Magnetocaloric and barocaloric effects associated with two successive magnetostructural transformations in Ni55.5Mn17.8Ga26.7 alloy.

The structural, magnetic, magnetocaloric and barocaloric properties were investigated in Ni 55.5 Mn 17.8 Ga 26.7 alloy. The results show that the sample experiences two successive magnetostructural transformations (MSTs) with decreasing/increasing temperature. The field-induced entropy change and pressure-induced entropy change are only −7.55 J/kg K for a field change of Δ H = 3 T and −10.52 J/kg K for a pressure change of Δ P = 0.622 GPa while the corresponding refrigeration capacity (RC) achieves 68.80 J/kg and 247.83 J/kg, respectively. Such considerable RC values can be ascribed to the broadening of the full-width at half maximum (FWHM) due to the two successive MSTs. It was observed that RC and FWHM increase with magnetic field and pressure, which results in an enhancement of magnetocaloric and barocaloric effects. Importantly, RC and FWHM under Δ P = 0.622 GPa are comparable to and even larger than those reported in some expensive rare-earth-based magnetic refrigerants. The responses of RC and FWHM to pressure are 89.05 J/kg GPa and 4.77 K/GPa for 0 ≤ P ≤ 0.3 GPa and the values are 654.57 J/kg GPa and 73.86 K/GPa for 0.3 ≤ P ≤ 0.622 GPa. The FWHMs of 11.23 K under Δ H = 3 T and of 32.83 K under Δ P = 0.622 GPa are obtained. All these excellent properties originated from two successive MSTs would make Ni 55.5 Mn 17.8 Ga 26.7 alloy promising as a new and inexpensive multicaloric material used in the solid refrigeration technology. • Ni 55.5 Mn 17.8 Ga 26.7 alloy exhibits two successive magnetostructural transformations (MSTs). • Large magnetocaloric and barocaloric effects were observed due to the two successive MSTs. • Two successive MSTs and hydrostatic pressure can effectively broaden the phase transforming temperature span. • A large refrigerant capacity of 247.83 J/kg was obtained under a pressure change of 0.622 GPa. • An inexpensive multicaloric material Ni 55.5 Mn 17.8 Ga 26.7 alloy was reported. [ABSTRACT FROM AUTHOR]