Low spin reorientation transition temperature, high coercivity, Nd2(Fe,Co,Cr)14B based hard magnetic nanoparticles

We have synthesized high coercivity Nd 2 Fe 10.5 Co 2 Cr 1.5 B magnetic nanoparticles through a green and low cost mechanochemical method. The coercivity (H C ) of isolated Nd 2 (Fe 10.5 Co 2 Cr 1.5 )B nanoparticles and nanoparticles embedded in a CaO matrix was found to be 11.3 kOe and 9 kOe, respectively. The thermal coefficient of remanence (α (Mr)) and coercivity (β (H C )) of these nanoparticles after removal of CaO, measured from room temperature to 400 K, was found to be -0.0015 and -0.0065, respectively. These nanoparticles exhibit the spin reorientation transition temperature (T SR ) of ∼89 K, which is ∼46 K less than that of bulk Nd 2 Fe 14 B magnets, hence, more attractive for cryogenic applications.