Structural and magnetic properties of magnetocaloric LaFe13–xSix compounds synthesized by high energy ball-milling

The structural and magnetic properties of the LaFe11.3Si1.7 alloy synthesized by arc-melting and the LaFe13–xSix (x = 1.4, 1.6, 1.8, 2.0) series synthesized by high energy ball-milling (BM) have been investigated. The X-ray diffraction (XRD) results show that an almost single 1:13 phase is obtained by BM. No secondary LaFeSi phase was observed for ball-milled samples, which is not the case for the arc-melting synthesis. Moreover, only 30 min of heat treatment are needed for ball-milled LaFe13–xSix alloys in order to obtain single phase compounds (30 days in the case of arc-melted compounds). The study of the magnetic properties revealed that the Curie temperature increases with the Si content whereas the magnetic entropy variation decreases. The latter are respectively associated with a change of the Fe–Fe exchange energy and a magnetic dilution caused by the substitution of a ferromagnetic element by a diamagnetic one. It is shown in this paper that BM compounds display similar magnetic behavior as the corresponding bulk alloys. This means that this way to prepare LaFe13–xSix compounds with giant magnetocaloric effect is cost-effective.