Refine your search:     
Report No.
 - 
Search Results: Records 1-20 displayed on this page of 54

Presentation/Publication Type

Initialising ...

Refine

Journal/Book Title

Initialising ...

Meeting title

Initialising ...

First Author

Initialising ...

Keyword

Initialising ...

Language

Initialising ...

Publication Year

Initialising ...

Held year of conference

Initialising ...

Save select records

Journal Articles

Effect of strong gravitational field on oriented crystalline perovskite-type manganese oxide La$$_{1-x}$$Sr$$_x$$MnO$$_3$$

Tokuda, Makoto*; Mashimo, Tsutomu*; Khandaker, J. I.*; Ogata, Yudai; Mine, Yoji*; Hayami, Shinya*; Yoshiasa, Akira*

Journal of Materials Science, 51(17), p.7899 - 7906, 2016/09

 Times Cited Count:2 Percentile:10.2(Materials Science, Multidisciplinary)

Journal Articles

Influence of sedimentation of atoms on structural and thermoelectric properties of Bi-Sb alloys

Januszko, K.*; Stabrawa, A.*; Ogata, Yudai; Tokuda, Makoto*; Khandaker, J. I.*; Wojciechowski, K.*; Mashimo, Tsutomu*

Journal of Electronic Materials, 45(3), p.1947 - 1955, 2016/03

 Times Cited Count:2 Percentile:18.51(Engineering, Electrical & Electronic)

Journal Articles

Diffusion phenomenon at the interface of Cu-brass under a strong gravitational field

Ogata, Yudai*; Iguchi, Yusuke*; Tokuda, Makoto*; Januszko, K.*; Khandaker, J. I.*; Ono, Masao; Mashimo, Tsutomu*

Journal of Applied Physics, 117(12), p.125902_1 - 125902_6, 2015/03

 Times Cited Count:6 Percentile:32.7(Physics, Applied)

Journal Articles

Ultracentrifuge experiment on AgI super-ionic conductor

Ono, Masao; Okayasu, Satoru; Iguchi, Yusuke*; Esaka, Fumitaka; Bagum, R.*; Haruki, Rie; Mashimo, Tsutomu*

Transactions of the Japan Society for Aeronautical and Space Sciences, Aerospace Technology Japan (Internet), 12(ists29), p.Tq_1 - Tq_3, 2014/04

We had realized the composition gradient of elements or isotopes in some binary alloys or single element by solid-state centrifugation. While, it might difficult to realize graded structure of elements in binary ionic crystal by centrifugation as it strongly keeps their stoichiometry. However, isotope fractionation in binary ionic crystal by centrifugation might be expected as the self-diffusion of ions occurs. We have planed the ultracentrifuge experiments on $$alpha$$-AgI superionic conductor to investigate the isotope effect in binary ionic crystal under a strong centrifugal acceleration field. $$alpha$$-AgI superionic conductor is suitable for the confirmation experiment as it is an intrinsic ionic crystal and Ag ions have high diffusivity. For the first stage, we have experimentally searched the experimental conditions of magnitude of centrifugal acceleration and temperature that ensure the experiment without decomposition. It is confirmed that the combination of experimental conditions of up to 6.1$$times$$10$$^{5}$$ g, 350$$^{circ}$$C, 24h ensure the experiment without decomposition at least.

Journal Articles

Separation in $$varepsilon$$-phase of BiPb alloy under mega-gravity

Okayasu, Satoru; Ono, Masao; Nishio, Taichiro*; Iguchi, Yusuke*; Mashimo, Tsutomu*

Defect and Diffusion Forum, 323-325, p.545 - 548, 2012/04

 Times Cited Count:0 Percentile:0.01

Atomic sedimentation in solid occurs under mega-gravity treatment. As the result, partially melt-growth in $$varepsilon$$-phase of BiPb-alloy occurs. Small difference of densities between fully hcp structure of Bi$$_{3}$$Pb$$_{7}$$ and that of partially defected Bi$$_{3}$$Pb$$_{(7-delta)}$$ are enhanced under mega-gravity, and cause the separation of the $$varepsilon$$-phase. Superconducting properties differs between the separated two phases.

