Title: Electromagnetic Interference Shielding Response of Biphasic Lithium Iron Oxides

Speaker: Dr. Tapati Sarkar and Sagnik Ghosh — Department of Materials Science and Engineering; Solide State Physics, Uppsala University, Sweden

Where: Zoom (Meeting ID: 617 3126 3754, Passcode: 490241)

Abstract:

The widespread use of wireless communication devices has raised serious concerns about electromagnetic interference (EMI) pollution. Commonly used electronic devices (laptops, smartphones, radio, Wi-Fi, etc.) use the microwave frequency range (~GHz) to transfer data and communicate with each other. Hence, these devices are susceptible to interference from microwave signals emitted by other devices. This type of interference leads to noise, data corruption, data packet loss, and device malfunction. EMI pollution can cause severe damage to critical equipment in healthcare and aviation security.[1,2] Exposure to electromagnetic radiation can also be detrimental to wildlife.[3] Research on EMI shielding materials is crucial in order to combat these challenges posed by electromagnetic pollution. The main task of a good shielding material is to block (either by reflection or absorption) the unwanted microwave signals from reaching the victim device. The performance of a shielding material is measured by the amount of incident power that it is able to block from reaching the victim.

In this context, nanocomposites with dielectric and magnetic phases have been used to develop novel EMI shielding materials. Nanocomposites are advantageous since the morphology and interface formation between different phases can be controlled by carefully tuning the synthesis parameters. Moreover, nanocomposites with dielectric and magnetic properties can be paired together to develop biphasic composites that can harness the advantages of magneto-dielectric synergy leading to high absorption of microwaves.[4]

In this talk, the basics of EMI shielding mechanism will be discussed with special focus on the measurement setup. The EMI shielding performance of biphasic lithium iron oxides (ferrimagnetic α-LiFe₅O₈ and paramagnetic α-LiFeO₂) will be discussed based on the magnetic and dielectric properties of the two phases as well as the formation of interfaces.[2] The advantages and possibility of developing multiphasic composites with ferrite and 2-dimensional materials like WS₂ will also be explored.

References

[1] Mathur, P., Raman, S. Electromagnetic Interference (EMI): Measurement and Reduction Techniques. J. Electron. Mater. 49, 2975–2998 (2020). https://doi.org/10.1007/s11664-020-07979-1

[2] Ghosh, S., Rangaiah, P., Aboulsaad, M., Slimani, S., Cedervall, J., Aslibeiki, B., Augustine, R., Edvinsson, T., Barucca, G., Peddis, D., Sarkar, T. Biphasic Lithium Iron Oxide Nanocomposites for Enhancement in Electromagnetic Interference Shielding Properties. Journal of Alloys and Compounds. 1010, 177017 (2025). https://doi.org/10.1016/j.jallcom.2024.177017

[3] Balmori, A. Electromagnetic Pollution from Phone Masts. Effects on wildlife. Pathophysiology. 16, 191–199 (2009). https://doi.org/10.1016/j.pathophys.2009.01.007

[4] Mohapatra, P. P., Dobbidi, P. Effect of Carbon Reinforcement on the EMI Shielding Response of LiFe₅O₈ Ceramics, Materials Characterization. 189, 111985 (2022). https://doi.org/10.1016/j.matchar.2022.111985