Effects of thermal cycling on the thermal and magnetic response of Ni–Mn–Sn–Pd alloys

Abstract

Magnetic refrigeration is an option to replace conventional refrigeration. There are many studies that analyze materials with magnetocaloric effect during the first cooling-heating cycle, without analyzing the influence of cycling (necessary to check its applicability). In this work, we proceed to analyze the crystallographic structure (X-Ray diffraction) and the thermal (differential scanning calorimetry) and thermomagnetic (PPMS cycles and ZFC–FH–FC scans) response after a hundred thermal cycles of two Heusler alloys, Ni49Mn36Sn14Pd1 and Ni48Mn36Sn14Pd2 (at.%), that have been produced by melt spinning as ribbon flakes. In order to check its stability from cycling, these ferromagnetic alloys have been subjected to a hundred of thermal cycles (heating/cooling to provoke the austenite to martensite reversible transformation. The comparison before and after cycling behavior allow us to state that the reduction of the crystallographic defects favors higher atomic order. Likewise, the thermodynamic parameters (entropy and enthalpy) and the magnetic response have been reduced at about 10–12%