Materials scientists have developed a rapid method for the production of epsilon iron oxide and have demonstrated that this raw material is promising for next-generation communication devices. Due to its excellent magnetic properties, it is one of the most sought after materials for the upcoming 6G generation of communication devices and for permanent magnetic recording. The work was published in the Journal of Materials Chemistry C.
Iron oxide (III) is one of the most common oxides on Earth. It is mostly found in the form of hematite (or alpha iron oxide, α-Fe2O3) mineral. Another stable and common modification is maghemite (or gamma modification, γ-Fe2O3). The former is widely used in industry as a red pigment and the latter as a magnetic medium. The two modifications differ not only in their crystal structure (alpha-iron oxide is characterized by hexagonal crystals and gamma-iron oxide by cubic crystals) but also in their magnetic properties.
In these forms of iron oxide (III) in addition, there are more exotic modifications, such as the epsilon, beta, zeta, and even the glassy versions. The most attractive for the high-tech industry is epsilon iron oxide, ε-Fe2O3. This variant has an extremely high coercive force (the ability of a material to resist an external magnetic field). The force reaches 20 kOe at room temperature, which is comparable to the parameters of magnets based on expensive rare earth elements. In addition, the material absorbs electromagnetic radiation in the subterahertz frequency range (100-300 GHz) under the influence of natural ferromagnetic resonance, the frequency of which is one of the criteria for the use of materials in wireless communication devices (4G standard megahertz and 5G tens of gigahertz). . It is planned that the sixth generation (6G) wireless technology, which is being actively introduced into our lives from the early 2030s, will use the sub-terahertz domain as the working domain, writes the Moscow Institute of Physics and Technology (MIPT) newsletter.
The resulting material is suitable for the manufacture of converter units or absorber circuits at these frequencies. Using composite ε-Fe2O3 nanopowders, for example, it will be possible to produce paints that absorb electromagnetic waves, thus shielding rooms from external signals and protecting signals from outside eavesdropping. Ε-Fe2O3 itself can be used in 6G receiving devices
Epsilon iron oxide is an extremely rare and difficult to extract form of iron oxide. Today it is produced in very small quantities and the process itself can take up to a month. This, of course, precludes its wide application. The authors of the study have developed a method for the accelerated synthesis of epsilon iron oxide that can reduce the synthesis time to one day (i.e., perform a full cycle more than 30 times faster!) And increase the amount of product formed. The technique is easy to reproduce, inexpensive and easy to apply in industry, and the materials needed for synthesis – iron and silicon – are among the most abundant elements on Earth.
“Although the epsilon iron oxide phase has been in use for a relatively long time, It was produced in pure form in 2004. Due to the complexity of the synthesis, it still has no industrial application, for example as a carrier for magnetic recording. We have significantly simplified the technology, “said Yevgeny Gorbachev, a researcher at Moscow State University’s Department of Materials Science.
“Materials with such a high ferromagnetic resonance frequency have huge potential for practical application. Today, terahertz technology is flourishing. These include the Internet of Things, ultrafast communication, science in the narrower sense. yos devices, and this is the next generation of medical technology. While last year’s popular 5G standard operates on tens of gigahertz, our materials pave the way for significantly higher (hundreds of gigahertz) frequencies, which means we’re already working on 6G and higher standards. Now it’s up to the engineers, we’re happy to share the information with them, and we can’t wait to hold a 6G phone in our hands, “said Dr. Lyudmila Aljabjeva, senior researcher at the MIPT Laboratory of Terahertz Spectroscopy, where the terahertz research was conducted.
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