Development of a diamond anvil cell for high-pressure neutron diffraction experiments

Machida, Shinichi*; Hattori, Takanori; Nakano, Satoshi*; Sano, Asami; Funakoshi, Kenichi*; Abe, Jun*

Koatsuryoku No Kagaku To Gijutsu, 34(3), p.134 - 142, 2024/09

https://doi.org/10.4131/jshpreview.34.134

A diamond anvil cell (DAC) for high-pressure neutron diffraction experiments has been developed at the PLANET beamline, Materials and Life Science Experimental Facility, in J-PARC. The conically supported diamond anvils were used for high-pressure generation. We succeeded in obtaining the neutron data for DO ice up to 69.4 GPa. In addition, the gasket materials suitable for the neutron diffraction measurements were investigated. 11 kinds of alloys were tested and SUS304, Inconel718 and M2052 (73Mn-20Cu-5Ni-2Fe, at%) alloys showed excellent performance. Especially, M2052 null-matrix alloy has proven to be useful for neutron diffraction experiments where the beam inevitably hits the gasket. We then obtained refinable neutron diffraction profiles in Rietveld analysis from DO ice at least up to 43.3 GPa.

Phase transformation and equation of state in Ti-45Al alloy under high pressure

Li, X.*; Zhu, R.*; Xin, J.*; Luo, M.*; Shang, S.-L.*; Liu, Z.-K.*; Yin, C.*; Funakoshi, Kenichi*; Dippenaar, R. J.*; Higo, Yuji*; et al.

CALPHAD; Computer Coupling of Phase Diagrams and Thermochemistry, 84, p.102641_1 - 102641_6, 2024/03

https://doi.org/10.1016/j.calphad.2023.102641

Structure of basaltic glass at pressures up to 18 GPa

Ohashi, Tomonori*; Sakamaki, Tatsuya*; Funakoshi, Kenichi*; Hattori, Takanori; Hisano, Naoki*; Abe, Jun*; Suzuki, Akio*

American Mineralogist, 107(3), p.325 - 335, 2022/03

https://doi.org/10.2138/am-2021-7742

The basaltic glass structure were investigated to 18 GPa using in situ X-ray and neutron diffraction. The O-O coordination number (CN) starts to rise with maintaining the mean O-O distance (r) above 2-4 GPa, and then CN stops increasing and r begins to shrink along with the increase in the Al-O coordination number (CN) above 9 GPa. This is interpreted by the change in the contraction mechanism from tetrahedral network bending to oxygen packing ratio increase via the CN increase. The oxygen packing fraction exceeds the value for dense random packing, suggesting that the oxygen-packing hypothesis cannot account for the pressure-induced structural transformations of silica and silicate glasses. The CN increase at 2-4 GPa reflects the elastic softening of silicate glass, which may causes anomalous elastic moduli of basaltic glass at 2 GPa.

High-pressure and high-temperature neutron-diffraction experiments using Kawai-type multi-anvil assemblies

Sano, Asami; Kakizawa, Sho*; Shito, Chikara*; Hattori, Takanori; Machida, Shinichi*; Abe, Jun*; Funakoshi, Kenichi*; Kagi, Hiroyuki*

High Pressure Research, 41(1), p.65 - 74, 2021/03

https://doi.org/10.1080/08957959.2020.1867723

We applied Kawai-type multi-anvil assemblies (MA6-8) for time-of-flight neutron-diffraction experiments to achieve high pressures and high temperatures simultaneously. To achieve sufficient signal intensities, the angular access to the sample was enlarged using slits and tapers on the first-stage anvils. Using SiC-binder sintered diamond for the second-stage anvils that transmits neutrons, sufficient signal intensities were achieved at a high-pressure of 23.1 GPa. A high-temperature experiment was also conducted at 16.2 GPa and 973 K, validating the use of tungsten carbide for the second-stage anvils. The present study reveals the capability of the MA6-8 cells in neutron-diffraction experiments to attain pressures and temperatures beyond the limits of the conventional MA6-6 cells used in the high-pressure neutron diffractometer PLANET at the MLF, J-PARC.

