Tuning Magnetocaloric Effect to Near-Room Temperature for MnCo1−xGe0.5Si0.5 Alloys

The near-room-temperature magnetocaloric materials, i.e., non-stoichiometric MnCo1−xGe0.5Si0.5 (x = 0, 0.025, 0.050, 0.075, and 0.100) alloys with Co atom vacancies, were investigated. The crystal lattice parameters increased as the Co content decreased. The Curie temperatures decreased from high-temperature (393 K) to near-room-temperature (320 K) values as x increased from 0 to 0.100. In an applied magnetic field of 0 to 2 T, the maximum isothermal magnetic entropy change (|ΔSM|) for the MnCo1−xGe0.5Si0.5 alloys was 1.5, 1.7, 2.1, 1.7, and 1.9 J/kg K, while the refrigeration capacity (RC) was 46, 62, 62, 62, and 74 J/kg for x = 0, 0.025, 0.050, 0.075, and 0.100, respectively. Thus, a 27% increase in |ΔSM| and a 60% increase in RC are observed for x = 0.100.