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 alpha-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 (-Delta SM) 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 -Delta SM 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 -Delta SM and wide transition temperature range can be simultaneously obtained around room temperature by optimizing the composition and the ball milling process.