Developing permanent nanomagnets is a critical step to maximize the magnetic performance for miniaturization of electronic and magnetic devices. Among various permanent magnets, Sm-based nanomagnet (SmCo5 Sm2Co17 Sm2Fe17N3) is a class of the most promising materials due to its large coercivity and high Curie temperature. However, the synthesis of Sm-based nanomagnet is very challenging due to a high reduction potential of Sm3+ (-2.3V). Previous chemical synthesis of reducing SmCo-OH cannot control the size of nanoscale SmCo5, which decreases their magnetic performance. Herein, we report a new chemical strategy of SmCo5 nanoparticles (NPs) synthesis. The size of particles can be adjusted from 50 nm to 200 nm with good control. First, we prepared 100 nm flower shape SmCoO NPs from organic solution by thermal decomposition of Sm(acac)3 and Co(acac)3 (acac=acetoacetate). After a calcium oxide coating and high temperature (850oC) reductive annealing, 100 nm crystalline SmCo5 NPs were obtained with a coercivity of 31kOe. By changing the concentration of Sm and Co precursor, 50 nm and 200 nm SmCo5 NPs can also be obtained. By simply adjusting the ratio of Sm(acac)3 to Co(acac)3, pure hexagonal-structured Sm2Co17 NPs can be synthesized. If the Co(acac)3 precursor was replaced by Fe(acac)3, Sm2Fe17 NPs were obtained and further can be nitrogenized to Sm2Fe17N3. The method provides a general synthesis route of high-performance Sm-based nanomagnet.

General way to synthesize Sm-based nanomagnet

256th National Meeting (2018)

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