The crystal structure, magnetic and magnetocaloric properties of Mn8−xCrxGa5

Mn8Ga5 alloy has certain significance in the study of materials for magnetic refrigeration applications due to its low coercivity. In this paper, the structure, magnetic properties and magnetocaloric effects (MCE) of Mn8−xCrxGa5 (x = 1.3, 1.7) polycrystalline alloys were first studied by using X-ray diffraction (XRD) technique, scanning electron microscope (SEM), energy-dispersion (EDS) analysis and magnetization measurement. The two samples crystallized in a cubic (Zn8Cu5)-type structure with space group of I-43 m (No. 217). The lattice constants and crystallite sizes of Mn8−xCrxGa5 increase with the increase of Cr concentration. As the Cr content increases, the Curie temperature (Tc) of Mn8−xCrxGa5 (x = 1.3, 1.7) is increased from 145 to 187 K. The saturation magnetic moments of Mn8−xCrxGa5 are 33.8 (x = 1.3) and 36.6 (x = 1.7) emu/g under the magnetic field of 16 kOe at 80 K, respectively. A second-order magnetic phase transition occurred in Mn8−xCrxGa5 alloy samples. The maximum magnetic entropy changes (|∆SM|) of Mn8−xCrxGa5 are 0.9 (x = 1.3) and 0.8 J·kg−1·K−1 (x = 1.7), and the relative cooling power (RCP) values are 25 (x = 1.3) and 17 J/kg (x = 1.7) under 15 kOe magnetic field.