Crystal structure change in magnetocaloric compounds (Er,Nd)$_2$Fe$_1$$_7$
Résumé
Numerous research studies have documented materials exhibiting a significant magnetocaloric effect (MCE) at elevated temperatures. However, there is a scarcity of materials displaying both intriguing MCE and a second-order transition phase from a ferromagnetic state to a paramagnetic state at approximately 300 K. In this current study, we provide an account of the structural, magnetic, and magnetocaloric characteristics of the (Er,Nd)2Fe17 system. (Er,Nd)$_2$Fe$_1$$_7$ compound was prepared by arc melting under high pure argon and homogenized at 1073 K to minimize the amount of other possible impurity phases. X-ray diffraction (XRD) coupled with Rietveld analysis with FullProf computer code was used for the structural study. This compound crystallizes in the rhombohedral Th$_2$Zn$_1$$_7$ and Th$_2$Ni$_1$$_7$ type structure. The Er$_2$$_−$$_x$Nd$_x$Fe$_1$$_7$ compounds adopt the hexagonal Th$_2$Ni$_1$$_7$-structure type and extends for x = 0, 0.4, 0.7, while for x = 1.75, 1.85 and 2 adopts the rhombohedral Th$_2$Zn$_1$$_7$-structure type. Hence, the temperature dependence of the magnetization is determined. The Curie temperature increases from 294 K to 335 K after the total Er substitution by Nd. The magnetic entropy changes ∆S$_M$, and the relative cooling power and temperature-averaged entropy change (TEC) are reported. Based on these results, the compounds under investigation exhibit an intriguing magnetocaloric effect in the vicinity of room temperature
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