Practical effects of pressure-transmitting media on neutron diffraction experiments using Paris-Edinburgh presses

Hattori, Takanori; Sano, Asami; Machida, Shinichi*; Ouchi, Keiichi*; Kira, Hiroshi*; Abe, Jun*; Funakoshi, Kenichi*

High Pressure Research, 40(3), p.325 - 338, 2020/09

https://doi.org/10.1080/08957959.2020.1782899

To understand the practical effects of pressure-transmitting media (PTM) on neutron diffraction using Paris-Edinburgh presses, diffraction patterns of MgO were collected to approximately 20 GPa using PTMs of Pb, AgCl, 4:1 methano-ethanol (ME) mixture with and without heating, N, and Ar. Hydrostaticity in the sample chamber estimated from the MgO 220 peak width improves in the order of Pb, AgCl, Ar, ME mixture, N, and the heated ME mixture. Unlike previous results using a diamond anvil cell, the unheated ME mixture is superior to Ar even after freezing, probably due to the cup on the anvil face. Considering these results and the sizable coherent scattering of Ne, which would show good hydrostaticity, we conclude that the ME mixture (preferably the heated one) is the best PTM in neutron experiments up to 20 GPa, while Ar can be substituted when a sample is reactive to alcohols.

Crystal and magnetic structures of double hexagonal close-packed iron deuteride

Saito, Hiroyuki*; Machida, Akihiko*; Iizuka, Riko*; Hattori, Takanori; Sano, Asami; Funakoshi, Kenichi*; Sato, Toyoto*; Orimo, Shinichi*; Aoki, Katsutoshi*

Scientific Reports (Internet), 10, p.9934_1 - 9934_8, 2020/06

https://doi.org/10.1038/s41598-020-66669-4

Neutron powder diffraction profiles were collected for iron deuteride (FeDx) while the temperature decreased from 1023 to 300 K for a pressure range of 4-6 GPa. The ' deuteride with a double hexagonal close-packed (dhcp) structure, which coexisted with other stable or metastable deutrides at each temperature and pressure condition, formed solid solutions with a composition of FeD at 673 K and 6.1 GPa and FeD at 603 K and 4.8 GPa. Upon stepwise cooling to 300 K, the D-content x increased to a stoichiometric value of 1.0 to form monodeuteride FeD. In the dhcp FeD at 300 K and 4.2 GPa, dissolved D atoms fully occupied the octahedral interstitial sites, slightly displaced from the octahedral centers in the dhcp metal lattice, and the dhcp sequence of close-packed Fe planes contained hcp-stacking faults at 12%. Magnetic moments with 2.11 0.06 B/Fe-atom aligned ferromagnetically in parallel on the Fe planes.

Hexagonal close-packed iron hydride behind the conventional phase diagram

Machida, Akihiko*; Saito, Hiroyuki*; Hattori, Takanori; Sano, Asami; Funakoshi, Kenichi*; Sato, Toyoto*; Orimo, Shinichi*; Aoki, Katsutoshi*

Scientific Reports (Internet), 9(1), p.12290_1 - 12290_9, 2019/08

https://doi.org/10.1038/s41598-019-48817-7

Hexagonal close-packed iron hydride, hcp FeHx, is absent from the conventional phase diagram of the Fe-H system, although hcp metallic Fe exists stably over extensive temperature () and pressure () conditions, including those corresponding to the Earth's inner core. X-ray and neutron diffraction measurements at temperatures ranging from 298 to 1073 K and H pressures ranging from 4 to 7 GPa revealed that the hcp hydride was formed for FeH compositions when . Hydrogen atoms occupied the octahedral interstitial sites of the host metal lattice both partially and randomly. The hcp hydride exhibited a H-induced volume expansion of 2.48(5) /H-atom, which was larger than that of the face-centered cubic (fcc) hydride. The hcp hydride showed an increase in with , whereas the fcc hydride showed a corresponding decrease. The present study provides guidance for further investigations of the Fe-H system over an extensive -- region.

