Energy-dispersive X-ray diffraction study of liquid gallium under high pressure at elevated temperatures

Yagafarov, O.; Katayama, Yoshinori; Brazhkin, V. V.*; Lyapin, A. G.*; Saito, Hiroyuki

High Pressure Research, 33(1), p.191 - 195, 2013/01

https://doi.org/10.1080/08957959.2012.757311

Densified low-hygroscopic form of PO glass

Brazhkin, V. V.*; Akola, J.*; Katayama, Yoshinori; Kohara, Shinji*; Kondrin, M. V.*; Lyapin, A. G.*; Lyapin, S. G.*; Tricot, G.*; Yagafarov, O.

Journal of Materials Chemistry, 21(28), p.10442 - 10447, 2011/07

https://doi.org/10.1039/c1jm10889a

PO compound is an archetypical glass-forming oxide with a high hygroscopicity. We found that the quenching from the POmelt under ultrahigh pressures enables obtaining densified PO glasses with a residual densification up to 12% at normal conditions. These glasses have a low hygroscopicity and can exist under air conditions for several weeks. An examination of the structure of the new form of PO glass reveals a cardinal decrease of the volume of nanovoids in the glassy matrix.

Densified SiO glass study by RMC simulation using X-ray and neutron diffraction data

Yagafarov, O.; Kohara, Shinji*; Temleitner, L.*; Inamura, Yasuhiro; Katayama, Yoshinori

no journal, , 

Measurements of silica glass and water using a high-prssure diffractometer in J-PARC/MLF

Katayama, Yoshinori; Hattori, Takanori; Yagafarov, O.*; Saito, Hiroyuki; Sano, Asami; Suzuya, Kentaro; Chiba, Ayano*

no journal, , 

As the first high-pressure experiments on structurally disordered materials using a new high-pressure neutron diffractometer, PLANET, installed in J-PARC/MLF, measurements of silica glass were caried out. We compressed a sample in a ZrO cube using a six-axis press and measured diffraction at pressures of 0.1 MPa, 2.3, 5.5, 7.5 and 9.9 GPa at room temperature. The size of the sample was 4.6 mm in diameter and 6.7 mm in height. The size of the incident beam was 2.5 mm in width and 4.5 mm in height. The pressure was estimated from the applied load. Vanadium sample and empty cell were also measured for the correction of the diffraction intensity. Clean diffraction patterns without diffraction lines from surrounding materials were obtained thanks to the radial collimator system. Measurements on heavy water at room temperature, 100C and 200C at 0.8 GPa were also carried out. Significant temperature dependence of diffraction pattern was observed.

Feasibility study of neutron diffraction measurements of silica glass under high pressure

Katayama, Yoshinori; Yagafarov, O.; Machida, Akihiko; Hattori, Takanori; Sano, Asami; Komatsu, Kazuki*; Otomo, Toshiya*

no journal, , 

To test feasibility of neutron diffraction measurements of glass at high pressures up to several GPa, a sample of silica glass in a Paris-Edinburgh type high-pressure apparatus was measured at ambient conditions using a total scattering spectrometer, NOVA, at the Japan Proton Accelerator Complex (J-PARC). The sample has a shape of double convex lens, 6 mm in diameter, 4.4 mm in thickness. It was surrounded by a ring-shape gasket made of TiZr alloy and two anviles made of tungsten carbide. The incident neutron beam passed through a anvil and the diffracted beam passed through the gasket. The data acquisition time was about 20 hours. A vanadium sample and the empty gasket were also measured as references. A clear oscillation was observed in the intensity as a function of wave number.

The Current status of the J-PARC high-pressure neutron diffractometer PLANET & its application to silica glass

Hattori, Takanori; Sano, Asami; Inamura, Yasuhiro; Funakoshi, Kenichi*; Abe, Jun*; Machida, Shinichi*; Okazaki, Nobuo*; Katayama, Yoshinori; Yagafarov, O.*; Chiba, Ayano*

no journal, , 

SiO glass consists of SiO tetrahedra. This glass is easily densified by applying pressure, due to its relatively sparse network ring formed by the linkage of tetrhaera. The density increase amounts to 20% by room temperature compression to 8 GPa. This increase is, however, released after decompression because of insufficient structural relaxation. On the other hand, the heating at high pressures promotes the structural relaxation, resulting in permanent densification of 20% at most. The mechanism of this densification has been investigated so far, but the microscopic origin is still to be revealed. So, we performed in-situ high-pressure neutron experiments at newly constructed high-pressure neutron beamline PLANET in J-PARC. We will discuss the origin of the reversibility in the densification.

