JOPSS - Search Results

Journal Articles

The Disordered 3-dimensional structure visualized by a combination of high-energy synchrotron X-rays and computer simulations

Kohara, Shinji*; Oishi, Yasuo*; Takata, Masaki*; Yoneda, Yasuhiro; Suzuya, Kentaro

Nihon Kessho Gakkai-Shi, 47(2), p.123 - 129, 2005/04

https://doi.org/10.5940/jcrsj.47.123

The use of high-energy (E 50 keV) X-rays from SPring-8 allows us to perform X-ray diffraction experiments on disordered materials with the following advantages: high resolution in real space due to the wide range of scattering vector, small correction terms (particularly the absorption correction), and fast diffraction measurement with small amount of samples. Recently, high-energy X-ray diffraction data have been combined with neutron diffraction data from a pulsed neutron source to provide more detailed and reliable structural information than has hitherto been available. Furthermore, the use of reverse Monte Carlo modelling and PDF (pair distribution function) simulation based on high-energy X-ray diffraction data have succeeded in illustrating 3-dimensional structure of disordered materials and disorder in crystalline materials.

Journal Articles

Unusual structure in vitreous forsterite synthesized by an aero-acoustic levitation technique

Kohara, Shinji*; Suzuya, Kentaro; Takeuchi, Ken*

Nihon Maikurogurabiti Oyo Gakkai-Shi, 22(2), p.100 - 104, 2005/04

Forsterite Mg $_{2}$ SiO $_{4}$ exhibits an orthorhombic structure consisted of two kinds of MgO $_{6}$ octahedra. Given only 33.3 mol% of SiO $_{2}$ in the material, the SiO $_{4}$ tetrahedra are isolated within the framework, sharing the O-O bonds with the common edges of the MgO $_{6}$ octahedra. If forsterite can be vitrified, an interesting question concerning the glass structure arises because there is insufficient glass forming SiO $_{2}$ to establish the corner-sharing SiO $_{4}$ tetrahedral network needed in conventional silicate glasses. A bulk Mg $_{2}$ SiO $_{4}$ glass was synthesized using an aero-acoustic levitation technique and to determine the short- to intermediate-range structure by a combined high-energy X-ray and neutron diffraction and reverse Monte Carlo computer simulation. Interestingly, we found that the role of network former is largely taken on by corner- and edge-sharing ionic magnesium species that adopt 4-, 5- and 6-coordination with oxygen.

Journal Articles

High-energy X-ray diffraction studies of short- and intermediate-range structure in oxide glasses

Suzuya, Kentaro; Kohara, Shinji*

Materia, 41(3), p.206 - 215, 2002/03

http://ci.nii.ac.jp/naid/10008836947

With the arrival of the latest generation of synchrotron sources and the introduction of advanced insertion devices, the high-energy (E 30 keV) X-ray diffraction technique has become feasible, leading to new approaches in the quantitative study of the structure of disordered materials. Recently, the high-energy X-ray diffraction data have been combined with neutron diffraction data from a pulsed source to provide more detailed and reliable structural information than that hitherto available. We have developed a two-axis diffractometer for glass, liquid and amorphous materials at the SPring-8 high-energy X-ray diffraction beamline BL04B2. Furthermore, we have succeeded to analyze the intermediate-range order of network forming glasses, SiO $_{2}$ , B $_{2}$ O $_{3}$ , and GeO $_{2}$ by the reverse Monte Carlo (RMC) modelling technique with special focused on the ring structures using both high-energy X-ray and neutron diffraction data.

Journal Articles

Neutron diffraction measurements of the structure of an orthosilicate glass: Mg $_{2}$ SiO $_{4}$

Weber, J. K. R.*; Tangeman, J. A.*; Key, T. S.*; Loong, C.-K.*; Takeuchi, Ken*; Suzuya, Kentaro

Physics and Chemistry of Glasses, Vol.43C 2002, p.68 - 70, 2002/00

The structure of olivine-composition glasses is of considerable interest in both geology and glass-science. Olivine is one of the most common minerals in the Earth's upper mantle, and properties of olivine-rich melts are relevant to a variety of petrologic problems. Despite their prevalence and novelty, such glasses has not been studied thoroughly due to difficulties associated with their synthesis. Recently, Weber et al successfully prepared bulk olivine glass with the forsterite-composition Mg $_{2}$ SiO $_{4}$ using a containerless technique and initiated a neutron-diffraction investigation of the short-range structure of the glass. In this study, we present a result of the pulsed neutron diffraction experiment on the forsterite-composition glass. The neutron diffraction analysis suggests that highly distorted MgO $_{n}$ polyhedra are the major networking structural units in the forsterite-composition glass.

