Chemically synthesizing exchange‐coupled SmCo 5 /Sm 2 Co 17 nanocomposites

A new strategy to chemically synthesize exchange‐coupled SmCo 5 /Sm 2 Co 17 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/Sm 2 O 3 (Sm to Co atomic ratio of Sm/Co = 1:4.2), which can be reduced into 40‐nm SmCo 5 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·m 2 ·g −1 . By changing the Sm/Co to 1:4.5, 1:4.8 and 1:5.2, SmCo 5 /Sm 2 Co 17 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, SmCo 5 /Sm 2 Co 17 (Sm/Co = 1:5.2) exhibits a coercivity of 1.23 T and enhanced M 7T (magnetization at 7 T) of 0.0812 A·m 2 ·g −1 , increasing by 21% than pure SmCo 5 . Our synthesis provides a new protocol to prepare exchange‐coupled high‐performance nanocomposites.