Magnetic properties and magnetocaloric effects in NaZn13-type La(Fe, Al)13-based compounds
Magnetic properties and magnetocaloric effects in NaZn13-type La(Fe, Al)13-based compounds
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DOI：
10.1088/1674-1056/22/1/017502
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发表时间：
2012-12
影响因子：
1.7
通讯作者：
B. Shen 沈;F. Hu 胡;Qiao-Yan 巧燕 Dong 董;J. Sun 孙
中科院分区：
文献类型：
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作者：
B. Shen 沈;F. Hu 胡;Qiao-Yan 巧燕 Dong 董;J. Sun 孙
本文综述了原子替代、磁场和温度对LaFe 13 −xAlx化合物磁性和磁热性能影响的研究进展。随着铝含量的增加，化合物依次呈现出反铁磁（AFM）态、铁磁（FM）态和微磁态。此外，LaFe 13 −xAlx的AFM耦合可以通过用Si取代Al，Co取代Fe，磁性稀土R取代La，或引入间隙C或H原子来转换为FM耦合。然而，低掺杂水平导致嵌入AFM基质中的FM簇，并且所得到的化合物可以在适当的施加场下经历首先AFM-FM然后在加热时经历FM-AFM相变，在转变温度附近具有显著的磁弛豫。通过选择合适的Co、C或H含量，LaFe 13 −xAlx的居里温度可以向室温移动，并且在转变温度附近可以获得强的磁热效应。例如，对于LaFe11.5Al1.5C0.2H1.0化合物，在0-5 T的场变化下，最大熵变达到13.8 J·kg-1·K-1，发生在室温附近。它比Gd高42%，因此，该化合物是一种有前途的室温磁制冷剂。
In this article, our recent progress concerning the effects of atomic substitution, magnetic field, and temperature on the magnetic and magnetocaloric properties of the LaFe13−xAlx compounds are reviewed. With an increase of the aluminum content, the compounds exhibit successively an antiferromagnetic (AFM) state, a ferromagnetic (FM) state, and a mictomagnetic state. Furthermore, the AFM coupling of LaFe13−xAlx can be converted to an FM one by substituting Si for Al, Co for Fe, and magnetic rare-earth R for La, or introducing interstitial C or H atoms. However, low doping levels lead to FM clusters embedded in an AFM matrix, and the resultant compounds can undergo, under appropriate applied fields, first an AFM—FM and then an FM—AFM phase transition while heated, with significant magnetic relaxation in the vicinity of the transition temperature. The Curie temperature of LaFe13−xAlx can be shifted to room temperature by choosing appropriate contents of Co, C, or H, and a strong magnetocaloric effect can be obtained around the transition temperature. For example, for the LaFe11.5Al1.5C0.2H1.0 compound, the maximal entropy change reaches 13.8 J·kg−1·K−1 for a field change of 0–5 T, occurring around room temperature. It is 42% higher than that of Gd, and therefore, this compound is a promising room-temperature magnetic refrigerant.