Investigation of the magnetic properties of Dy doped Nd-Fe-B permanent magnet by using Mössbauer spectroscopy

The crystal and the magnetic properties of (Nd 35.00- x Dy x )Fe bal . Cu 0.15 Co 1.50 Al 0.20 Nb 0.35 B 1.00 (wt.%; x = 3.50, 6.00, and 8.00) samples are investigated by using x-ray diffractometer (XRD), vibrating smple magnetometer (VSM), and Mössbauer spectrometer. The crystal structure is determined to be tetragonal with the P 4 2 / mnm space group. The saturation magnetization ( M s ) decreases while the coercivity ( H c ) increases with increasing Dy ion concentration. Based on the zero-filed-cooled (ZFC) curves, all the samples show spin reorientation, and the spin-reorientation temperature TSR decreases with increasing Dy ion concentration. The Mössbauer spectra measured at 295 K show decreasing < Hhf > with increasing Dy concentration, and the abrupt changes both in the magnetic hyperfine field ( H hf ) and the electric quadrupole shift ( E Q ) at temperatures around T SR .