1995 Fiscal Year Final Research Report Summary
Study on the Development of High Efficient Materials for Generation of Very Low Temperatures
| Project/Area Number |
05555178
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| Research Category |
Grant-in-Aid for Developmental Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
Structural/Functional materials
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| Research Institution | TOHOKU UNIVERSITY |
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Principal Investigator |
FUKAMICHI Kazuaki Faculty of Engineering, Tohoku University Professor, 工学部, 教授 (00005969)
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| Co-Investigator(Kenkyū-buntansha) |
SAHASHI Masashi TOSHIBA Corp. Advanced Research Lab. Research and Development Center, Hard of Re, 材料デバイス研究所, 主任研究員
SUZUKI Kenji Institute for Materials Research, Tohoku University, Professor, 金属材料研究所, 教授 (10005861)
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| Project Period (FY) |
1993 – 1995
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| Keywords | Magnetic moment / Low-temperature specific heat / Magnetic entropy / Heat capacity / Amorphous alloys / Rare earth compound / Quasicrystal |
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| Research Abstract |
In the field of cryogenics, cold media such as helium and technics of generation for low temperatures are important. For gas refrigeration, high efficient reservoirs are necessary to generate very low temperatures. The reservoir receives the heat carried out by the Carnot cycle.
Pb has conventionally used as a reservoir. In this case, it is impossible to generate low temperatures below 10 K.This prevents using widely helium. In the present study, the development of the high efficient reservoir has been carried out in order to overcome the berrier mentioned above.
Until last year, various compounds and alloys with a heat capacity as large as possible have been investigated. It has become clear by low-temperature specific heat measurements that rare earth compound HoPb_2 with a large magnetic moment has a large heat capacity, compared with that of Er-Ni compounds which have high potentials for applications. However, this compound is not so good as the reservoir because of the ready oxidation at atmosphere. The low temperature specific heat measurements for amorphous alloys with a large random magnetic anisotropy and quasicrystals containing rare earth element have been carried out. However, the heat capacity for these materials is not so large to use the reservoir.
From these results, it is concluded that the improvement of the atmospheric resistance of HoPb_2 is necessary for application.
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