Transition-metal-based magnetic refrigerants for room-temperature applications
Transition-metal-based magnetic refrigerants for room-temperature applications
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DOI：
10.1038/415150a
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发表时间：
2002-01-10
期刊：
影响因子：
64.8
通讯作者：
de Boer, FR
中科院分区：
文献类型：
--
作者：
Tegus, O;Brück, E;de Boer, FR
基于磁热效应（MCE）的磁制冷技术最近被证明是传统蒸汽循环制冷的一种有前途的替代方案（1）。在显示MCE的材料中，通过外部磁场随机取向的磁矩的对齐导致加热。然后可以通过热传递将该热量从MCE材料移除到环境大气。如果随后关闭磁场，磁矩再次随机化，这导致材料冷却到环境温度以下。在这里，我们报告发现一个大的磁熵变MnFeP0.45As0.55，材料的居里温度约为300 K，并允许在室温下的磁制冷。磁场变化为2 T和5 T时，磁熵变分别达到14.5J·K ~（-1）和18 J·K ~（-1）·kg ~（-1）。所谓的巨MCE材料Gd 5Ge 2Si 2（参考文献2）显示出类似的熵变，但只能在室温以下使用。我们的材料的制冷能力也明显大于Gd（参考文献3）。大的熵变归因于场诱导的一级相变增强了外加磁场的作用。
Magnetic refrigeration techniques based on the magnetocaloric effect (MCE) have recently been demonstrated as a promising alternative to conventional vapour-cycle refrigeration(1). In a material displaying the MCE, the alignment of randomly oriented magnetic moments by an external magnetic field results in heating. This heat can then be removed from the MCE material to the ambient atmosphere by heat transfer. If the magnetic field is subsequently turned off, the magnetic moments randomize again, which leads to cooling of the material below the ambient temperature. Here we report the discovery of a large magnetic entropy change in MnFeP0.45As0.55, a material that has a Curie temperature of about 300 K and which allows magnetic refrigeration at room temperature. The magnetic entropy changes reach values of 14.5 J K-1 kg(-1) and 18 J K-1 kg(-1) for field changes of 2 T and 5 T, respectively. The so-called giant-MCE material Gd5Ge2Si2 (ref. 2) displays similar entropy changes, but can only be used below room temperature. The refrigerant capacity of our material is also significantly greater than that of Gd (ref. 3). The large entropy change is attributed to a field-induced first-order phase transition enhancing the effect of the applied magnetic field.