LaFe_(11.2)Co_(0.7)Si_(1.1)合金在室温区的巨大磁熵变

VERY LARGE MAGNETIC ENTROPY CHANGE NEAR ROOM TEMPERATURE IN LaFe_(11.2)Co_(0.7) Si_(1.1)

在具有立方NaZn1 3 型结构的稀土铁基化合物LaFe1 1 2 Co0 7Si1 1 中发现室温区的巨大磁熵变 ,磁熵变的峰值位于居里温度TC=2 74K处 ,5T外磁场下达到～ 2 0 3J kgK ,约为相同的温区下金属Gd的 2倍 .LaFe1 1 2 Co0 7Si1 1 合金中强烈的磁弹性耦合 ,导致晶格在居里温度处出现巨大负膨胀 ,这是其巨大磁熵变的来源 .

Very large magnetic entropy change has been observed in the Fe-based cubic NaZn 13 -type compound LaFe 11.2 Co 0.7 Si 1.1 near the Curie temperature T-C of 274K. The value of this change is ～20^3J/kg K under a magnetic field of 5T at T-C=274K, which markedly exceeds that of pure Gd by a factor of 2 in the corresponding temperature range. The strong structural and magnetic interplay in the compounds, characterized by the drastic lattice contraction at T-C, is presumably responsible for this great entropy change.