Journal Articles

Isotope distribution in pure indium after liquid-state centrifugation

Ono, Masao; Okayasu, Satoru; Esaka, Fumitaka; Haruki, Rie; Mashimo, Tsutomu*

Journal of the Japan Society of Microgravity Application, 28(2), p.S89 - S91, 2011/04

An ultracentrifuge experiment was performed on a pure liquid-indium at acceleration field of 8.2$$times$$10$$^{5}$$ g at 300$$^{circ}$$C for 100 hours. The isotope ratio measurements were performed on the centrifuged specimen with Secondary Ion Mass Spectrometer (CAMECA IMS-6f). $$^{113}$$In/$$^{115}$$In isotope ratio on the specimen changed with negative gradient in the direction of centrifugal force approximately 1.3%. The measurement result indicated that the heavy $$^{115}$$In isotopes moved in the direction of the centrifugal force and the light $$^{113}$$In isotopes moved in the counter direction in the specimen. At the session, we will present both the result and an approach to find a precondition to develop an isotope separation process using the phenomenon.

Journal Articles

Deformation twinning of Bi-Sb solid alloy formed under a strong gravitational field

Iguchi, Yusuke*; Mashimo, Tsutomu*; Ono, Masao; Okayasu, Satoru

Philosophical Magazine Letters, 90(7), p.513 - 518, 2010/07

 Times Cited Count:4 Percentile:32.25(Materials Science, Multidisciplinary)

We performed an ultracentrifuge experiment on Bi-Sb alloy. Deformation twins with misorientations of about 90 $$^{circ}$$ were observed in the low-gravitational region where grain refinement had not occurred. The twins were thicker than the conventional deformation twins and their thickness was proportional to the gravitational field. We found that the minimum gravitational field required for grain refinement was 1.7$$times$$10 $$^{5}$$ G at 240 $$^{circ}$$C for periods $$<$$ 10 h.

Journal Articles

Development of special rotor for centrifugal separation of isotopes in solid pure metals

Ono, Masao; Sueyoshi, Masanori*; Okayasu, Satoru; Hao, T.; Esaka, Fumitaka; Osawa, Takahito; Iguchi, Yusuke*; Mashimo, Tsutomu

Review of Scientific Instruments, 80(8), p.083908_1 - 083908_6, 2009/08

 Times Cited Count:3 Percentile:18.97(Instruments & Instrumentation)

A prototype rotor with 2 grooves for the multi-stage centrifugal isotope separation in solid state was developed to test a new idea. This idea is based on the sedimentation of constitutional atoms in solid. In the performance test using indium specimen, it is verified that the developed rotor can receive all injected molten-indium droplets from an automatic raw-material feeding system even at the high rotational speed of 97,000 r.p.m. without the loss of rotational stability, and the received indium specimens can be transferred in/between 2 grooves through the plastic flow under the influence of strong centrifugal force even in the solid state. The isotope ratio of centrifuged indium specimens was analyzed employing the Secondary Ion Mass Spectrometry (SIMS), and it is confirmed that intended isotope separation by the centrifugation is realized in the solid state.

Journal Articles

Isotope fractionation due to sedimentation of atoms in centrifuged indium-lead alloy

Ono, Masao; Iguchi, Yusuke*; Okayasu, Satoru; Esaka, Fumitaka; Kobayashi, Katsura*; Hao, T.; Bagum, R.*; Osawa, Takahito; Fujii, Kimio; Nakamura, Eizo*; et al.

Defect and Diffusion Forum, 289-292, p.63 - 68, 2009/04

The atomic-scale graded structure of In-Pb alloy was formed by an ultracentrifuge experiment under conditions that a gravitational field of 0.81$$times$$10$$^{6}$$ G for 100 hours at 150 $$^{circ}$$C in solid state in our previous study. The isotope ratio measurements were performed on the centrifuged sample with secondary ion mass spectrometer (SIMS). $$^{206}$$Pb/$$^{208}$$Pb and $$^{207}$$Pb/$$^{208}$$Pb isotope ratio changed with negative gradient in the direction of centrifugal force approximately 1.5% and 0.8%, respectively. And three-isotope diagram of $$^{206}$$Pb/$$^{208}$$Pb versus $$^{207}$$Pb/$$^{208}$$Pb proved that the isotope fluctuation depends on isotopic mass difference. These results showed that the strong gravitational field not only affected on the inter-diffusion but also on self-diffusion in this alloy as causing isotope fractionation effect, and the isotope fractionation was dependent on mass-difference.

