Site preferences for La and Pr in Nd2Fe14B permanent magnet: A first principles study

Abstract

Using the first principles method, we studied the site preference and the magnetic ground state of rare-earth elements La and Pr doped Nd2Fe14B permanent magnet. It was found that the La preferred the f-site doping at low doping ratio (12.5 %) while the g-site was more favorable at high doping (25 %). For the Pr impurity, we observed the opposite behavior because the site preference was switched. In addition, the spin configuration also depended on the impurity type and concentration. An antiferromagnetic (AFM) type spin configuration was found at both lower and higher doping ratios of La. For the Pr impurity, at a lower doping ratio, the AFM spin configuration was still preserved. However, the ferromagnetic spin configuration was more stable at a high doping ratio. Through impurity-substitution energy calculations, we found that the La impurity preferred to enter into the 2:14:1 phase at low doping, but it favored the grain-boundary phase at high (25 %) doping ratio. On the other hand, we observed that the Pr always preferred the main phase for both low and high doping concentrations.