Abstract
Magnetic nanocomposites SmCo5/α-Fe were synthesized mechanically by high-energy ball milling (HEBM) from SmCo5 and 5%wt. of α-Fe powders. The X-ray diffraction analysis reveals the hexagonal 1:5 phase as the main one accompanied by the cubic α-Fe phase and 2:17 rhombohedral as the secondary phase. The content of each detected phase is modified throughout the synthesis duration. A significant decrease in crystallite size with a simultaneous increase in lattice straining is observed. A simultaneous gradual reduction in particle size is noted from the microstructural analysis. Magnetic properties reveal non-linear modification of magnetic parameters associated with the strength of the exchange coupling induced by various duration times of mechanical synthesis. The highest value of the maximum energy product (BH)max at room temperature is estimated for samples milled for 1 and 6 h. The intermediate mixed-valence state of Sm ions is confirmed by electronic structure analysis. An increase in the Co magnetic moment versus the milling time is evidenced based on the performed fitting of the Co3s core level lines.
Highlights
Nanocomposite permanent magnets have been intensively studied for about two decades due to their possible application in eco-sustainable and energy-saving technologies, leading towards device miniaturization [1,2,3]
Our study aims to bring out a detailed investigation based on the synthesis of SmCo5 /α-Fe nanocomposite nanopowders via modified high-energy ball milling (HEBM)
It is worth mentioning that in X-ray powder diffraction (XRD) patterns, there is no evidence of other impurity traces, namely, from the ZrO2 milling media or samarium oxide
Summary
Nanocomposite permanent magnets have been intensively studied for about two decades due to their possible application in eco-sustainable and energy-saving technologies, leading towards device miniaturization [1,2,3]. A relatively significant coercivity was denoted by Rama Rao et al [53], who found a maximum coercivity of 8.9 kOe in SmCo5 /α-Fe (5 wt.% α-Fe) nanocomposite magnets (a combination of 10 h of milling, consolidation under 2 T magnetic field, SPS in a Materials 2021, 14, 805 vacuum at the sintering temperature 700–740 ◦ C and pressure 10–10.5 kN for 5 min) due to stronger exchange coupling between the hard and soft magnetic phases than evidenced for the 10 wt.% α-Fe-containing sample. The first step in such synthesis was low-energy ball milling and aligning the as-milled specimen in the magnetic field of 1.2 T for 5 min As it was shown, the magnetic coupling between hard and soft phases is maintained after PPC despite the evident soft phase grain growth seemingly beyond the theoretically predicted limits. We present the modification within the electronic structure versus milling, which for the SmCo5 /α-Fe-based nanocomposites is undoubtedly a novelty element
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