Journal Articles

Sedimentation of impurity atoms in InSb semiconductor under a strong gravitational field

Iguchi, Yusuke*; Ono, Masao; Okayasu, Satoru; Mashimo, Tsutomu

Defect and Diffusion Forum, 289-292, p.319 - 322, 2009/04

An atomic-scale graded structure has been formed by sedimentation of substitutional atoms under an ultra-strong gravitational field of 1 million G level in alloys and compounds. In this study, we investigate the sedimentation of impurity atoms in semiconductor materials under a strong gravitational field. High-temperature ultracentrifuge experiments (0.59$$times$$10$$^{6}$$ G, 400$$^{circ}$$C, 60 hours) have been performed on an InSb single crystal wafer which surface was coated with Ge by means of Physical Vapor Deposition (PVD). It was observed that the penetration depth of diffused Ge atoms under the gravitational field was several times larger than under terrestrial field at the same temperatures.

Journal Articles

Formation of amorphous graded structure in Bi$$_{3}$$Pb$$_{7}$$ intermetallic compounds under strong gravitational field

Mashimo, Tsutomu; Iguchi, Yusuke*; Bagum, R.*; Sano, Tomokazu*; Takeda, Shingo*; Kimura, Shigeru*; Sakata, Osami*; Ono, Masao; Okayasu, Satoru; Tsurui, Takao*; et al.

Defect and Diffusion Forum, 289-292, p.357 - 360, 2009/04

A visible four-layers structure with anomalous nano-sturucture was formed from a homogeneous e-phase Bi$$_{3}$$Pb$$_{7}$$ intermetallic compound under a strong gravitational field (1.02$$times$$10$$^{6}$$ G, 130$$^{circ}$$C, 100 hours). In the 4th layer (lowest-gravity region), pure Bi particles precipitate. In the 2nd 3rd layers, composition graded structures, where Pb content increased along the gravity direction, were formed. It was found that the very broad XRD peak appeared in the 2nd layer, which indicated that an amorphous structure was contained.

Journal Articles

Strong-gravity effect on twinned Y$$_{1}$$Ba$$_{2}$$Cu$$_{3}$$O$$_{7-x}$$ single crystal

Bagum, R.*; Okayasu, Satoru; Iguchi, Yusuke*; Ono, Masao; Mashimo, Tsutomu

Defect and Diffusion Forum, 289-292, p.517 - 521, 2009/04

Ultracentrifuge experiments were performed on the twinned Y$$_{1}$$Ba$$_{2}$$Cu$$_{3}$$O$$_{7-x}$$ (Y123) single crystal at much lower temperatures than the melting point. Two layers structure with slightly different compositions was observed in the sample ultracentrifuged at 250 $$^{circ}$$C (380,000 G), which might be due to the sedimentation of atoms. In the strong gravity layer, it was found that the Y123 phase disappeared, and unknown XRD peaks appeared. Decomposition occurred in the sample ultracentrifuged at 400 $$^{circ}$$C.

Journal Articles

Mass-dependent isotopic fractionation of a solid tin under a strong gravitational field

Osawa, Takahito; Ono, Masao; Esaka, Fumitaka; Okayasu, Satoru; Iguchi, Yusuke*; Hao, T.; Magara, Masaaki; Mashimo, Tsutomu

EPL; A Letters Journal Exploring the Frontiers of Physics, 85(6), p.64001_1 - 64001_5, 2009/03

 Times Cited Count:5 Percentile:39(Physics, Multidisciplinary)

