Optimized Copper Distribution and Enhanced Coercivity in PrO ₂ ‐Doped Sm ₂ Co ₁₇ ‐Type Magnets

A rational design of Cu distribution is crucial for achieving optimal magnetic properties in Sm 2 Co 17 ‐type magnets. In this study, nanostructured PrO 2 powders were employed to induce Cu redistribution at grain boundaries while preserving the cellular microstructure. The corresponding coercivity ( H cj ), remanence ( B r ), and maximum energy product (( BH ) max ) were significantly enhanced in the 1 wt% PrO 2 ‐doped magnet, with improvements of 4.36 kOe, 0.22 kGs and 1.1 MGOe, respectively. These results surpass those of most rare‐earth‐oxide‐doped Sm 2 Co 17 ‐type magnets reported to date. Microstructure characterization and micromagnetic simulations confirm that the coarse Cu‐rich phase induced by PrO 2 doping enhances the pinning strength at grain boundaries, thereby contributing to the observed coercivity enhancement. The (Sm 1− x Pr x ) 2 Co 17 phase exhibits a higher substitution energy barrier at Co sites, which promotes Cu migration toward grain boundaries. Meanwhile, the (Sm 1− x Pr x ) 2 Co 17 phase also slightly improves the remanence in the 1 wt% PrO 2 ‐doped magnet due to its higher saturation magnetization ( M s ). However, excessive PrO 2 doping (2 wt%), while further increasing coercivity by 6.45 kOe, adversely affects squareness and remanence. This study demonstrates a viable strategy for fabricating high‐performance Sm 2 Co 17 ‐type permanent magnets while enabling efficient utilization of rare‐earth Pr oxides.