MMM 2022

November 07, 2022

Minneapolis, United States

The Role of Stoichiometry in Mn1 xZnx Ferrite Microwave Absorbers

As 5G technology moves higher into the microwave frequency regime, the risk of coupling EM energy into susceptible electronic circuits grows. Minimizing this interference is driving the need for compact, lightweight broadband absorbers to protect sensitive and high precision electronics. Manganese zinc ferrite (Mn1-xZnxFe2O4) microparticles have previously been demonstrated to be magnetically lossy up to 10 GHz, the desired frequency regime, and have the potential to meet the energy density and attenuation performance needs 1, 2. However, optimizing the shielding effectiveness requires improved understanding of Mn1-xZnx stoichiometry and the dominant dielectric and magnetic absorption mechanisms for each stoichiometry. This presentation discusses results, up to 20 GHz, from experimentally investigating the shielding effectiveness and quality factor attenuation of Mn1-xZnxFe2O4 with a mean particle size of 30 microns, loaded to 50 volume percent in epoxy, and variation in x values from 0 to 1 in intervals of 0.1. Complex permeability and permittivity measurements were conducted to identify the absorption mechanism. An increase in absorption was observed in Mn1-xZnxFe2O4 for x=0.3 and 0.4 compared with other stoichiometries. A likely explanation of the observed increase is provided 3.
1 T. Tsutaoka, Journal of Applied Physics 93, 2789 (2003);
2 R. Dosoudil, M. Usakova, J. Franek, J. Slama and A. Gruskova, "Particle Size and Concentration Effect on Permeability and EM-Wave Absorption Properties of Hybrid Ferrite Polymer Composites," in IEEE Transactions on Magnetics, vol. 46, no. 2, pp. 436-439, Feb. 2010, doi: 10.1109/TMAG.2009.2033347.
3 This work was supported by the Laboratory Directed Research and Development program at Sandia National Laboratories, a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia LLC, a wholly owned subsidiary of Honeywell International Inc. for the U.S. Department of Energy?s National Nuclear Security Administration under contract DE-NA0003525.

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