A research group headed by Professor Hui Wang and Associate Professor Zhigao Sheng from the Chinese Academy of Sciences reported the synthesis of polyvinylpyrrolidone-directed nickel nanowires (PNNWs) via solvothermal technique supported by a strong magnetic field in work published in Advanced Materials Interfaces.
Schematic illustration of EW attenuation mechanisms of 9T-PNNW samples. a. EW incidence; b. interfacial polarization; c. magnetic loss; d. conductive loss, and dipolar polarization. Image Credit: HFIPS
One-dimensional magnetic nanowires have gained attention among the various microwave absorbers that have been explored because of their good mechanical qualities, large aspect ratio, and outstanding electrical transmission performance.
However, the smooth surface and negligible magnetism of nickel nanowires manufactured using standard methods prevent electromagnetic waves (EW) from passing through the absorber and dissipating heat energy. As a result, it is essential to devise a novel approach for increasing the surface roughness and magnetic characteristics of nickel nanowires, as well as improving their microwave absorption capability.
The scientists used a solvothermal approach generated by an external magnetic field to synthesize PNNWs in this research, and the morphology and characteristics of the PNNWs demonstrated a magnetic field strength-dependent relationship.
9T-PNNW fabricated in a 9 T (tesla) magnetic field has a greater aspect ratio, a more significant specific surface area, and improved magnetic characteristics, resulting in good microwave absorption performance. At 4.08 GHz, the minimum reflection loss (29.82 dB) is achieved with a thickness of 4.5 mm. The effective absorption bandwidth from 14.4 GHz to 18.0 GHz can surpass 3.6 GHz when the thickness is 1.5 mm.
According to scientists, this material generates a variety of electromagnetic loss mechanisms to attenuate electromagnetic waves, with dielectric loss dominating and magnetic loss, current loss, and resonance effect merely playing an auxiliary role.
This research sets the stage for the rational design and fabrication of nickel nanowires, and more crucially, the magnetic field has reference significance for the regulation of absorbent performance.
The research was funded by the National Key R&D Program of China, the National Natural Science Foundation of China, the Hefei Institutes of Physical Science Director’s Fund, etc.
Journal Reference:
Qian, Y., et al. (2022) Magnetic Field-Induced Synthesis of One-Dimensional Nickel Nanowires for Enhanced Microwave Absorption. Advanced Materials Interfaces. doi.org/10.1002/admi.202201604.