Neutron-Diffraction and Thermometric Studies on Stress-Induced Redistribution of Hydrogen-Isotopes in Metallic Crystals
| Project/Area Number |
01550503
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Physical properties of metals
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| Research Institution | Tohoku University |
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Principal Investigator |
KAJITANI Tsuyoshi. Inst. Mat. Res. Tohoku Univ., Associate Prof., 金属材料研究所, 助教授 (80134039)
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| Co-Investigator(Kenkyū-buntansha) |
HIRAGA Kenji Inst. Mat. Res. Tohoku Univ., Prof., 教授 (30005912)
平林 真 いわき明星大学, 理工学部物性学科, 教授 (00005836)
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| Project Period (FY) |
1989 – 1990
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| Project Status |
Completed (Fiscal Year 1990)
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| Budget Amount *help |
¥2,300,000 (Direct Cost: ¥2,300,000)
Fiscal Year 1990: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1989: ¥1,700,000 (Direct Cost: ¥1,700,000)
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| Keywords | Neutron Diffraction / Specific Heat / Niobium / Tantalum / Stress / Strain / Microdomain / Diffuse Scattering / 中性子回析 / アルファ相 / Neutrou Diffraction / Metal Hydride / Metal Deuteride / Site Occupancy / Therwal Analysis / AC Thernal Analysis |
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| Research Abstract |
This two-years research project started to elucidate stress-induced redistribution of hydrogen-isotopes i. e. hydrogen and deuterium, stored in Va-group metals. In the first year, the research effort was focused on the static distribution of deuterium atoms in alopha -NbD_<0.2> which was at a stress-free state or under tensile or compressive monoaxial stresses applied parallel to [001] or [111] direction while the stress level was well controlled within the elastic limits. At the stress-free state, deuterium atoms site in the tetrahedral interstices in a statistical manner but site selective tetrahedral interstices in ways characteristic for the stress-types i. e. a compressive or a tensile stress, or stress-directions. The changes are similar to those occurred in alpha -VD_<0.3>. The research results were published in the reference [1]. A calorimetric measurement was carried out successfully on the alpha -NbH_<0.06>-_<0.10> to obtain the entropy/enthalpy change due to the redistributi
… More
on of hydrogen atoms associated with repeated, 1.5Hz, elastic stress.
In the second year, we were concentrated on the neutron diffraction and AC-calorimetric studies of alpha -TaH(D)_x with x<0.8, since it became imoportant to know the "normal" distribution of hydrogen isotopes at the stress-free state precisely. Careful neutron diffraction measurement onthe diffuse scatterings appeared in the alpha -TaD_<0.55> between the fundamental Bragg-reflections as well as in the vicinities of them was carried out. The AC-calorimetry in TaH_<0.1>-_<0.8> in the temperature range from 4K to 400K was done using a digital lock-in amplifier purchased with the grant-money. A tailing phenomenon was observed in the alpha -phase region just above the beta _1-> alpha or beta _2-> alpha phase transition temperature. Both the diffraction measurement and the calorimetry indicate that the hydrogen isotopes are in a short-range-ordered state at temperatures within 100K above the beta _1-> alpha or beta _2-> alpha phase transition temperature. A micro-domain model is proposed based on the measured short-range-order-parameter variation curves. These results are reported in the reference [2]. Less
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Report
(3 results)
Research Products
(6 results)
