Magnetocaloric properties of Mn5Sn3-xGax alloys

We report on the crystal structure and the magnetic properties of Mn₅Sn_3-xGa_x alloys with x=0.1,0.3,0.5,1.0, and 1.5, which were investigated by means of X-ray powder diffraction and magnetization measurements in fields up to 5 T in the temperature range 5 to 360 K. These alloys have in common that they exhibit a temperature-induced ferrimagnetic phase transition. The results indicate that all samples crystallize in the hexagonal Ni₂ In-type structure with space group P6₃/mmc. The lattice parameters a and c of the Mn₅Sn_3-xGa_x decrease with increasing x, while the Curie temperature of these alloys increases with increasing x. All of the alloys exhibit a moderate magnetocaloric effect. Typical values are about 0.8 and 3 J/kgK at T_c=282 K for x=1.5 in a magnetic field change from 0 to 1 T and 0 to 5 T, respectively.