Chemically synthesizing exchange-coupled SmCo5/Sm2Co17 nanocomposites.

A new strategy to chemically synthesize exchange-coupled SmCo₅/Sm₂Co₁₇ nanocomposites by in situ decomposition of SmCo_x (5 < x < 8.5) is reported in this work. Our synthesis starts with the fabrication of Co/Sm₂O₃ (Sm to Co atomic ratio of Sm/Co = 1:4.2), which can be reduced into 40-nm SmCo₅ single crystal nanoparticles by Ca under the protection of CaO, showing a high coercivity of 2.85 T and saturation magnetization (M_s) of 0.0671 A·m²·g⁻¹. By changing the Sm/Co to 1:4.5, 1:4.8 and 1:5.2, SmCo₅/Sm₂Co₁₇ nanocomposites with different proportions were acquired using the same process. Owing to the in situ decomposition of SmCo_x intermediate, the small size (both of their size less than 10 nm) and uniform phase distribution were achieved in our nanocomposites. Thus, the as-prepared nanocomposites display a strong exchange-coupling interaction. As a consequence, SmCo₅/Sm₂Co₁₇ (Sm/Co = 1:5.2) exhibits a coercivity of 1.23 T and enhanced M_7T (magnetization at 7 T) of 0.0812 A·m²·g⁻¹, increasing by 21% than pure SmCo₅. Our synthesis provides a new protocol to prepare exchange-coupled high-performance nanocomposites. The exchange-coupled SmCo₅/Sm₂Co₁₇ nanocomposites with small size (both of their size less than 10 nm) have been chemically synthesized by in situ decomposition of SmCo_x (5 < x<8.5), which exhibits a coercivity of 1.23 T and enhanced M_s, increasing by 21% than pure SmCo₅. [ABSTRACT FROM AUTHOR]