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Study of magnetocaloric effects on rare-earth and iron compounds for room temperature magnetic refrigeration

室温磁制冷稀土和铁化合物的磁热效应研究

基本信息

批准号：
13650719
负责人：
WADA Hirofumi
金额：
$ 2.24万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2002
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-13650719/
关键词：
magnetic refrigeration magnetocaloric effect first-order transition metamagnetism magnetic transition

项目摘要

In recent years, there has been increasing interest in magnetic refrigeration as an environmentally friendly alternative to conventional vapor-cycle refrigeration. The magnetic refrigeration makes use of the cycles of magnetization and demagnetization of a magnetic material, so that the development of new materials with a giant magnetocaloric effect (MCE) is strongly desired. In the previous research project of Grant-in-aid for scientific research (09555185), we have pointed out that the first-order phase transition system would show giant MCEs. In this study, we investigated MCEs of the compounds with T_c at around room temperature. The following results were obtained.1) We started our research from focusing our attention on the compounds with rare-earths and iron. First, We measured the magnetic entropy change, ΔS_M, caused by a magnetic field. Of R_2Fe_<17> compounds (R=Pr, Ce and Ce_<0.5>Nd_<0.5>) and Gd Laves phase compounds (Gd(Co-Ni)_2 and Gd(Al-Fe)_2). However, these compounds … More show at most 6 J/K kg of ΔS_M, at the peak value, which is less than half of that of Gd.2) Then, we searched a first-order phase transition system and found MnAs. This compound shows a first-order ferromagnetic to paramagnetic transition at 317 K. The observed ΔS_M is 32 J/K kg, which is 1.7 times as large as that of Gd_sSi_2Ge_2. These results indicate that MnAs shows giant MCEs. We also found the substitution of Sb for As can tune the Curie temperature between 220 K and 317 K without any significant reduction of MCEs. These results indicate that MnAs_<1-x>Sb_x is one of the most suitable candidates for the magnetic refrigerant material at room temperature.3) During the present research, the Chinese group reported a large MCE of La(FeCoSi)_<13>. However, a detailed magnetic phase diagram was not investigated. We studied the magnetic properties of La(Fe_<0.88>Si_<0.12-x>Co_x)_13. The compounds form a NaZn_<13>-type structure for 0【less than or equal】x【less than or equal】0.05. The Curie temperature is increased from 195 K to 260 K with increasing x from 0 to 0.05. Metamagnetic behavior was observed above T_c in the concentration range of 0【less than or equal】x【less than or equal】0.05. These results suggest large magnetocaloric effects of the present system at around room temperature. Less

近年来，磁制冷作为一种环境友好的替代传统蒸汽循环制冷的方法受到越来越多的关注。磁制冷利用磁性材料的磁化和退磁的循环，使得强烈期望开发具有巨磁热效应（MCE）的新材料。在前期的科研资助项目（09555185）中，我们曾指出一级相变体系会出现巨微元胞效应。本研究中，我们研究了具有室温附近T_c的化合物的MCE。主要研究结果如下：1）我们的研究从稀土铁化合物开始。首先，我们测量了磁场引起的磁熵变ΔS_M。R_2Fe_3<17>化合物（R=Pr，Ce和Ce_<0.5>Nd_3<0.5>）和Gd Laves相化合物（Gd（Co-Ni）_2和Gd（Al-Fe）_2）。然而，这些化合物 ...更多信息在最大值处的ΔS_M最多为6 J/Kkg，小于Gd的一半。2）然后，我们寻找了一个一级相变系统，发现了MnAs。该化合物在317 K时表现出一级铁磁-顺磁转变。观测到的ΔS_M为32 J/K kg，是Gd_sSi_2Ge_2的1.7倍。这些结果表明MnAs显示出巨大的MCE。我们还发现Sb替代As可以在220 K和317 K之间调节居里温度，而没有任何显着的MCE降低。这些结果表明MnAs_<1-x>Sb_x是室温磁制冷材料最合适的候选材料之一。3）在本研究期间，中国小组报告了La（FeCoSi）_的大MCE<13>。然而，没有研究详细的磁相图。研究了La（Fe_<0.88>Si_<0.12-x>Co_x）_13的磁性。该化合物形成NaZn_<13>-型结构，0[小于或等于]x[小于或等于]0.05。随着x从0增加到0.05，居里温度从195 K增加到260 K.在0[小于或等于]x[小于或等于]0.05的浓度范围内，在高于T_c时观察到变磁行为。这些结果表明本系统在室温附近具有较大的磁热效应。少