Hierarchical assembly of Sm2Co7/Co magnetic nanoparticles into highly stable and uniform nanospheres

Synthesis of Samarium-Cobalt Sub-micron Fibers and Their Excellent Hard Magnetic Properties

High-throughput synthesis of Samarium-Cobalt sub-micron fibers with controlled composition and dimension was demonstrated by combining electrospinning and reduction-diffusion processes. The composition of fibers was readily varied (8 < Sm < 20 at.%) by adjusting precursor composition whereas the diameter of fibers was precisely controlled by varying electrospinning parameters (e.g., applied voltage, solution feed rate, temperature, and humidity) to reach single-domain size. X-ray diffraction patterns confirmed that single phase Sm₂Co₁₇ fibers were synthesized when the metal precursor ratio (Sm³⁺/(Sm³⁺+Co²⁺)) was precisely controlled at 10.6%, whereas mixed phases (i.e., Co-Sm₂Co₁₇ or Sm₂Co₁₇-Sm₂Co₇) were observed when the ratio is deviated from the stoichiometric. Magnetic saturation (M_s ) of the synthesized fibers monotonically decreased with an increased in Sm content. In contrast, coercivity (H_ci) monotonically increased with an increase in Sm content.