A research team led by Prof. SHENG Zhigao at the High Magnetic Field Laboratory, Hefei Institutes of Physical Science, Chinese Academy of Sciences, has successfully manipulated the structure and microwave absorption of CoxSe nanosheets by synthesizing them under a high magnetic field (HMF). The material' s reflection loss improved dramatically from −6.3 dB at 0 T to −66.3 dB at 10 T in the C-band (4–8 GHz), representing more than a tenfold improvement.
The findings were recently published in Chemical Engineering Journal.
Microwave-absorbing materials are essential for reducing electromagnetic interference in radar and wireless communication systems. As electronic devices continuously emit electromagnetic waves, effective absorption in the C-band frequency range is increasingly important for improving signal stability and minimizing interference.
The team presented a systematic investigation into the magneto-synthetic control of heterophase CoxSe nanosheets under HMF using a magneto-solvothermal setup, which consists of a superconducting magnet, a heating reactor, and a water chiller. This setup allowed the material to form under precisely controlled HMF, adding a new level of control beyond traditional synthesis parameters such as temperature and pressure.
Under the HMF, the composition of CoxSe was modulated to form heterophase Co0.85Se/Co0.5Se nanosheets with anisotropic growth. At the same time, the material underwent a magnetic transition from paramagnetic to ferromagnetic behavior, showing that the magnetic field not only influenced its structure but also fundamentally altered its magnetic properties.
The study shows that HMF can act as an effective tuning tool in materials synthesis. By introducing this extreme condition, researchers are able to control both structure and performance at the same time, and even obtain material phases that are difficult to achieve under conventional conditions.
"This magneto-synthesis approach offers a novel strategy for manipulating materials growth and designing advanced functional materials in broad applications," explained Dr. Khalifa, a member of the team.
Synthesis of heterophase CoxSe nanosheets under high magnetic field: Modulation of composition, morphology, magnetism, and microwave absorption (Image by Khalifa)
