An indirect approach based on Clausius–Clapeyron equation to determine entropy change for the first-order magnetocaloric materials

• ΔSTΔST can be determined easily and accurately by the CCIF.
• The problem of ΔSTΔST overestimation has been solved by CCIF.
• Fewer M(T)M(T) curves are required for CCIF than MRIF.
• CCIF can be extended to the cases when ΔM   and dTt/dHdTt/dH are not constant.

Taking into account the phase fraction during the structural transition for the first-order magnetocaloric materials, an improved isothermal entropy change (ΔSTΔST) determination has been put forward based on the Clausius–Clapeyron (CC) equation. It was found that the ΔSTΔST value evaluated by this method is in excellent agreement with those determined from the Maxwell relation (MR) using magnetic measurements for some Heusler alloys with a weak field-induced phase transforming behavior, such as Ni–Mn–Sn Heusler alloys. In comparison with the MR based on isofield magnetization measurements (MRIF), this method is very convenient to obtain the ΔSTΔST derived from only few thermomagnetic curves. More importantly, it is quite superior to the MR-based method in eliminating the overestimation of ΔSTΔST due to the appearance of the spurious spike derived from MR employing isothermal magnetization measurements (MRIT).