High-pressure neutron experiments on SiO glass using J-PARC high-pressure neutron diffractometer PLANET

Hattori, Takanori; Yagafarov, O.*; Katayama, Yoshinori; Sano, Asami; Saito, Hiroyuki; Chiba, Ayano*; Inamura, Yasuhiro; Suzuya, Kentaro; Otomo, Toshiya*

no journal, , 

SiO glass consists of SiO tetrahedra. This glass is easily densified by applying pressure, due to its relatively sparse network ring formed by the linkage of tetrahedra. The density increase amounts to 20% by room temperature compression to 8 GPa. This increase is, however, released after decompression because of insufficient structural relaxation. On the other hand, the heating at high pressures promotes the structural relaxation, resulting in permanent densification of 20% at most. The mechanism of this densification has been investigated so far, but the microscopic origin is still to be revealed. So, we performed in-situ high-pressure neutron experiments at newly constructed high-pressure neutron beamline PLANET in J-PARC. We will discuss the origin of the reversibility in the densification.

X-ray and neutron structural study on water under high pressure and high temperature

Katayama, Yoshinori; Hattori, Takanori; Saito, Hiroyuki; Sano, Asami; Suzuya, Kentaro; Yagafarov, O.*; Chiba, Ayano*; Otomo, Toshiya*

no journal, , 

Liquid water at ambient conditions has an ice-like, characteristic structure due to the hydrogen bonds between molecules. To study pressure and temperature dependence of the structure of water, we have carried out in-situ high-temperature high-pressure measurements on liquid water using synchrotron radiation at the SPring-8 and molecular dynamics simulations. The results revealed transformation from the ice-like structure to a simple-liquid-like structure. To investigate change in hydrogen bonds, neutron is an important probe. We carried out neutron diffraction measurements on heavy water at room temperature, 100C and 200C at 0.8 GPa using newly-built high-pressure diffractometer, PLANET, at J-PARC/MLF. Significant temperature dependence of diffraction pattern was observed.

X-ray and neutron structural study on water under high pressure and high temperature, 2

Katayama, Yoshinori; Hattori, Takanori; Yagafarov, O.*; Saito, Hiroyuki; Sano, Asami; Suzuya, Kentaro; Chiba, Ayano*; Otomo, Toshiya*

no journal, , 

Liquid water at ambient conditions has an ice-like, characteristic structure due to the hydrogen bonds between molecules. To study pressure and temperature dependence of the structure of water, we have carried out in-situ high-temperature high-pressure measurements on liquid water by in-situ synchrtorn X-ray diffraction experiments at the SPring-8 and molecular dynamics simulations. The results revealed transformation from the ice-like structure to a simple-liquid-like structure. To investigate change in hydrogen bonds, neutron is an important probe. We carried out neturon diffraction measurements on heavy water at 100C and 200C at 2 GPa using high-pressure diffractometer, PLANET, at J-PARC/MLF. Significant temperature dependence of width of first peak in diffraction pattern, which is similar to that observed in the previous neutron diffraction experiments at 0.8 GPa.

High-pressure neutron study on silica glass at J-PARC high-pressure neutron diffractometer PLANET

Hattori, Takanori; Yagafarov, O.*; Katayama, Yoshinori; Chiba, Ayano*; Sano, Asami; Inamura, Yasuhiro; Otomo, Toshiya*; Matsuzaki, Yuki*; Shimojo, Fuyuki*

no journal, , 

PLANET is the beamline dedicated for the high-pressure experiments. The operation has been started at JFY 2013, and now many users are coming to use. In this talk, we introduce the current state of the PLANET and the example of the structure analysis of disordered materials. PLANET adopted the double staged compression system of the multi anvil 6-6, and enables the data collation at 10 GPa and 2000 K. To extend accessible PT range, we newly introduce another compression system of multi-anvil 6-8, and succeeded in generating 16 GPa and 1273 K. In addition, the PLANET is designed so that we can analyze the structure of liquid under pressure. In the analysis, the program for liquid analysis developed at BL21 NOVA is used. Here, we briefly introduce the reliability of the results and the pressure evolution of the silica glass.