Impact of W doping on Fe-rich (Mn,Fe)2(P,Si) based giant magnetocaloric materials
Fengqi Zhang, Sebastian Smits, Anika Kiecana, Ivan Batashev, Qi Shen, Niels van Dijk, E. Brück
Abstract
The influence of doping with the 5d transition metal W has been studied in the quaternary (Mn,Fe)2(P,Si) based giant magnetocaloric compounds, which is one of the most promising systems for magnetic refrigeration. It is found that W substitution can separately decrease the Curie temperature TC and retain the thermal hysteresis ∆Thys at an almost constant level (∼5 K) for Mn0.6Fe1.27-xWxP0.64Si0.36 (x ≤ 0.02). Low-content W doping conserves the good magnetocaloric effect (MCE) without an obvious degradation. For x ≤ 0.02 the average magnetic entropy change |∆Sm| amounts to 11.4 Jkg−1K−1 for an applied magnetic field change of 2 T and the adiabatic temperature change ∆Tad amounts to 3.9 K for an applied magnetic field change of 1.5 T. The occupancy of substitutional W atoms is determined by XRD experiments and DFT calculations. Our studies provide a good strategy to further optimize the MCE of this material family.