Solution synthesis and novel magnetic properties of ball-chain iron nanofibers

The current work describes the simple solution process of ball-chain polycrystalline Fe nanofibers with aspect ratios (lambda) and diameters (D) of over 1-65 and 30-95 nm. Static magnetic and microwave electromagnetic property studies demonstrated that such properties strongly depend on the lambda and D of the Fe nanofibers. As the lambda and D increase, the U-shape of the saturation magnetization (M-s) reaches a maximum of 180.0 emu.g (1), owing to the cooperative action of nanoeffects and magnetic interactions, whereas the coercivity (H-c) gradually increases due to aspect ratio variations. In contrast, the change in trends of the permittivity (epsilon', epsilon '') and the dielectric loss (tg delta(E)) are represented as an inverted U-shape; the permeability (mu', mu '') and magnetic loss (tg delta(M)) increase at low-frequency ranges and decrease at high frequency ranges. Stronger absorption and broader bandwidths of Fe nanofibers compared with Fe nanoparticles are ascribed to higher dielectric losses. The prepared Fe nanofibers have high potential in light-weight and broad bandwidth microwave absorbing applications.