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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

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

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

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:10.12(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

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.

Oral presentation

Ultracentrifuge experiment on a Mg-Cd order-disorder alloy

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

no journal, , 

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.

Oral presentation

Sedimentation of atoms in a Mg-Cd order-disorder alloy

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

no journal, , 

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.

Oral presentation

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.

no journal, , 

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, CAMECA IMS-6f). Both $$^{115}$$In/$$^{113}$$In and $$^{208}$$Pb/$$^{206}$$ isotope ratio changed with negative gradient in the direction of centrifugal force approximately 1.2% showing the tendency that the heavy $$^{115}$$In isotope ($$^{208}$$Pb isotope) abundance increased and light $$^{113}$$In isotope ($$^{206}$$Pb isotope) abundance decreased in the direction of centrifugal force. This showed that the isotope fractionation effect due to sedimentation of atoms occurred in this alloy by ultracentrifuge experiment.

Oral presentation

Ag isotope fractionation in a centrifuged $$alpha$$-AgI super-ionic conductor

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

no journal, , 

no abstracts in English

Oral presentation

Ag isotope fractionation in a centrifuged $$alpha$$-AgI super-ionic conductor

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

no journal, , 

no abstracts in English

Oral presentation

Ag isotope fractionation in a centrifuged $$alpha$$-AgI super-ionic conductor

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

no journal, , 

The ultracentrifuge experiment was performed on an $$alpha$$-AgI super-ionic conductor at acceleration field of 6.1$$times$$10$$^{5}$$ g at 220$$^{circ}$$C for 100 hours. From the analysis using Electron Probe Micro Analyzer (EPMA) and micro-area X-Ray Diffractometer, it was confirmed that the centrifuged specimen kept its stoichiometry. The isotope ratio measurements were performed on the centrifuged specimen with Secondary Ion Mass Spectrometer (SIMS). $$^{107}$$Ag/$$^{109}$$Ag isotope ratio on the specimen changed with negative gradient in the direction of centrifugal force approximately 1.5%. These observations indicated that the heavy $$^{109}$$Ag isotopes moved in the direction of the centrifugal force and the light $$^{107}$$Ag isotopes moved in the counter direction keeping charge balance in the specimen.

Oral presentation

Isotope effect in AgI super-ionic conductor by centrifugation

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

no journal, , 

The ultracentrifuge experiment was performed on an $$alpha$$-AgI super-ionic conductor at acceleration field of 6.1$$times$$10$$^{5}$$ g at 220$$^{circ}$$C for 100 hours. It was confirmed that the centrifuged specimen kept its stoichiometry by the analysis using Electron Probe Micro Analyzer and micro-area X-Ray Diffractometer. The isotope ratio measurements on the centrifuged specimen were performed using Secondary Ion Mass Spectrometer (CAMECAIMS-6f). The isotope ratio of $$^{107}$$Ag/$$^{109}$$Ag on the specimen changed with negative gradient in the direction of centrifugal force approximately 1.5%. These observation results indicated that the heavy $$^{109}$$Ag isotopes moved in the direction of the centrifugal force and the light $$^{107}$$Ag isotopes moved in the counter direction keeping their charge balance in the specimen.

Oral presentation

Isotope distribution in AgI super-ionic conductor after centrifugation

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

no journal, , 

The ultracentrifuge experiments were performed on $$alpha$$-AgI super-ionic conductor samples. It was confirmed that all centrifuged specimens kept their stoichiometry. The isotope ratio of $$^{107}$$Ag/$$^{109}$$Ag on specimens changed with negative gradient in the direction of centrifugal force. These results indicated that the heavy isotopes moved in the direction of the centrifugal force and the light isotopes moved in the counter direction keeping their charge balance in the specimen.

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