| Project/Area Number |
07555493
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 展開研究 |
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| Research Field |
Structural/Functional materials
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| Research Institution | Tohoku University |
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Principal Investigator |
ABE Shunya Tohoku Univ., Institute for Materials Research, Researcher, 金属材料研究所, 助手 (00005901)
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| Co-Investigator(Kenkyū-buntansha) |
SAKATSUME Shinichi Tohoku Univ., Institute for Materials Research, Assistant Professor, 金属材料研究所, 助教授 (20005896)
KANOMATA Takeshi Tohoku Gakuin Univ., Fakulty of Engineering, Professor, 工学部, 教授 (60048816)
YOSHIDA Hajime Tohoku Univ., Institute for Materials Research, Researcher, 金属材料研究所, 助手 (90005950)
MORITA Hiroaki Yamagata Univ., Faculty of Engineering, Professor, 工学部, 教授 (50005914)
FUJIMORI Hiroyasu Tohoku Univ., Institute for Materials Research, Professor, 金属材料研究所, 教授 (60005866)
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| Project Period (FY) |
1995 – 1997
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| Project Status |
Completed (Fiscal Year 1997)
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| Budget Amount *help |
¥2,900,000 (Direct Cost: ¥2,900,000)
Fiscal Year 1997: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 1996: ¥1,700,000 (Direct Cost: ¥1,700,000)
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| Keywords | Rare Earth Intermetallic Compounds / Low Temperature Specific Heat Anomaly / Regenerator / Magnetic Order-Disorder Phase Transition / Magnetic Order-Order Phase Transition / 比熱装置 / 秩序-秩序相転移 / 極低温小型冷凍機 / 蓄熱材 / 相転移 |
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| Research Abstract |
1 Magnetic susceptibilities are measured for the rare earth intermetallic compounds of ErAg, HoAu_2, ErAu_2 and Er_2Au. As for the compounds of HoAu_2 and Er_2Au, it is found that temperature dependence of the susceptibilities make anomalies other than those found previously. These anomalies suggest the existence of new magnetic order-order transitions in these compounds.
2 Specific heats of these compounds except for Er_2Au are measured between 2 and 30 K.ErAg : Mother anomaly is found at a temperature just below the Noel temperature (T_N), where the susceptibility anomaly is not observed. The peak value of specific heat is obtained to be about 20 J・K^<-1>・mol^<-3> (0.7 J・K^<-1>・cm^<-3>) at T_N. HoAu_2 : A peak in the specific heat is observed at the temperature where the new anomaly is found in susceptibility mentioned above. The specific heat at T_N has a peak value of 10 J・K^<-1>・mol^<-3> (0.27 J・K^<-1>・cm^<-3>). ErAu_2 : The maximum value of specific heat at T_N is 13 J・K^<-1>・mol^
… More
<-3> (0.36 J・K^<-1>・cm^<-3>). Er_2Au : A jump of specific heat per unit volume at T_N is roughly estimated to be about 1.5 times of that of ErAg on the basis of molecular field approximation.
3 The specific heats of ErAg, HoAu_2 and ErAu_2 per unit volume below 10 K are found to be lower than that of He gas which is used as a working substance of low-temperature refrigerator, It is found that the specific heats per unit volume of the compounds at temperatures below 10 K are higher than that of lead used generally for a regenerator (below 17 K in the case of ErAg). Therefore, it may be probable to make a regenerator from composite materials of these compounds and lead, so as to discharge heat of He gas below 10 K mainly to these compounds and above 10 K mainly to lead. As for the compound Er_2Au, a jump of specific heat per unit volume, which is estimated to be more than a half of the peak value of the specific heat of He gas at about 8 K, is expected around the same temperature range (T_N=6.2 K). Less
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