A unique synthesis of rare-earth-Co-based single crystal particles by "self-aligned" Co nano-arrays

In this study, anisotropic SmCo₅ magnets were prepared by a distinctive method, which is the high-temperature reductive annealing of Co@Sm₂O₃ with a specially designed nanostructure. High resolution transmission electron microscopy and elemental mapping show that the precursor self-assembly is composed of hcp-structured Co nano-rods with a coherent crystallographic orientation. During high temperature reduction, the Sm₂O₃ shell preserves the original morphology and alignment of these anisotropic Co nano-arrays, providing a template for hcp-structured SmCo₅ single crystal particle synthesis. The as-prepared SmCo₅ magnets exhibit well-controlled size and morphology, and a high coercivity of 30.9 kOe at room temperature. No stabilizer coating is necessary to prevent the formation of polycrystals in this synthesis.