Correlation between Microstructure and Magnetism in Ball-Milled SmCo5/α-Fe (5%wt. α-Fe) Nanocomposite Magnets

Anna Bajorek; Paweł Łopadczak; Krystian Prusik; Maciej Zubko

doi:10.3390/ma14040805

Correlation between Microstructure and Magnetism in Ball-Milled SmCo₅/α-Fe (5%wt. α-Fe) Nanocomposite Magnets

Materials (Basel). 2021 Feb 8;14(4):805. doi: 10.3390/ma14040805.

Authors

Anna Bajorek^{1

2}, Paweł Łopadczak^{1

2}, Krystian Prusik^{2

3}, Maciej Zubko^{2

3}

Affiliations

¹ A. Chełkowski Institute of Physics, University of Silesia in Katowice, 75 Pułku Piechoty 1, 41-500 Chorzów, Poland.
² Silesian Center for Education and Interdisciplinary Research, University of Silesia in Katowice, 75 Pułku Piechoty 1A, 41-500 Chorzów, Poland.
³ Institute of Materials Science, University of Silesia in Katowice, 75 Pułku Piechoty 1A, 41-500 Chorzów, Poland.

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.

Keywords: electronic structure; exchange coupling; high-energy ball milling; magnetic properties; microstructure; permanent magnets; rare-earth intermetallics; soft/hard magnetic nanocomposites.