Tuning Intrinsic Magnetic Properties of Sm(Fe1-xCox)10V2 Compounds with ThMn12-type Structure

The development of high-performance ThMn12-type SmFe12 based permanent magnets is limited by an intrinsic trade-off between the thermodynamic stability of the 1:12 phase and its magnetic performance. While stabilizing elements such as vanadium are essential for phase formation, they often dilute the magnetic properties. In this work, we demonstrate a strategy to overcome this limitation by systematically investigating the dual role of cobalt (Co) substitution in V-stabilized Sm(Fe1-xCox)10V2 compounds. It is revealed that a moderate Co content (x {less than or equal to} 0.2) not only enhances the intrinsic magnetic properties but also improves the phase stability. The optimal composition, Sm(Fe0.8Co0.2)10V2, exhibits a significant improvement across all key metrics: its ThMn12 phase purity reaches a maximum of 99.1 wt.%, its Curie temperature(TC) is elevated by 110 K to 735 K, and its saturation magnetization(Ms) peaks at 96 emu/g. This behavior is attributed to Co's dual function as both a structural purifier, which suppresses α-Fe impurity formation, and a magnetic enhancer, which strengthens the interatomic exchange interactions. Furthermore, the optimized sample exhibits superior magnetic homogeneity, evidenced by the steepest initial magnetization curve. This work clarifies how Co substitution simultaneously improves phase stability and magnetic performance in V-stabilized Sm-Fe systems. The findings provide guidance for the rational design of next-generation rare-earth-lean magnets with optimized properties.