Effect of Ball-Milling on Magnetic Properties of Uniaxial Nanocrystalline $$\hbox{SmNi}_2 \hbox{Fe}$$ SmNi 2 Fe Compound

Abstract

We report an interesting structural and nanostructural correlation to the Curie temperature and coercivity, respectively. The effect of Ni substitution and magnetocaloric effect (MCE) response for the uniaxial nanocrystalline $$\hbox{SmNi}_2\hbox{Fe}$$ compound was demonstrated. The nanocrystalline SmNi2Fe( $$\hbox{SmNi}_2\hbox{Fe}$$ ) powder has been synthesized by mechanical milling for the first time. The nanocrystalline $$\hbox{SmNi}_2\hbox{Fe}$$ powder has been synthesized by mechanical milling. The structural properties have been studied by x-ray diffraction and have been refined with the Rietveld method. This analysis reveals that the samples crystallize in the rhombohedral PuNi $$_3$$ -type structure ( $$R\bar{3}m$$ -space group). The Curie temperature of $$\hbox{SmNi}_2\hbox{Fe}$$ material is about 450 K. It is a direct measure of the exchange interaction, which is the origin of ferromagnetic phase transition. This interaction depends markedly on the interatomic distance. The magnetic entropy change $$\Delta S_{\mathrm{M}}$$ , as well as the relative cooling power around the second-order magnetic transition and the Arrott plots for the compound have been reported. It was estimated from isothermal magnetization curves, and it decreases with the increase of Fe content from 2.3 J/kg K ( $$x = 0$$ ) to 0.6 J/kg K ( $$x = 0.8$$ ) at 50 kOe. The compound presents high coercivity exceeding 12 kOe at room temperature, obtained based on the optimization of $$\hbox{SmNi}_2\hbox{Fe}$$ nanostructure. The objective of this optimization is to obtain a homogeneous nanostructure developed by the mechanical milling process, subsequent annealing and to the high uniaxial magnetocrystalline anisotropy.