Crystal structure and magnetic properties of (Nd,Tb)2Fe14B nanoflakes prepared by surfactant-assisted ball milling

The microstructure, crystal structure, and magnetic properties were studied for (Nd,Tb)2Fe14B nanoflakes prepared by surfactant-assisted high-energy ball milling (HEBM). Effects of ball-milling time on the c-axis crystallographic alignment, morphology, and magnetic properties of (Nd,Tb)2Fe14B nanoflakes were systematically investigated. X-ray diffraction (XRD) results indicate that the average crystal grain size of the nanoflakes decreases from 60 nm of 1 hour milling to 33 nm of 7 hours milling. The nanoflakes milled for 3 hours bear an average thickness of 100 nm and an average diameter of 2 μm leading to a high aspect ratio of 20. In addition, the intensity ratio of I(006)/I(105) indicates that the degree of c-axis crystal texture increases first, peaks for 3 hours, then drops with increasing the milling time. Meanwhile, the coercivity (Hc) of the nanoflakes drops monotonically. The remanence (Mr) of nanoflakes milled for 3 hours in the easy axis direction is 11 kG, while the Mr in the hard axis direction is 1.8 kG, indicating a strong magnetic anisotropy. The optimal magnetic properties of Mr of 11 kG, and Hc of 7 kOe, (BH)max of 24.7 MGOe have been achieved.