newlydeveloped opposed-anvil high-pressure cell is shown inthe figure. Mg(OD)2 powder of ~4 mm3 volume (9 mg)
was enclosed into the cell along with deutereatedglyceline, which works as liquid pressure medium toalleviate uniaxial stress applied to the sample. It wasslowly compressed by fastening the six screws, andthen annealed at 80 oC for 1h. This high pressure cell
was designed to generate 10 GPa for 3 mm3 volume
and 20~30 GPa for 1mm3 volume.
12. 実験方法及び結果（つづき） Experimental method and results (continued)
At this time, we have successfully generated up to 8 GPa pressures and took neutron diffraction patterns ofmoderate quality. An observed pattern at 5 GPa is shown below (d-value shown in angstrom). Spurious peaks
mainly coming from two anvils directly contacting with the sample; these are made of NPD(nano-polycrystalline diamond) and SD (sintered diamond), giving strong diffraction pekas of powdereddiamond. These peaks have different d-values from the sample which were removed from the figure. All fivepeaks in the figure, including the most strong one at 2.3 A for 011 diffraction, were coming from the Mg(OD)2.
These were strong enough to determine the lattice constant variations at high pressure by Le Bail fit, althoughwere still marginal to conduct a Rietveld analysis to determine the deuteron positions.

We have installed a microscope-based ruby fluorescence system at TAKUMI. Using this system, sample
pressures were swiftly measured by optical ruby fluorescence technique through the transparent NPD anvil(Note: this system has now moved to the cabin close to BL11). We observed that the intensities of spurious
diffraction were significantly reduced by the following procedures: (i) Shielding of neutrons using thecombination of cadmium foil, hBN (boron nitride) tube collimator, boron rubber plate, and sinterd 6LiF plate
collimator. We have prepared a number of hBN collimators with different inner diameters to best-fit the sample
size. We have also prepared sintered 6LiF collimators with different inner diameters for use at the beam entrance
to reduce the gamma-ray background to scintillation detectors. (ii) Fine tuning of neutron focusing device
designed for TAKUMI. It works not only to increase the beam intensity at the sample position but also to reducethe background.
We have prepared for our second beamtime scheduled on March 14 to 15 to conduct the experiments at higher
pressures than 10 GPa, for a reduced sample volume at ~1 mm3. We were also ready to increase the pressure
on-site to obtain the results at multiple pressures, all of which would be the first results of neutron diffraction at>10 GPa for this sample. However, the earthquake had made it impossible. We are expecting that after therecovelry of TAKUMI, we will continue the proposed experiments to complete the scientific mission described.

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