Development and application of rare earth intermetallic compounds to working substances for extremely low-temperature refrigerator of small size

稀土金属间化合物在小型极低温制冷机工质中的开发与应用

• 批准号: 07555493
• 负责人: ABE Shunya
• 金额: $ 1.86万
• 依托单位: Tohoku University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (A)
• 财政年份: 1995
• 资助国家: 日本
• 起止时间: 1995 至 1997
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07555493/
• 关键词: 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

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

1测量了ErAg、HoAu_2、ErAu_2和Er_2Au稀土金属间化合物的磁化率。对于HoAu_2和Er_2Au的化合物，发现磁化率的温度依赖性产生了不同于以往的反常现象。这些异常表明这些化合物中存在新的磁序-序转变。2这些化合物的比热除了Er_2Au测量2和30 K之间。ErAg：母亲异常被发现在一个温度略低于诺埃尔温度（T_N），磁化率异常没有观察到。在T_N处测得比热峰值约为20 J·K^<-1>·mol^<-3>（0.7 J·K^<-1>·cm^<-3>）。HoAu_2：在磁化率出现新异常的温度下，观察到比热峰。在T_N处的比热具有10 J·K^<-1>·mol^<-3>（0.27 J·K^<-1>·cm^<-3>）的峰值。ErAu_2：在T_N处的最大比热为13 J·K^<-1>·mol^ ...更多信息 <-3>（0.36 J·K^<-1>·cm^<-3>）。Er_2Au：根据分子场近似，估算出单位体积比热在T_N处的跃变约为ErAg的1.5倍。[3]发现ErAg、HoAu_2和ErAu_2的单位体积比热在10 K以下低于作为低温制冷机工质的He气体的比热，据发现，在低于10 K的温度下的化合物的单位体积的比热高于通常用于再生器的铅（低于17 K的情况下的ErAg）。因此，有可能由这些化合物和铅的复合材料制成回热器，从而将低于10 K的He气体的热量主要释放给这些化合物，而将高于10 K的He气体的热量主要释放给铅。对于Er_2Au化合物，在相同温度范围（T_N= 6.2K）内，单位体积的比热将发生跃变，估计约为He气体在8 K时比热峰值的一半以上。少