Enhancement of martensite transition temperature and inverse magnetocaloric effect in Ni<inf>43</inf>Mn<inf>47</inf>Sn<inf>11</inf> alloy with B doping

Ni43Mn47Sn11 and Ni43Mn47Sn10.5B0.5 polycrystalline alloys have been prepared by using arc-melting and characterized by X-ray diffraction (XRD), differential scanning calorimetry (DSC), magnetization measurements and microhardness tests. Temperature dependent XRD measurements shows the evolution of monoclinic martensite phase (P12/m1)from the cubic austenite L21 (Fm-3m)phase. An enhancement (73 K)in the martensite transition temperature from 210 K for Ni43Mn47Sn11 to 283 K for Ni43Mn47Sn10.5B0.5 was observed by DSC measurements, which is attributed to the increase in cell volume on the account of B doping. Microhardness measurements showed that the hardness reduces with B doping in Ni43Mn47Sn11 alloy. The magnetic entropy change evaluated from the magnetization measurements was found to be 14 J/kg-K and 17 J/kg-K for Ni43Mn47Sn11 and Ni43Mn47Sn10.5B0.5 alloys respectively. The effective magnetic refrigeration capacity at a maximum field of 5 T was found to be 94 J/kg for Ni43Mn47Sn11 and 55 J/kg for Ni43Mn47Sn10.5B0.5, suggesting that these alloys have potential for magnetocaloric applications (magnetic refrigeration).