Tunable thermal hysteresis in MnFe(P,Ge) compounds

Abstract

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Microstructure, magnetic and magnetocaloric properties of Fe2–x Mn x P0.4Si0.6 alloys

“…The SOMT becomes obviously with increasing Mn content. This result is in agreement with previous study [13].…”

“…This is the main reason for the linear decr- ease of Tc in the Fe2-xMnxP0.4Si0.6 alloys with increasing Mn content. A more detailed analysis of the lattice parameters confirms that the c/a ratio increases with increasing the Mn/Fe ratio in alloys without minor impurity phase, which also results in a decrease in Tc [13]. However, c/a ratio does not increase continuously with the increasing Mn content in our experimental results, which indicates that this rule is not suitable for the alloys containing impurity phase.…”

“…Magnetization measurements were carried out by using a Lakeshore 7407 type vibrating sample magnetometer (VSM). The direct measurement of the adiabatic temperature change was carried out in a homemade magnetocaloric effect measuring device under a magnetic field of 1.48 T. In this apparatus, sintered Nd-Fe-B permanent magnets were assembled to generate a static magnetic-field, which worked as the magnetic field source in the measurement [13]. Experimental errors for the direct measurement technique were estimated to be ± 0.1 K [20,21].…”

“…Recently, some meaningful studies have been done to reduce the ΔThys for MnFe(P,Ge) and MnFe(P,Si) compounds. For Mn2-yFeyP0.75Ge0.25 compounds, their ΔThys can be reduced to 1.0 K by changing the Mn/Fe ratio and maintain a large maximum isothermal magnetic-entropy change (-ΔSmax) 20 J (kg K) -1 in a field change of 0-2 T around room temperature [13]. MnFe(P,Si) compounds also show giant MCE with a large -ΔSmax of 12.8-18.3 J (kg K) -1 in a field change of 0-2 T and a lager maximum adiabatic temperature change ( T ad max ) of 2.2 K in a field change of 0-1.1 or 0-1.48 T [14][15][16][17].…”

“…Magnetic refrigeration based on magnetocaloric effect (MCE), is an isothermal magnetic-entropy change (-ΔSm) or an adiabatic temperature change (ΔTad) for a magnetic material upon application of a magnetic field [4]. The current investigation of the room temperature MCE mainly focuses on the first-order magnetic phase transition (FOMT) materials, such as Gd5(Ge1-xSix)4, La(Fe1-xSix) 13 and their related compounds, MnAs1-xSbx, MnFeP1-xAsx and MnCoGeBx [5][6][7][8][9][10]. These materials exhibit large -ΔSm in the vicinity of the magnetic-phase transition from a paramagnetic state to a ferromagnetic state.…”