Pure tin metals were centrifuged at 1$$times$$$$10^6$$ $$g$$ and at 220 $$^{circ}$$C for 100 hours, 0.40$$times$$$$10^6$$ $$g$$ at 220-230 $$^{circ}$$C for 24 hours, and 0.25$$times$$$$10^6$$ $$g$$ at 220 $$^{circ}$$C for 24 hours. Their isotopic compositions were measured by a secondary ion mass spectrometer (SIMS). $$^{116}$$Sn/$$^{120}$$Sn and $$^{124}$$Sn/$$^{120}$$Sn ratios of the 1.02$$times$$$$10^6$$ $$g$$ sample were considerably different than the initial compositions, and the magnitude of isotopic fractionation reached 2.6%. A three-isotope diagram of $$^{116}$$Sn/$$^{120}$$Sn versus $$^{124}$$Sn/$$^{120}$$Sn shows conclusively that isotopic fractionation caused by a gravitational field depended only on isotopic mass.

Journal Articles

Isotope fluctuation in indium-lead alloy induced by solid centrifugation

Ono, Masao; Iguchi, Yusuke*; Okayasu, Satoru; Esaka, Fumitaka; Kobayashi, Katsura*; Hao, T.; Bagum, R.*; Osawa, Takahito; Fujii, Kimio; Nakamura, Eizo*; et al.

Journal of Nuclear Science and Technology, 45(Suppl.6), p.108 - 110, 2008/09

 Times Cited Count:1 Percentile:10.92(Nuclear Science & Technology)

The atomic-scale graded structure of In-Pb alloy was formed by an ultracentrifuge experiment under conditions that a gravitational field of 810,000 G for 100 hours at 150$$^{circ}$$C (solid state) in our previous study. The isotope fluctuation on this sample was measured using secondary ion mass spectrometer (SIMS). The ratio both $$^{208}$$Pb/$$^{206}$$Pb and $$^{115}$$In/$$^{113}$$In changed with positive gradient in the direction of centrifugal force approximately 1.2%. These isotope fluctuations were larger than that of starting state of natural state (In$$<$$0.2%, Pb$$<$$0.1%). These show that the sedimentation of isotopes occurred by solid centrifugation in this alloy, although achieved concentration gradients were small.

Journal Articles

Isotope separation by condensed matter centrifugation; Sedimentation of isotope atoms in Se

Mashimo, Tsutomu; Ono, Masao; Huang, X.*; Iguchi, Yusuke*; Okayasu, Satoru; Kobayashi, Katsura*; Nakamura, Eizo*

Journal of Nuclear Science and Technology, 45(Suppl.6), p.105 - 107, 2008/09

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

It was observed that the concentration ratio $$^{82}$$Se/$$^{76}$$Se increased by % level in the specimen ultracentrifuged at 0.7$$sim$$0.9 million G and at 300$$^{circ}$$C(liquid state) or 190$$^{circ}$$C (solid state), respectively. The present result is evidence of sedimentation of substitutional atoms in condensed matter via self-diffusion, and suggests its possible application to isotope separation by condensed matter centrifugation.

Journal Articles

Ultracentrifuge experiment on an Mg-Cd order-disorder alloy

Ono, Masao; Iguchi, Yusuke*; Bagum, R.*; Fujii, Kimio; Okayasu, Satoru; Esaka, Fumitaka; Mashimo, Tsutomu*

AIP Conference Proceedings 973, p.476 - 481, 2008/03

We had realized atomic-scale graded structures in several miscible alloys by ultracentrifuge experiment. In this study, we performed an ultracentrifuge experiment on a MgCd order-disorder alloy at disordered state of solid solution. The experimental conditions were as follows: maximum acceleration: 610,000 g, temperature: 400$$^{circ}$$C, composition: Mg:Cd=50:50at%, time duration: 60 h). We investigated the crystal state of the centrifuged sample that had ordered from the disorder state of atomic-scale graded structure. It was found that the graded structure was formed in the centrifuged sample, in which Cd content continuously increased in the direction of gravitational field. It was also found that the different peaks from the starting state appeared in X-ray diffraction patterns of the centrifuged sample. We will present details at the session.

