The 24th Yamazaki-Teiichi Prize Winner
Material
Development and Applications of Epsilon Iron Oxide Magnets
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Shin-ichi Ohkoshi Professor, Department of Chemistry, School of Science, The University of Tokyo |
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Asuka Namai Associate Professor, Department of Chemistry, School of Science, The University of Tokyo |
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Marie Yoshikiyo Assistant Professor, Department of Chemistry, School of Science, The University of Tokyo |
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Reason for award
Dr. Ohkoshi and his team successfully synthesized ε-Fe₂O₃ (ε-iron oxide), a new type of magnetic ferrite, as single-phase nanoparticles for the first time in the world in 2004 using a novel synthesis method, and demonstrated that it is a thermally stable magnetic material with high coercivity. This material possesses coercivity exceeding three times that of conventional hard magnetic ferrites and rivaling that of rare earth magnets. Moreover, by substituting various metals (such as Rh), Dr. Ohkoshi and his team were able to further enhance the coercivity value, achieving a record of 35 kOe at room temperature in 2017. They demonstrated that it is possible to achieve miniaturization while maintaining magnetic order, experimentally obtaining ε-Fe₂O₃ particles as small as 7.5 nm and discovering that they are the world's smallest hard ferrite magnets . They showed that epsilon iron oxide can absorb high-frequency millimeter waves (30–300 GHz) and that its resonance frequency can be controlled within the range of 35–240 GHz through metal substitution. Through industry-academia collaboration, numerous developments, such as millimeter-wave noise countermeasure components tailored to the needs of device manufacturers, are being promoted, promising a broad range of applications.
Dr. Ohkoshi and his team have actively disseminated this technology through academic papers, international conferences, and exhibitions, and their academic and social contributions are considered to be remarkable.
In recognition of the above achievements, Dr. Ohkoshi, Dr. Namai, and Dr. Yoshikiyo are awarded the 24th Yamazaki-Teiichi Prize in the field of Material.