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Journal Articles

Effect of uranium deficiency on normal and superconducting properties in unconventional superconductor UTe$$_2$$

Haga, Yoshinori; Opletal, P.; Tokiwa, Yoshifumi; Yamamoto, Etsuji; Tokunaga, Yo; Kambe, Shinsaku; Sakai, Hironori

Journal of Physics; Condensed Matter, 34(17), p.175601_1 - 175601_7, 2022/04

Journal Articles

Phase-field model for crystallization in alkali disilicate glasses; Li$$_2$$O-2SiO$$_2$$, Na$$_2$$O-2SiO$$_2$$ and K$$_2$$O-2SiO$$_2$$

Kawaguchi, Munemichi; Uno, Masayoshi*

Journal of the Ceramic Society of Japan, 128(10), p.832 - 838, 2020/10

 Times Cited Count:0 Percentile:0.01(Materials Science, Ceramics)

This study developed phase-field method (PFM) technique in oxide melt system by using a new mobility coefficient ($$L$$). The crystal growth rates ($$v_0$$) obtained by the PFM calculation with the constant $$L$$ were comparable to the thermodynamic driving force in normal growth model. The temperature dependence of the $$L$$ was determined from the experimental crystal growth rates and the $$v_0$$. Using the determined $$L$$, the crystal growth rates ($$v$$) in alkali disilicate glasses, Li$$_2$$O-2SiO$$_2$$, Na$$_2$$O-2SiO$$_2$$ and K$$_2$$O-2SiO$$_2$$ were simulated. The temperature dependence of the $$v$$ was qualitatively and quantitatively so similar that the PFM calculation results demonstrated the validity of the $$L$$. Especially, the $$v$$ obtained by the PFM calculation appeared the rapid increase just below the thermodynamic melting point ($$T_{rm m}$$) and the steep peak at around $$T_{rm m}$$-100 K. Additionally, as the temperature decreased, the $$v$$ apparently approached zero ms$$^-1$$, which is limited by the $$L$$ representing the interface jump process. Furthermore, we implemented the PFM calculation for the variation of the parameter $$B$$ in the $$L$$. As the $$B$$ increased from zero to two, the peak of the $$v$$ became steeper and the peak temperature of the $$v$$ shifted to the high temperature side. The parameters $$A$$ and $$B$$ in the $$L$$ increased exponentially and decreased linearly as the atomic number of the alkali metal increased due to the ionic potential, respectively. This calculation revealed that the $$A$$ and $$B$$ in the $$L$$ were close and reasonable for each other.

Journal Articles

Deuteron ordering in ice containing impurities; A Neutron diffraction study

Fukazawa, Hiroshi; Hoshikawa, Akinori; Yamauchi, Hiroki; Yamaguchi, Yasuo*; Igawa, Naoki; Ishii, Yoshinobu

Physica B; Condensed Matter, 385-386(1), p.113 - 115, 2006/11

 Times Cited Count:3 Percentile:18.82(Physics, Condensed Matter)

We measured neutron diffraction of powdered samples of ice containing impurities (e.g., potassium deuteroxide, sodium deuteroxide) to analyze the formation of ice XI, a deuterium-ordered phase of ice, from ice Ih, a disordered phase. We found that the diffraction profiles changed with time for several days at 62-70 K, which are below the transition temperature $$T$$$$_{rm c}$$ = 76 K. From the Rietveld analysis of the diffraction profiles, we determined the change of the structural parameters with the phase transition. The structural analysis provides direct evidence for the existence of deuteron-ordered arrangements in ice containing impurities below $$T$$$$_{rm c}$$. On the basis of the Rietveld analysis, we obtained the mass fraction ($$f$$) of ice XI as functions of time and temperature. We report a structural observation for the nucleation and growth of ice XI under various conditions (such as temperature variations and impurity effects), which leads to understand whether or not f reaches unity at an infinite annealing time.

