Coercivity enhancement and microstructural optimization in diffusion-processed Ce-Nd-Fe-B-based films

Magnetic properties as well as microstructural evolution were firstly studied in Cr(20 nm)/Ce13Fe79B8(100 nm)/Cr(20 nm) benchmark film and the film diffusion-processed with Ce70Cu30(11 nm), Nd(11 nm) and Nd70Cu30(11 nm) alloy layer. The coercivities were still as low as 0.6 T with poor squareness even after diffusion process. By Nd substitution for Ce in Ce-13 - xNdxFe79B8 magnetic layer, squareness was greatly improved. The coercivity was tunable between 0.6 T and 2.34 T and maximum energy product was ranged from 83.4 kJ/m(3) to 204.6 kJ/m(3) depending on the Nd composition in Cr(20 nm)/ Ce13 - xNdxFe79B8(100 nm)/Nd(11 nm)/Cr (20 nm) (x = 3, 6, 9) films. Transmission electron microscopy observation showed the columnar 2:14:1 phase grains with typical core/shell microstructure and rare-earth-rich grain boundaries. Our results demonstrated the promising commercialization potential of Ce-Fe-B based magnets with performance between ferrites and Nd-Fe-B magnets.