Calorimetric investigation of the magnetocaloric effect in Ni45Co5Mn37.5In12.5
Résumé
A calorimetric investigation of a Ni45Co5Mn37.5In12.5 single crystal has been carried out by combining differential scanning calorimetry (DSC) and heat capacity (C) measurements. The martensitic transition showing a first-order character spread over a wide temperature range, a specific measuring technique of C(T) has been developed. This method—based on a time-resolved analysis of successive heating pulses—was found to yield an entropy change at the transition (ΔStr) that is very close to that derived from DSC. To investigate the magnetocaloric effect, both the isothermal entropy change ΔST and the adiabatic temperature change ΔTad were derived from heat capacity curves recorded in a series of magnetic fields up to 7 T. The maximum values of ΔST(T, B) were observed to be in accordance with those determined from the Maxwell equation. Furthermore, maximum values of ΔTad(T, B) resulting from the application of 2 T, 5 T and 7 T were found to be equal to −2.3 K, −6.1 K and −9.4 K, respectively.