Chemically synthesizing exchange-coupled SmCo5/Sm2Co17 nanocomposites

Abstract

A new strategy to chemically synthesize exchange-coupled SmCo5/Sm2Co17 nanocomposites by in situ decomposition of SmCox (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 (Ms) 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 SmCox 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 M7T (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 SmCox (5 < x<8.5), which exhibits a coercivity of 1.23 T and enhanced Ms, increasing by 21% than pure SmCo5 .