Study of the magnetic and magnetocaloric properties at low-field in Nd2Fe17-xSix intermetallics

[Display omitted] •Nd2Fe17-xSix (x = 0, 0.25 and 0.5) samples have crystallized in the rhombohedral Th2Zn17 type structure (R-3m).•Rietveld refinement on XRD and Mössbauer spectroscopy analysis reveal that the Si atoms substitute Fe in the 18h Wyckoff site.•Tc increases with Si content from 331 K to 366 K for x = 0 and x = 0.5 respectively.•Magnetic entropy variation δS decreases with Si content from 3.35 J/kgK for Nd2Fe17 to 2.50 J/kgK for Nd2Fe16.5Si0.5. Magnetic refrigeration could ultimately allow the replacement of commonly-used industrial coolers or household refrigerators, mainly for its potential great efficiency and ecological factors. In the search of good magnetocaloric materials, the iron rich Nd2Fe17 intermetallics are regarded as very interesting candidates, due to their significant magnetic properties. To that end, three samples with nominal compositions Nd2Fe17-xSix (x=0,0.25,0.5) were prepared by using an arc furnace, followed by annealing. Structural analysis by Rietveld method on X-ray diffractograms have shown that these alloys crystallize in the rhombohedral Th2Zn17-type structure (Space group R3¯m) and that Fe is being substituted by Si in the 18h Wyckoff position. Magnetic properties measurements revealed that the Curie temperature increases while the magnetization at saturation diminishes with Si content. The magnetic entropy change ΔSM reached a maximum of 3.35 J/kg.K, 2.77 J/kg K and 2.50 J/kg K for an applied field of 1.5 T for x = 0, 0.25 and 0.5 respectively, pointing to a decrease with Si content. The RCP seems however to receive an extensive boost from the Fe to Si substitution. Mössbauer spectra analysis was also performed, in order to confirm the site 18h as the location of Si atoms in Nd2Fe17-xSix and the magnetization at saturation.