A novel preparation method and magnetic properties of NaZn_(13)-type La(Fe, Si)_(13) compounds

摘要

The single-phase NaZn_(13)-type La(Fe,Si)_(13) compounds have been successfully synthesized by using a novel stoichiometry chemical ratio 1:11 of La and (Fe, Si). By this method, the as-cast compounds directly formed into NaZn_(13)-type single phase from arc-melting when the Si content in the range of 2.2 to 2.4, which is the first time to obtain NaZn_(13)-type single phase without any heat treatments. Meanwhile, when the Si content x ≤ 1.4, all the compounds crystallize in the NaZn_(13)-type cubic structure with small amounts of α-Fe impurity phase after annealed at 1373 K for 100 h. Among them, the LaFe_(9.8)Si_(1.2) compound shows a thermal and field-induced first-order phase transition around its transition temperature. Its maximal magnetic entropy-change reaches to 14.8 J/kg K under a field change of 1.5 T, showing an excellent magnetic refrigeration property. Thus, the chemical ratio of 1:11 as a new stoichiometry provides a novel and rapid preparation method for single-phase NaZn_(13)-type La(Fe,Si)_(13) compounds with excellent properties.