Journal Articles

Formation of multi-layer structures in Bi$$_{3}$$Pb$$_{7}$$ intermetallic compounds under an ultra-high gravitational field

Mashimo, Tsutomu; Iguchi, Yusuke*; Bagum, R.*; Sano, Tomokazu*; Sakata, Osami*; Ono, Masao; Okayasu, Satoru

AIP Conference Proceedings 973, p.502 - 505, 2008/03

Ultra-high gravitational field (Mega-gravity field) can realize the sedimentation of atoms (diffusion) even in solids, and is expected to form a composition-graded structure and/or nonequilibrium phase in multi-component condensed matter. We had realized the sedimentation of substitutional solute atoms in miscible systems (Bi-Sb, In-Pb, etc.). In this study, the mega-gravity experiment at high temperature was performed on a thin-plate sample (0.7 mm in thickness) of intermetallic compound Bi$$_{3}$$Pb$$_{7}$$. A visible four-layers structure appeared, which indicated different microscopic structures. In the lowest-gravity region layer, Bi phase appeared. In the mid layers, the composition-graded structure was formed, while the powder X-ray diffraction patterns show difference. Such multi-layers structure was expected to show unique physical properties such as superconductivity. Keywords: Sedimentation of atoms, Ultra-high gravity field, Bi$$_{3}$$Pb$$_{7}$$, Graded structure.

Journal Articles

Gravity-induced diffusion of isotope atoms in monoatomic solid Se

Mashimo, Tsutomu; Ono, Masao; Huang, X. S.*; Iguchi, Yusuke*; Okayasu, Satoru; Kobayashi, Katsura*; Nakamura, Eizo*

Europhysics Letters, 81(5), p.56002_1 - 56002_4, 2008/03

 Times Cited Count:12 Percentile:61.26(Physics, Multidisciplinary)

A strong gravitational field resulted in the gravity-induced diffusion (sedimentation) of isotope atoms in monoatomic solid Se. The layer crystalline morphology consisting of three zones of the fine-grained crystals, the long crystals and feather-shaped crystals grown parallel to gravity direction appeared in the specimen ultracentrifuged at 0.8-1 million G and at 190 $$^{circ}$$C. Change in concentration ratio $$^{82}$$Se/$$^{76}$$Se of $$>$$ 0.8% was observed in the grown crystalline region. These results show an evidence for sedimentation of substitutional atoms in solid via self-diffusion, and suggest possibility of application to control of impurity and crystalline state as well as to isotope separation.

Journal Articles

Chemistry in mega-gravity; Preparation of molecular-scaled graded materials from radical copolymerization

Ihara, Hirotaka; Abe, Yasuyuki*; Miyamoto, Akihiro*; Nishihara, Masamichi*; Takafuji, Makoto*; Ono, Masao; Okayasu, Satoru; Mashimo, Tsutomu

Chemistry Letters, 37(2), p.200 - 201, 2008/02

 Times Cited Count:1 Percentile:7.97(Chemistry, Multidisciplinary)

The molecular-graded structures have been realized through direct copolymerization of halogenated styrene and 2-ethylhexyl methacrylate under ultra-strong gravitational field. The graded structures were clearly confirmed by EPMA and NMR spectroscopy.

Journal Articles

Sedimentation of isotope atoms in monatomic liquid Se

Mashimo, Tsutomu; Ono, Masao; Huang, X. S.*; Iguchi, Yusuke*; Okayasu, Satoru; Kobayashi, Katsura*; Nakamura, Eizo*

Applied Physics Letters, 91(23), p.231917_1 - 231917_3, 2007/12

 Times Cited Count:20 Percentile:62.16(Physics, Applied)

A strong gravitational field resulted in the sedimentation of isotope atoms in monatomic liquid. The concentration ratio $$^{82}$$Se/$$^{76}$$Se increased by greater than 3.5% in specimen ultracentrifuged at 0.7$$sim$$0.9 million G and at 300$$^{circ}$$C. The recovered sample had a feather-shaped crystalline morphology. The concentration gradient was nearly twice that of the steady state analytical result (ideal gas system), indicating a non-ideal system diffusion. The present result is evidence of sedimentation of substitutional atoms in condensed matter via self-diffusion, and suggestes its possible application to isotope separation, crystalline control and matter dynamics in massive star.

54 (Records 1-20 displayed on this page)