Journal Articles

Intermediate range order of vitreous silica studied by high energy X-ray diffraction, neutron diffraction and reverse Monte Carlo modelling

Kohara, Shinji*; Suzuya, Kentaro

Physics and Chemistry of Glasses, Vol.43C 2002, p.51 - 54, 2002/00

With the arrival of the latest generation of synchrotron sources and the introduction of advanced insertion devices, the high-energy (E 30keV) X-ray diffraction technique has become feasible, leading to new approaches in the quantitative study of the structure of disordered materials. Recently, the high-energy X-ray diffraction data have been combined with neutron diffraction data from a pulsed source to provide more detailed and reliable structural information than that hitherto available. We have developed a two-axis diffractometer for glass, liquid and amorphous materials at the SPring-8 high-energy X-ray diffraction beamline BL04B2. Furthermore, we have succeeded to analyze the intermediate-range order of a typical network forming glass, silica (SiO $_{2}$ ), by reverse Monte Carlo (RMC) modelling technique with special focused on the ring structures using both high-energy X-ray and neutron diffraction data.

Journal Articles

High-energy X-ray diffraction of disordered materials in high-energy X-ray diffraction beamline BL04B2 at SPring-8

Kohara, Shinji*; Suzuya, Kentaro

Hoshako, 14(5), p.365 - 375, 2001/11

http://ci.nii.ac.jp/naid/10007157514

no abstracts in English

Journal Articles

Structural studies of K $_{2}$ O-B $_{2}$ O $_{3}$ melts and glasses

Umesaki, Norimasa*; Kita, Y.*; Iida, T.*; Handa, K.*; Kohara, Shinji*; Suzuya, Kentaro; Fukunaga, Toshiharu*; Misawa, Masakatsu*

Physics and Chemistry of Glasses, 41(5), p.304 - 308, 2000/10

no abstracts in English

Oral presentation

In-situ stroboscopic neutron diffraction measurements during fatigue tests

Ito, Takayoshi*; Harjo, S.; Inamura, Yasuhiro; Kawasaki, Takuro; Nakatani, Takeshi; Akita, Koichi; Gong, W.; Aizawa, Kazuya

no journal, ,

We developed an event-recording system for recording information of neutron generation and detection and sample environmental conditions like load, strain, etc. as events with synchronized timing tag across whole system, and developed a software to handle the event data at the Engineering Materials Diffractometer TAKUMI at the Materials and Life Science Experimental Facility in J-PARC. It gave us several advantages by allowing us flexible data reduction depending on users' purposes, especially for time resolved experiments. We demonstrated in situ neutron diffraction measurements using these new recording system and software during fatigue test to show the advantages.

Oral presentation

Development of two-dimensional scintillation neutron detectors at J-PARC

Nakamura, Tatsuya; To, Kentaro; Sakasai, Kaoru

no journal, ,

We have developed scintillator-based neutron detectors by using wavelength-shifting (WLS) fiber technology for the MLF. The two-dimensional scintillator detectors we involved in the development were for single crystal neutron diffractometers iBIX and SENJU, where the pixel sizes of the detectors were optimized depending on the requirements, from 0.50.5 to 44 mm $^{2}$ . Based on this fiber technology we have enlarged a neutron-sensitive with a required pixel size for engineering materials diffractometer, TAKUMI. The WLS fiber technology has given us flexibility to design the pixel size to 55 mm $^{2}$ with a neutron-sensitive area of 320320 mm $^{2}$ . With the extension of this technique we plan to develop a larger area detector for SENJU, which has a neutron-sensitive area of 512512 mm $^{2}$ . In this paper details and recent progress of the detector development will be presented.

Oral presentation

Scientific trends in engineering materials diffractometer TAKUMI of J-PARC

Harjo, S.; Kawasaki, Takuro; Gong, W.*; Yamashita, Takayuki; Morooka, Satoshi; Harada, Tsuyoshi*; Aizawa, Kazuya

no journal, ,

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The Disordered 3-dimensional structure visualized by a combination of high-energy synchrotron X-rays and computer simulations

Unusual structure in vitreous forsterite synthesized by an aero-acoustic levitation technique

High-energy X-ray diffraction studies of short- and intermediate-range structure in oxide glasses

Neutron diffraction measurements of the structure of an orthosilicate glass: Mg $_{2}$ SiO $_{4}$

Intermediate range order of vitreous silica studied by high energy X-ray diffraction, neutron diffraction and reverse Monte Carlo modelling

High-energy X-ray diffraction of disordered materials in high-energy X-ray diffraction beamline BL04B2 at SPring-8

Structural studies of K $_{2}$ O-B $_{2}$ O $_{3}$ melts and glasses

In-situ stroboscopic neutron diffraction measurements during fatigue tests

Development of two-dimensional scintillation neutron detectors at J-PARC

Scientific trends in engineering materials diffractometer TAKUMI of J-PARC