What can we do with the high-pressure neutron diffractometer PLANET?

Hattori, Takanori; Sano, Asami; Machida, Shinichi*; Abe, Jun*; Funakoshi, Kenichi*; Okazaki, Nobuo*

Nihon Kessho Gakkai-Shi, 59(6), p.301 - 308, 2017/12

https://doi.org/10.5940/jcrsj.59.301

PLANET is a neutron beamline dedicated to high-pressure experiments. Combining the intense neutron source of J-PARC and high-pressure devices designed for time-of-flight powder neutron diffraction enables precise structure analysis of crystal, liquid and amorphous solids over wide pressure and temperature region of 0-20 GPa and 77-2000K. This beamline is effective for various studies in geophysics, planetary science, physics and chemistry. This paper overviews the beamline and introduces recent results obtained at PLANET.

Hydrostatic compression behavior and high-pressure stabilized -phase in -based titanium aluminide intermetallics

Liss, K.-D.*; Funakoshi, Kenichi*; Dippenaar, R. J.*; Higo, Yuji*; Shiro, Ayumi*; Reid, M.*; Suzuki, Hiroshi; Shobu, Takahisa; Akita, Koichi

Metals, 6(7), p.165_1 - 165_22, 2016/07

https://doi.org/10.3390/met6070165

Titanium aluminides find application in modern light-weight, high-temperature turbines, such as aircraft engines, but suffer from poor plasticity during manufacturing and processing. Huge forging presses enable materials processing in the 10 GPa range and hence, it is necessary to investigate the phase-diagrams of candidate materials under these extreme conditions. Here we report on an in-situ synchrotron X-ray diffraction study in a large-volume-press of a modern ( + ) two-phase material, Ti-45Al-7.5Nb-0.25C, under pressures up to 9.6 GPa and temperatures up to 1686 K. At room temperature, the volume response to pressure is accommodated by the transformation rather than volumetric strain, expressed by apparently high bulk moduli of both constituent phases. Crystallographic aspects, specifically lattice strain and atomic order are discussed in detail. It is interesting to note that this transformation takes place despite an increase in atomic volume, which is due to the high ordering energy of . Upon heating under high pressure, both the eutectoid and -solvus transition temperatures are elevated, and a third, cubic -phase is stabilized above 1350 K. Earlier research has shown that this -phase is very ductile during plastic deformation, essential in near-conventional forging processes. Here, we were able to identify an ideal processing window for near-conventional forging, while the presence of the detrimental -phase is not present under operating conditions. Novel processing routes can be defined from these findings.

Ponded melt at the boundary between the lithosphere and asthenosphere

Sakamaki, Tatsuya*; Suzuki, Akio*; Otani, Eiji*; Terasaki, Hidenori*; Urakawa, Satoru*; Katayama, Yoshinori; Funakoshi, Kenichi*; Wang, Y.*; Hernlund, J. W.*; Ballmer, M. D.*

Nature Geoscience, 6(12), p.1041 - 1044, 2013/12

https://doi.org/10.1038/ngeo1982

The bounday between Earth's rigid lighosphere and the underlying, ductile ashenosphere is marked by a distinct siseismic discontinuity. We measure the density, viscosity and structure of basaltic magmas using high-pressure and high-temperature experiments and in situ X-ray analysis under pressure of up to 5.5 GPa. We find that the magmas rapidly become denser with increasing presure and show a viscosity minimum near 4 GPa. Magma mobility determined by the density and viscosity data exhibits a peak at pressures corresponding to depths of 120-150 km, within the asthenosphere. The diminishing mobility of magma in Earth's asthenosphere as the mlets ascend could lead to excessive melt accumulation at depths of 80-100 km, at the lithosphere-asthenosphere boundary. It is concluded that the observed seismic discontinuity at the lithosphere-asthenosphere boundary records this accumulation of melt.