Peltier cell calorimetry “as an option” for commonplace cryostats: Application to the case of MnFe(P,Si,B) magnetocaloric materials

Xu, Jun; Guillou, F.; Yibole, H.; Hardy, V.

doi:10.1016/j.fmre.2022.09.020

Cited by 6 publications

(1 citation statement)

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“…Various methods have been investigated to prepare Fe 2 P-type MnFe(P,Si) and MnFe(P,Si,B) magnetocaloric materials including drop synthesis [39], casting [40], arc-melting [41], melt-spinning [42], and single crystal [43] methods. Yet, until now, a solid-state synthesis after a ball-milling stage remains the most widely used and that yielding among the highest magnetocaloric performances [44]. Systematic investigations on the effect of the sintering temperature and sintering duration have been carried out to optimize the magnetocaloric effect (mostly the isothermal entropy change) in Mn 1.000 Fe 0.950 P 0.595 Si 0.330 B 0.075 [45], MnFe 0.95 P 0.587 Si 0.34 B 0.073 [46] or the sample purity in (Fe,Co) 2 (P,Si) [47] compounds.…”

Section: Introductionmentioning

confidence: 99%

Structure, Microstructure and Magnetocaloric/Thermomagnetic Properties at the Early Sintering of MnFe(P,Si,B) Compounds

Qianbai,

Yibole,

Guillou

2024

Metals

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Minimizing the sintering time while ensuring high performances is an important optimization step for the preparation of magnetocaloric or thermomagnetic materials produced by powder metallurgy. Here, we study the influence of sintering time on the properties of a Mn0.95Fe1P0.56Si0.39B0.05 compound. In contrast to former reports investigating different annealing temperatures during heat treatments of several hours or days, we pay special attention to the earliest stages of sintering. After ball-milling and powder compaction, 2 min sintering at 1100 °C is found sufficient to form the desired Fe2P-type phase. Increasing the sintering time leads to a sharper first-order magnetic transition, a stronger latent heat, and usually to a larger isothermal entropy change, though not in all cases. As demonstrated by DSC or magnetization measurements, these parameters present dissimilar time evolutions, highlighting the existence of various underlying mechanisms. Chemical inhomogeneities are likely responsible for broadened transitions for the shortest sinterings. The development of strong latent heat requires longer sinterings than those for sharpening the magnetic transition. The microstructure may play a role as the average grain size progressively increases with the sintering time from 3.5 μm (2 min) to 30.1 μm (100 h). This systematic study has practical consequences for optimizing the preparation of MnFe(P,Si,B) compounds, but also raises intriguing questions on the influence of the microstructure and of the chemical homogeneity on magnetocaloric or thermomagnetic performances.

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