What is it about?
Soft magnetic materials are used in transformers, electric motors, inductors and many other devices that control or convert electrical energy. In this study, iron powder particles were coated with a small amount of magnesium oxide and then heated using microwaves. This faster heating method changed the thin layer between the particles and improved several important magnetic properties. The results show that the amount of magnesium oxide can be adjusted depending on the intended application. Lower amounts support higher magnetic permeability and lower losses under direct-current conditions, while a higher amount improves electrical insulation, reduces high-frequency losses and provides better stability under a direct magnetic bias. Compared with conventional furnace heating, microwave treatment achieved improved performance in a much shorter processing time and with lower estimated energy consumption. The findings may help researchers and manufacturers design more efficient magnetic components for compact, energy-efficient electrical devices.
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Why is it important?
This work is timely because modern electrical devices increasingly require magnetic components that are smaller, more efficient and capable of operating at higher frequencies. At the same time, manufacturers need processing methods that reduce energy use, production time and environmental impact. The study is distinctive because it directly links microwave heat treatment with the formation of a new iron–magnesium–oxygen interphase and shows how this interphase changes magnetic, electrical and mechanical performance. Unlike conventional furnace treatment, microwave processing produced improved permeability, lower losses and better DC-bias stability within a much shorter thermal cycle. These findings may help researchers and manufacturers select the appropriate magnesium oxide content and processing route for different applications. The results provide a practical basis for developing more efficient inductors, transformers and other magnetic components used in power electronics, electric mobility and energy-conversion systems.
Perspectives
From my perspective, the most interesting outcome of this work is that microwave heat treatment does more than simply shorten the processing time. It actively influences the formation of the thin interphase between the iron particles and the magnesium oxide insulation, and this interphase plays a decisive role in the final magnetic behaviour. I consider this particularly important because soft magnetic composites are often optimised mainly by changing composition or compaction conditions. Our results show that the heating route itself can be used as an additional design tool. By adjusting the MgO content and microwave treatment, it is possible to favour different combinations of permeability, electrical resistivity, magnetic losses and DC-bias stability. I believe that the next important step is to investigate how this interphase develops under different microwave conditions and whether the same approach can be transferred to other insulating systems. This could contribute to more energy-efficient processing and to magnetic components tailored more precisely for specific operating frequencies and applications.
Radovan Bures
Institute of Materials research of Slovak Academy of Sciences
Read the Original
This page is a summary of: Preparation and comprehensive characterisation of microwave heat treated soft magnetic Fe@MgO composites, Materials & Design, June 2026, Elsevier,
DOI: 10.1016/j.matdes.2026.116062.
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