Field-Assisted Synthesis and Electromagnetic Properties of Aligned Magnetic Nanostructures by γ-Irradiation Induced Reduction

We here demonstrate the preparation of magnetic nanostructures (Co, Ni) with aligned morphologies through a magnetic field-assisted gamma-irradiation route. It is found out that a proper magnetic field can induce the prepared magnetic nanoparticles to align into well-defined stick or chain structures, where randomly dispersed nanoparticles are obtained without the application of magnetic field. The alignment of the magnetic nanoparticles gives rise to increased magnetization and coercivity due to the enhancement in shape anisotropy. Meanwhile, compared with the scattered nanoparticles, stronger electromagnetic wave absorption properties can also be realized in the aligned nanostructures, caused by the geometrical effect. We think this alignment of magnetic nanoparticles into specific structures under the assistance of magnetic field may be appealing in improving the electromagnetic wave absorptions that are not accessible in randomly dispersed particles.