Hysteresis, latent heat and cycling effects on the magnetocaloric response of (NiMnSi)0.66(Fe2Ge)0.34 alloy. (April 2021)

• Record Type: Journal Article
• Authors: Moreno-Ramírez, L.M.; Díaz-García, Á.; Law, J.Y.; Giri, A.K.; Franco, V.
• Is Part Of: Intermetallics. Volume 131(2021)
• Publication Date: 2021-04
• Subjects: MnNiSi-Based alloys -- Magnetostructural transformations -- Magnetocaloric effect; Intermetallic compounds -- Metallography -- Periodicals; Metallic glasses -- Periodicals; Composés intermétalliques -- Métallographie -- Périodiques; 669.94
• DOI: 10.1016/j.intermet.2020.107083
• Languages: English
• ISSNs: 0966-9795

Abstract

Abstract: In this work, we further analyze the promising magnetocaloric (NiMnSi)0.66 (Fe2 Ge)0.34 alloy, which presents isothermal entropy change values as large as 29 J kg −1 K −1 for 2 T at room temperature. It undergoes a magnetostructural transition accompanied by large thermal/magnetic hysteresis, which remains up to high magnetic fields (corroborated by the elaboration of an experimental magnetic phase diagram). We illustrate that this huge hysteretic behavior (i.e. different responses when magnetizing or demagnetizing) can lead to erroneous interpretation of the order of the phase transition by applying the conventional Banerjee's criterion or the recently developed field dependence analysis of the magnetocaloric effect. Additionally, the cyclability of the response is characterized, showing that after several measurements the magnetocaloric response is significantly reduced (by ≈ 40%) due to sample breaking. These dependences together with the large latent heat of the transition (15.0 kJ kg −1 ) lead to relatively small values of the adiabatic temperature change for powdered samples at moderate field changes, reaching around 0.6 K for 1.75 T by direct measurement methods. Highlights: (NiMnSi)0.66 (Fe2 Ge)0.34 shows large Δ s T values at room temperature. This is accompanied by low reversibility/large hysteresis. Hysteresis can lead to erroneous interpretation of the order of the transition. Cycling effect reduces the magnetocaloric response around 40%. Δ T S is shown to be limited (around 0.6 K at 1.76 T) due to the high latent heat.