High coercivity Pr(2)Fe(14)B magnetic nanoparticles by a mechanochemical method

Nd(2)Fe(14)B nanoparticles are widely used because of their outstanding hard magnetic properties. In fact, Pr(2)Fe(14)B has higher magneto-crystalline anisotropy than Nd(2)Fe(14)B, which makes Pr-Fe-B a promising magnetic material. However, the chemical synthesis route to Pr(2)Fe(14)B nanoparticles is challenging because of the higher reduction potential of Pr(3+), as well as the complex annealing conditions. In this work, Pr(2)Fe(14)B nanoparticles were successfully synthesized via an efficient and green mechanochemical method consisting of high energy ball milling, annealing, and a washing process. Microstructural investigations revealed that the oxide precursors were uniformly wrapped by CaO and CaH(2), which formed an embedded structure after ball milling. Then, Pr(2)Fe(14)B powder was synthesized via a time-saving annealing process. The impact of the Pr(2)O(3) content and the preparation conditions was investigated. The coercivity of the as-annealed powder with 100 wt% Pr(2)O(3) excess is 18.9 kOe. After magnetic alignment, the coercivity, remanence, and maximum energy product were: 9.8 kOe, 78.4 emu g(−1), and 9.8 MGOe, respectively. The present work provides a promising strategy for preparing anisotropic Pr-Fe-B permanent magnetic materials.