Moscow State University(MSU) and Moscow Institute of Physics and Technology (MIPT) materials scientists have developed a quick process for synthesizing epsilon-iron oxide, which has shown potential for application in next-generation communication devices. Its exceptional magnetic properties make it one of the most sought-after materials for next-generation 6G communication equipment and highly reliable magnetic recording systems, for example.
The inorganic compound iron(III) oxide, sometimes known as ferric oxide, has the formula Fe2O3. It’s one of the most common oxides on the planet. Iron(II) oxide (FeO), which is unusual, and iron(II, III) oxide (Fe3O4), which naturally occurs as the mineral magnetite, are the other two main oxides of iron. Maghemite (or gamma modification, ε-Fe2O3) is another stable and common modification. The former is commonly utilized as a red pigment in industry, while the latter is being used as a magnetic recording medium.
Fe2O3 is the principal source of iron for the steel industry as the mineral hematite. Iron(III) oxide has the chemical formula Fe2O3, which has three oxygen atoms and two iron atoms. Fe2O3 has a +3 oxidation state. The difference in electronegativity between oxygen and iron determines the development of bonds between these two atoms. While iron(Fe) is a metal, oxygen(O2) is a non-metal. As a result, such bonds are referred to as ionic bonds.
Acids have an easy time attacking Fe2O3. Rust is a common name for iron(III) oxide, and it is accurate to some extent because the two have similar properties and compositions. However, in chemistry, rust is classified as an ill-defined material known as Hydrous ferric oxide. The material (-Fe2O3) has exceptional magnetic properties, making it one of the most sought-after materials for communication devices and long-term magnetic storage.
There are more complex variations of iron oxide (III) than these, such as epsilon-, beta-, zeta-, and even glassy. Epsilon iron oxide, ε- Fe2O3, is the most appealing phase. This modification exerts a tremendous amount of coercion (the ability of the material to resist an external magnetic field). At room temperature, the strength reaches 20 kOe, which is similar to the magnet parameters based on costly rare-earth elements.
Furthermore, due to the effect of natural ferromagnetic resonance, the material absorbs electromagnetic radiation in the sub-terahertz frequency range (100-300 GHz). One of the conditions for using materials in wireless communications devices is the frequency of such resonance—the 4G standard utilizes megahertz, whereas 5G employs tens of gigahertz. The sixth-generation (6G) wireless technology, which is being readied for active adoption in our lives from the early 2030s, is expected to employ the sub-terahertz range as a working range.
At these frequencies, the resultant material can be used to make conversion units or absorber circuits. For instance, utilizing composite ε- Fe2O3nanopowders, paints that absorb electromagnetic waves will be able to shield rooms from unwanted signals, and safeguard signals from outside interception will be possible. The ε- Fe2O3 can also be employed in 6G reception devices on its own.
This, of course, prohibits its widespread application. The study’s authors devised an accelerated synthesis method for epsilon iron oxide that reduced the synthesis time to just a day (that is, to finish a full cycle more than 30 times faster!) while also increasing the quantity of the finished product. The method is straightforward to replicate, inexpensive, and easy to deploy in industry, and the materials needed for synthesis—iron and silicon—are among the most abundant elements on the planet.
Russian scientists have devised a way for completing a day’s worth of synthesis in a single day with a higher yield of the resulting product. Evgeny Gorbachev, a Ph.D. student at Moscow State University’s Department of Materials Sciences and the study’s lead author explained that even though the epsilon-iron oxide phase was achieved in pure form only a few years ago, it has yet to find practical application due to the difficulty of its production, such as as a medium for magnetic recording. According to him, they were able to significantly simplify the technique.
Research into the fundamental physical properties of materials with record-breaking properties is crucial to their effective use. Without a thorough examination, the material may be disregarded for many years, as has occurred before in the history of science. The success of the development was due to the collaboration of materials scientists from Moscow State University who synthesized the compound and physicists from MIPT who researched it in depth.
The potential for useful uses of materials with such high ferromagnetic resonance frequencies is immense. Senior Researcher, Laboratory of Terahertz Spectroscopy, MIPT, Dr. Liudmila Alyabyeva, Ph.D. explained that Terahertz technology is blooming today: it’s the ultra-fast communications, Internet of Things, scientific gadgets with a narrower focus, and next-generation medical technology.
Dr. Alyabyeva added that while the 5G standard, which was very successful last year, regulates at frequencies in the tens of gigahertz, their materials are giving way to very high frequencies (hundreds of gigahertz), which implies that they are already dealing with 6G standards and even higher. According to him, it’s up to the engineers; as they are pleased to share the information with them and can’t wait to get their hands on a 6G phone.
Gorbachev, E., et al. (2021) Tuning the particle size, natural ferromagnetic resonance frequency, and magnetic properties of ε- Fe2O3 nanoparticles prepared by a rapid sol–gel method. Journal of Materials Chemistry C. doi.org/10.1039/D1TC01242H.