Journal Articles

Single crystal growth and crystal structure of ThRhIn$$_5$$ and LuCoGa$$_5$$

Matsuda, Tatsuma; Haga, Yoshinori; Sakai, Hironori; Ikeda, Shugo; Onuki, Yoshichika

Journal of the Physical Society of Japan, 75(Suppl.), p.85 - 87, 2006/08

Recently quasi-two-dimensional electron state in rare earth and actinide compounds with HoCoGa$$_5$$-type tetragonal crystal structure was attracted a lot attention in relation to heavy fermion superconductivity observed in CeCoIn$$_5$$, CeIrIn$$_5$$ and PuCoGa$$_5$$. In order to elucidate the role of $$f$$ electron in these compounds, it is necessary to compare their electronic state with that of lanthanum and thorium compounds which do not possess the $$f$$-electrons. The number of valence electrons in the thorium compound is the same as that of the corresponding 4$$f^1$$-itinerant cerium compound. We have recently tried to make thorium 115 compounds by indium flux method and have succeeded in discovering the new material of ThRhIn$$_5$$. Crystal structure and quality were confirmed by X-ray diffraction, fluorescent X-ray analysis and EPMA. The lattice parameters were determined to be 4.681(6) $AA and 7.54(1) AA for $a$$ and $$c$$, respectively. The positional parameter $$z$$ of In(4$$i$$) site was also determined to be $$z=0.3069(1)$$.

Journal Articles

Single crystal growth and observation of the de Haas-van Alphen effect in ThIn$$_3$$

Matsuda, Tatsuma; Haga, Yoshinori; Shishido, Hiroaki*; Ikeda, Shugo; Harima, Hisatomo*; Settai, Rikio*; Onuki, Yoshichika

Physica B; Condensed Matter, 378-380, p.1021 - 1022, 2006/05

 Times Cited Count:0 Percentile:0(Physics, Condensed Matter)

We have succeeded in growing a high-quality single crystal of ThIn$$_3$$ with the cubic structure by the In-flux method and measured the de Haas-van Alphen (dHvA) effect. Several dHvA branches were observed, ranging from 9.0 $$times$$ 10$$^6$$ to 9.37 $$times$$ 10$$^8$$ Oe. The experimental results are compared to the dHvA results of CeIn$$_3$$ under pressure of 2.7 GPa, together with the results of energy band calculations.

Journal Articles

Spectroscopic properties of Yb doped YLF grown by a vertical Bridgman method

Sugiyama, Akira; Katsurayama, Masamichi*; Anzai, Yutaka*; Tsuboi, Taiju*

Journal of Alloys and Compounds, 408-412, p.780 - 783, 2006/02

 Times Cited Count:21 Percentile:75.01(Chemistry, Physical)

Laser crystals of LiYF$$_{4}$$ (YLF) doped with 5 - 64 at.% of trivalent ytterbium ions (Yb$$^{3+}$$) were grown by a vertical Bridgman method. As crystal growth materials of YbF$$_{3}$$ and YF$$_{3}$$ including YOF impurities caused opaque crystal, the YOF reduction procedure using PbF$$_{2}$$ was essential before starting the crystal growth. We derived seven energy levels from the $$^{2}$$F$$_{7/2}$$ and $$^{2}$$F$$_{5/2}$$ manifolds of Yb$$^{3+}$$: YLF by the crystal-field analysis from which we explain the observed polarized absorption and emission spectra. The intrinsic broad and complicated spectra of Yb$$^{3+}$$: YLF are attributed to the strong coupling of the 4f electrons with lattice vibration of the crystal.

Journal Articles

Electrical and magnetic properties of a single crystal UCu$$_2$$Si$$_2$$

Matsuda, Tatsuma; Haga, Yoshinori; Ikeda, Shugo; Galatanu, A.; Yamamoto, Etsuji; Shishido, Hiroaki*; Yamada, Mineko*; Yamaura, Junichi*; Hedo, Masato*; Uwatoko, Yoshiya*; et al.

Journal of the Physical Society of Japan, 74(5), p.1552 - 1556, 2005/05

 Times Cited Count:21 Percentile:70.75(Physics, Multidisciplinary)

We have succeeded in growing a high-quality single crystal of UCu$$_2$$Si$$_2$$ with the tetragonal structure by the Sn-flux method and measured the electrical resistivity, magnetic susceptibility, magnetization and specific heat. UCu$$_2$$Si$$_2$$ is found to order antiferromagnetically below $$T_{rm N}$$ = 106 K, and follows a successive ferromagnetic ordering at $$T_{rm C}$$ = 100 K. The magnetic properties are highly anisotropic, reflecting the crystal structure. An easy-axis of magnetization is found to be the [001] direction ($$c$$-axis) both in the antiferromagnetic and ferromagnetic phases, while the [100] direction ($$a$$-axis) corresponds to the hard-axis in magnetization. The magnetization curve in the antiferromagnetic phase indicates a clear metamagnetic transition at a low field of about 1 kOe and changes smoothly into a ferromagnetic magnetization curve below $$T_{rm C}$$ = 100 K. The saturation moment is determined as 1.75$$mu_{rm B}$$/U at 2 K. The electronic specific heat coefficient is also determined as 20 mJ/K$$^2$$$$cdot$$mol.

