X-ray diffraction analysis of the magnetoelastic phase transition in the Mn-Fe-P-Si magnetocaloric alloy

Alexandre Pasko (1) , Andras Bartok (1) , Karim Zehani (2) , Lotfi Bessais (2) , Frederic Mazaleyrat (1) , Martino Lobue (1)

1 SATIE-MME - Matériaux Magnétiques pour l'Energie
2 ICMPE - Institut de Chimie et des Matériaux Paris-Est

Structural characterization of the Mn 1.3 Fe 0.65 P 0.5 Si 0.5 powder is reported. The rare-earth-free magnetocaloric material was prepared by ball milling and solid-state synthesis. X-ray diffraction data were collected in a wide temperature range across the magnetoelastic phase transition. The lattice parameters and volume fractions of the paramagnetic and ferromagnetic phases were determined as functions of temperature using Rietveld fitting. The virgin effect (a delay of the phase transition on first cooling) and associated variation of lattice parameters are analyzed on the assumption of elastic constraints imposed on the paramagnetic phase by the defect structure. A simple Landau model with magnetoelastic coupling illustrates the observed first-order behavior.

Domaines: Science des matériaux [cond-mat.mtrl-sci]

Alexandre Pasko, Andras Bartok, Karim Zehani, Lotfi Bessais, Frederic Mazaleyrat, et al.. X-ray diffraction analysis of the magnetoelastic phase transition in the Mn-Fe-P-Si magnetocaloric alloy. AIP Advances, 2016, 6 (5), pp.056204. ⟨10.1063/1.4943245⟩. ⟨hal-01690149⟩