Impact of F and S doping on (Mn,Fe)2(P,Si) giant magnetocaloric materials

作者：Fengqi Zhang, Ivan Batashev, Qi Shen, Ziying Wu, Ronald I. Smith, G. A. de Wijs, Niels van Dijk, E. Brück · 发表于：Acta Materialia · 年份：2022 · DOI：10.1016/j.actamat.2022.118057 · 被引用次数：26 · 研究领域：Magnetic and transport properties of perovskites and related materials、Thermal Expansion and Ionic Conductivity、Rare-earth and actinide compounds

The quarternary (Mn,Fe)2(P,Si)-based materials with a giant magnetocaloric effect (GMCE) at the ferromagnetic transition TC are promising bulk materials for solid-state magnetic refrigeration. In the present study we demonstrate that doping with the light elements fluorine and sulfur can be used to adjust TC near room temperature and tune the magnetocaloric properties. For F doping the first-order magnetic transition (FOMT) of Mn0.60Fe1.30P0.64Si0.36Fx (x = 0.00, 0.01, 0.02, 0.03) is enhanced, which is explained by an enhanced magnetoelastic coupling. The magnetic entropy change |ΔSm| at a field change (Δμ0H) of 2 T markedly improved by 30% from 14.2 Jkg−1K−1 (x = 0.00) at 335 K to 20.2 Jkg−1K−1 (x = 0.03) at 297 K. For the F doped material the value of |ΔSm| for Δμ0H = 1 T reaches 11.6 Jkg−1K−1 at 294 K, which is consistent with the calorimetric data (12.4 Jkg−1K−1). Neutron diffraction experiments reveal enhanced magnetic moments by F doping in agreement with the prediction of DFT calculation. For S doping in Mn0.60Fe1.25P0.66-ySi0.34Sy (y = 0.00, 0.01, 0.02, 0.03, 0.04) three impurity phases have been found from microstructural analysis, which reduce the stability of the FOMT in the main phase and decrease TC, e.g. the |ΔSm| reduces from 7.9(12.6) Jkg-1K-1 (332 K) for the undoped sample to 3.4(6.2) Jkg-1K-1 (313 K) for the maximum doped sample for Δμ0H = 1(2) T. Neutron diffraction experiments combined with first-principles theoretical calculation, distinguish the occupati...