The rapid development of the electronics industry has sparked widespread interest in transparent microwave-absorbing materials, due to their applications in EMI shielding windows and domes in aircraft and vessels, as well as panels and surveillance cameras for optical detection devices and aerospace exploration facilities.
Current transparent microwave-absorbing materials usually construct ultra-thin conductive structures on ordinary optical glass substrates to both achieve microwave-absorbing performance and optical transmittance in the visible and near-infrared ranges. These optical glass substrates, characterized by their insulating properties and microwave-transmitting attributes, offer optical transparency and serve as the foundation for microwave absorbers. This condition constrains the prospects of enhancing the comprehensive efficacy of transparent microwave-absorbing materials. Therefore, exploring novel substrates that achieve both high optical transparency and microwave absorption for advancements in this critical field is of considerable significance.
A research team led by Prof. WANG Pengfei from the Xi'an Institute of Optics and Precision Mechanics of the Chinese Academy of Sciences has synthesized AgI-AgPO3-WO3 transparent conductive glasses and comprehensively investigated their structures, optical and electrical properties, microwave absorption performance, and radar cross section reduction. This study was published in Chemical Engineering Journal on Feb.15.
The results showed that the increase in the AgI content in the glasses caused fragmentation of the Q2-related phosphate chains and augmentation of non-bridging oxygen bonds, resulting in reduced tightness of the glass network structure. Consequently, the introduction of AgI significantly enhanced the electrical properties, electromagnetic parameters, and microwave absorption performance of the glasses, albeit at the expense of the optical transmittance and thermal stability.
The 45AgI-45AgPO3-10WO3 sample exhibited satisfactory microwave absorption, achieving a minimum reflection loss (RLmin) of -47.18 dB, effective absorption bandwidth (EAB) of 1.97 GHz, and RCS reduction of 31.46 dB m2 in the X band. This was attributed to the synergistic effects of dielectric and magnetic losses, and impedance matching and electromagnetic attenuation. This sample also exhibited an optical transmittance of ~80% in the range of 500-2000 nm.
This study highlights the potential use of transparent conductive glasses as transparent microwave-absorbing media for electromagnetic interference shielding applications in optical windows and domes, and stealth applications in high-performance optical cameras and optical detection device systems.
( Date of Publication: Feb.15 2024 )
Schematic illustration of the possible microwave absorption mechanisms of the AAW glasses.(Image by XIOPM)
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