Journal Articles

Small saturation moment due to the crystalline electric field effect for $$T_h$$ site symmetry in the ferromagnet UFe$$_4$$P$$_{12}$$

Matsuda, Tatsuma; Galatanu, A.; Haga, Yoshinori; Ikeda, Shugo; Yamamoto, Etsuji; Hedo, Masato*; Uwatoko, Yoshiya*; Takeuchi, Tetsuya*; Sugiyama, Kiyohiro*; Kindo, Koichi*; et al.

Journal of the Physical Society of Japan, 73(9), p.2533 - 2538, 2004/09

 Times Cited Count:8 Percentile:49.43(Physics, Multidisciplinary)

Electrical resistivity, specific heat, magnetic susceptibility and high-field magnetization measurements have been performed on the ferromagnet UFe$$_{4}$$P$$_{12}$$ with the cubic crystal structure. The ferromagnetic ordering at $$T_{rm C}$$,=,3.1 K, a small saturation moment of 1.3 $$mu_{rm B}$$/U, together with the temperature dependence of the magnetic susceptibility, are found to be well explained by considering the 5$$f^2$$ crystalline electric field schemes for $$T_{h}$$ site symmetry and the magnetic exchange interaction.

Journal Articles

Effects of ultrastrong gravitational field on the crystalline state of a Bi-Sb alloy

Huang, X.*; Mashimo, Tsutomu; Ono, Masao; Tomita, Takeshi; Sawai, Tomotsugu; Osakabe, Toyotaka; Mori, Nobuo*

Journal of Applied Physics, 96(3), p.1336 - 1340, 2004/08

 Times Cited Count:11 Percentile:44.13(Physics, Applied)

Mega-gravity field experiments were performed on the Bi$$_{70}$$Sb$$_{30}$$(atomic percent) alloy and pure Bi below their melting points, to investigate the change in crystalline state. For the alloy centrifuged at 191-205 $$^{circ}$$C, no change in composition was observed, and the grain sizes of the crystals decreased from several mm to tens of $$mu$$m, while no distinct change in grain size was observed for the centrifuged pure Bi. The alloy centrifuged at 220-240 $$^{circ}$$C consisted of two regions with different morphologies-fine-grained crystals with grain sizes around tens of $$mu$$m in the low gravity region, and large crystals with grain sizes several mm long and hundreds of $$mu$$m wide along the direction of gravity in the high gravity region, where sedimentation of atoms was confirmed. The large crystals with hexagonal structures were formed by preferential crystal growth roughly along the c axes, and a large strain that increased as the gravitational field increased existed inside these crystals. Formation of this anomalous crystal state might be correlated with the sedimentation of atoms.

Journal Articles

More rapid evaluation of biomacromolecular crystals for diffraction experiments

Arai, Shigeki; Chatake, Toshiyuki; Suzuki, Nobuhiro*; Mizuno, Hiroshi*; Niimura, Nobuo

Acta Crystallographica Section D, 60(6), p.1032 - 1039, 2004/06

 Times Cited Count:16 Percentile:75.95(Biochemical Research Methods)

The parameters used for evaluating biomacromolecular crystal quality (${it R}$$$_{merge}$$, ${it I}$/$$sigma$$(${it I}$), maximum resolution and mosaicity) strongly depend on the diffraction experimental conditions. In this paper we describe the distinctive features of the relative Wilson plot method, and we show that the overall B-factor obtained from this plot is given as a more appropriate to characterize protein crystals. The relative Wilson plot has been applied to the characterization of crystals of a B-DNA decamer d(CCATTAATGG), and crystals of the proteins DsrD (dissimilatory sulfite reductase D) and hen egg-white lysozyme (HEWL) which we have studied by neutron diffraction. We have found that the crystal qualities of the B-DNA decamer and DsrD significantly depend on the regions of the crystallization phase diagram from which samples were taken. However, in the case of HEWL, crystal quality appears to be independent on the region of the crystallization phase diagram.

Journal Articles

SR-excited process

Teraoka, Yuden

Nano Tekunoroji Daijiten, p.340 - 351, 2003/12

The current status of microprocesses using synchrotron radiation in Japan was reviewed. The SR-excited process is followed by SR-excited surface modification, SR-excited crystal growth and SR-excited etching. The SR-excited surface modification is followed by SR-gas-excited surface modification and SR-direct-excited surface modification. The SR-excited crystal growth is followed by SR-excited atomic layer epitaxy and SR-excited chemical vapor deposition. THe SR-excited etching is followed by SR-direct-excited etching, SR-gas-excited etching and SR ablation.

