Connectivity concept

Researchers produce material capable of absorbing 6G frequencies

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Scientists at the Korea Institute of Materials Science (KIMS) have manufactured one of the few magnetic materials that can absorb ultra-high frequencies that could be leveraged by 6G technologies.

The technology is considered the developed the world’s first continuous manufacturing technology for millimetre wave-absorbing magnetic materials. 

The material in question is epsilon iron oxide, known for its ability to absorb millimetre waves with a coercive force equivalent to that of neodymium (Nd) magnets. Epsilon iron oxide is also almost the only magnetic material that absorbs ultra-high frequencies (30 to 200GHz), which is a potential 6G frequency band.

Until recently, this material could only be formed in particles of under 50 nanometres. A team in Japan did manage to produce pure epsilon iron oxide, but their technique is not considered practical, as it involves a time-consuming multi-stage process. 

In contrast, the researchers at KIMS have been able to continuously manufacture epsilon iron oxide through a process that would facilitate the commercialisation of the material.  

“The significance of the study is that it developed the first continuous manufacturing process of epsilon iron oxides," said Dr. Youn-kyoung Baek, one of the leaders of the investigation. 

"The technology is expected to accelerate the commercialisation of wireless communication devices using millimetre waves, self-driving car radars, and absorber technology for space satellite communication in the future.”

To achieve this, the team produced a composite powder in which epsilon iron oxide nanoparticles are embedded in silica particles by spray-drying precursor solutions in a hot chamber.

When the precursor material solution is continuously injected and the droplets are instantly dried, the iron precursor is trapped in the silica xerogel particles and grow during heat treatment. 

Materials that are able to absorb high frequencies are fundamental for the development of future communication technologies, as the majority of conventional metals used today have reduced absorption capacity in high-frequency bands. 

Therefore, epsilon iron oxide could be a key component in the commercialisation of solutions including mm-wave 5G/6G wireless communication, radar sensors for driverless car, and stealth and low-orbit satellite communication components.

In addition, as it is a high-coercivity magnetic material, epsilon iron oxide could be used for electric motor parts for future mobility.

At the moment, no companies commercially produce products with applied magnetic materials capable of absorbing mm waves. Only two or three companies in the US, Japan, and Germany produce 5G-band absorbing and shielding materials. 

The KIMS  team is currently discussing technology transfer for mass production of iron oxide absorbing materials with several companies and is conducting a follow-up study to improve wave absorption capacity to terahertz. 

The research done by the KIMS team was published in the journal Chemical Communications

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