Structural, magnetic and magnetocaloric properties of the Gd2Fe17-xCrx (x = 0, 0.5, 1 and 1.5) compounds

Abstract

We have investigated the effect of the substitution of iron by chromium on the structural, magnetic and magnetocaloric behaviors of Gd2Fe17-xCrx (x = 0, 0.5, 1 and 1.5). The Rietveld analysis of the X-ray powder diffraction refinement showed that this substitution leads to an increase of the unit-cell volume. All the compounds show a ferromagnetic to paramagnetic transition at the Curie temperature (TC) from the variation of magnetization vs. temperature. Upon Cr substitution, the Curie temperature decreases from 475 K for x = 0 to a value of 452 K for x = 1.5. Arrott plot analyses were applied for verifying the order of the magnetic transition in this system, which was found to be of second order. Besides, the magnetocaloric effect for the Gd2Fe17-xCrx (x = 0, 0.5, 1 and 1.5) compounds was evaluated by the magnetic entropy change and the related Relative Cooling Power (RCP). In the vicinity of TC, |-ΔSM| reached a maximum value of 1.14 J kg−1 K−1, 1.71 J kg−1 K−1, 2.45 J kg−1 K−1 and 3.40 J kg−1 K−1, although the RCP was found to be 18 J kg−1, 31.9 J kg−1, 42.5 J kg−1 and 51.2 J kg−1 for x = 0, 0.5, 1 and 0.15, respectively in a magnetic applied field of 1.56 T. These results reveal that the Gd2Fe17-xCrx (x = 0, 0.5, 1 and 1.5) compounds are attractive materials that could be used as active refrigerants for the magnetic refrigeration and heat pumping technology above room temperature.