Phase Formation and Magnetocaloric Effect in La(Fe1-x-Cox)11.2Si1.8 Compounds Prepared by Ball-milling

The samples of La(Fe1-xCox)11.2Si1.8 (x=0, 0.02, 0.04, 0.06) were prepared by ball-milling with elemental powder and LaSi cast master alloys. After sintering at 1423 K for 30 min followed by quenching in water, an almost NaZn13 type single phase was obtained. The study of magnetic properties reveals that the Curie temperature increases with Co content from x=0 to x=0.06 whereas the magnetic entropy change decreases. The alloy of LaFe11.2Si1.8 has a maximum magnetic entropy change ΔSm of 6.5 J/(kg·K) near its Curie temperature under a magnetic field of 0∼1.5 T, while the maximum magnetic entropy change is about 2.1 J/(kg·K) with x=0.06. Furthermore, the magnetization of ball-milled samples exhibits a second-order magnetic transition, which is interesting for magnetocaloric applications