Improving the Magnetocaloric Performance of NiMnSnB Heusler Alloys with V Substitutions

The effects of V addition on the structural, magnetic, and magnetocaloric properties in Ni49-xVxMn37Sn12B2 (x = 0, 1, 2, and 3) alloys were investigated. XRD analyses performed at room temperature showed that the main sample was in martensite phase, while x = 3 sample was in L2(1) structure which is attributed to austenite phase. The samples exhibited a first-order structural transformation from austenite phase to martensite phase. The martensitic transformation (MT) temperature was reduced by increasing the amount of V. Besides, V doping caused an increase in magnetization. Although antiferromagnetic interactions arising from Mn-Mn couplings were effective at low temperatures, they vanished above the blocking temperature. Magnetic entropy change (Delta S-M) of the samples was estimated using the Maxwell equation from isothermal magnetization curves. An inverse magnetocaloric effect was observed around the MT interval and Delta S-M was significantly improved with increasing V content and applied magnetic field. Maximum refrigerant capacity (RC), which is one of the quality parameters for characterizing a magnetic refrigerant, was determined as 96.7 J/kg for x = 3 samples (Delta H = 5 T).

Automated summary

The effects of V addition on the structural, magnetic, and magnetocaloric properties in Ni49-xVxMn37Sn12B2 alloys were investigated. V doping reduced the martensitic transformation temperature, increased the magnetization, and significantly improved the magnetic entropy change of the samples.