Journal Articles

Single crystal growth and magnetic properties of ferromagnetic URhGe$$_2$$

Matsuda, Tatsuma; Haga, Yoshinori; Tokiwa, Yoshifumi; Andrei, G.; Yamamoto, Etsuji; Okubo, Tomoyuki*; Onuki, Yoshichika

Acta Physica Polonica B, 34(2), p.1071 - 1074, 2003/02

We have successfully grown a single crystal of uranium intermetallic compound URhGe$$_2$$. The temperature dependence of electrical resistivity shows highly anisotropic behavior. Two anomalies, which correspond to the magnetic ordering temperatures, were observed in the resistivity, magnetic susceptibility and specific heat measurements at $$T_{rm M1}$$= 30 K and $$T_{rm M2}$$=25 K. The magnetic susceptibility also shows a large uniaxial anisotropy with a magnetic easy-axis along the [010] direction.

Journal Articles

High-quality epitaxial TiO$$_{2}$$ thin films grown on $$alpha$$-Al$$_{2}$$O$$_{3}$$ substrates by pulsed laser deposition

Shinohara, Ryuji*; Yamaki, Tetsuya; Yamamoto, Shunya; Ito, Hisayoshi; Asai, Keisuke*

Journal of Materials Science Letters, 21(12), p.967 - 969, 2002/06

 Times Cited Count:9 Percentile:38.24(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

A Three-step process for epitaxial growth of (111)-oriented C$$_{60}$$ films on alkali-halide substrates

Dai, Z.*; Naramoto, Hiroshi; Narumi, Kazumasa; Yamamoto, Shunya; Miyashita, Atsumi

Thin Solid Films, 360(1), p.28 - 33, 2000/02

 Times Cited Count:2 Percentile:16.19(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Self-mediated growth of single-crystal and entirely(111)-oriented C$$_{60}$$ films on alkali halide substrates

Dai, Z.*; Naramoto, Hiroshi; Narumi, Kazumasa; Yamamoto, Shunya; Miyashita, Atsumi

Applied Physics Letters, 74(12), p.1686 - 1688, 1999/03

 Times Cited Count:5 Percentile:29.14(Physics, Applied)

no abstracts in English

Journal Articles

Control of film orientation; A Parametric study of laser ablated FTO films on a-, c- and r-cut sapphire substrates by X-ray diffraction

Dai, Z.*; Miyashita, Atsumi; Yamamoto, Shunya; Narumi, Kazumasa; Naramoto, Hiroshi

Thin Solid Films, 349(1-2), p.51 - 55, 1999/00

 Times Cited Count:3 Percentile:23.36(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Crystal growth mechanism of YBa$$_{2}$$Cu$$_{3}$$O$$_{x}$$ from coexisting region of solid with melt

Asaoka, Hidehito; *; Noda, Kenji

Japanese Journal of Applied Physics, 33(7A), p.L923 - L926, 1994/07

 Times Cited Count:5 Percentile:35.73(Physics, Applied)

no abstracts in English

Journal Articles

Growth of large isometric YBa$$_{2}$$Cu$$_{3}$$O$$_{x}$$ single crystals from coexisting region of solid with melt in Y$$_{2}$$O$$_{3}$$ crucibles

Asaoka, Hidehito; *; *; *; *; *

Japanese Journal of Applied Physics, 32(3A), p.1091 - 1096, 1993/03

 Times Cited Count:54 Percentile:90.71(Physics, Applied)

no abstracts in English

Journal Articles

Observation of YBa$$_{2}$$Cu$$_{3}$$O$$_{x}$$ crystal growth from solid-liquid mixtures by using quenching experiments

Asaoka, Hidehito; Noda, Kenji; *

Nihon Kessho Seicho Gakkai-Shi, 20(2), 92 Pages, 1993/00

no abstracts in English

Journal Articles

Cell formation and interfacial instability in laser-annealed Si-In and Si-Sb alloys

J.Narayan*; ; C.W.White*

Journal of Applied Physics, 53(2), p.912 - 915, 1982/00

 Times Cited Count:16 Percentile:64.73(Physics, Applied)

no abstracts in English

22 (Records 1-20 displayed on this page)