Magnetic properties and X-ray structure analyses of Nd–Co–B amorphous alloys

A series of Nd16.7Co83.3−xBx (10≦x≦40) amorphous alloys were prepared by melt spinning and their atomic structures were investigated by conventional X-ray diffraction (XRD). The radial distribution functions (RDFs) of the alloys are mainly described by Co–Co, Co–Nd and Nd–Nd partial correlations. By fitting Gaussian functions to an experimental RDF with a nonlinear least-squares method, the structural parameters such as interatomic distances and coordination numbers for the partial correlations were determined. These parameters changed characteristically with the B content. Magnetic measurements for these alloys were performed using a SQUID magnetometer. Magnetization curves were measured at 2 and 300 K, and the temperature dependence of the magnetization was monitored. At 300 K, these alloys were soft magnetic with very small coercive forces for x≦22, while paramagnetic for x>22. On the other hand, at 2 K, they were hard magnetic irrespective of x, and the coercive force took a maximum value of 716.2 kA/m (~9 kOe) for x=25. A correlation between the structural parameters and the magnetic properties was discussed.