Preparation and magnetocaloric performance of La(Fe,Co,Si)13 alloys with wide transition temperature range

NaZn13-type La(Fe,Si)13 alloys are one of the most promising magnetocaloric materials for room-temperature magnetic refrigeration. However, the narrow ferromagnetic-to-paramagnetic transition temperature range of La(Fe,Si)13 alloys severely limited their magnetic refrigeration application. Herein, a series of La1.4Fe11.8-xCoxSi1.2 (x = 0.88, 0.94, 0.98, 1.02, 1.06) alloys were designed and prepared by high-energy ball milling and annealing. It is discovered that all the samples are composed of La(Fe,Co,Si)13 main phase and a small amount of α-Fe phase. The Curie temperature of the ferromagnetic-to-paramagnetic transition was well adjusted to room temperature by optimizing the x. A maximum magnetic entropy change (-ΔSM) of 4.0 J kg−1 K−1 for the sample with x = 0.98 was obtained at a magnetic field of 2 T. Meanwhile, all the samples exhibit a significant increase in the half-height width of -ΔSM reaching approximately 35 K, increased by more than 41% compared with that of the reference sample prepared by arc melting. The broadened temperature range originates from the lattice distortion induced by the ball milling process. Our work indicates that La(Fe,Si)13 alloys with relatively large -ΔSM and wide transition temperature range can be simultaneously obtained around room temperature by optimizing the composition and the ball milling process. •A series of La1.4Fe11.8-xCoxSi1.2 alloys were prepared by the high-energy ball milling and annealing treatment.•The -ΔSM of the sample with x = 0.98 reaches 4.0 J kg−1 K−1 around the room temperature under a magnetic field of 2 T.•All the samples exhibit a significant increase in δTFWHM reaching approximately 35 K due to the lattice distortion induced by the ball milling.