Enhancement of Interparticle Exchange Coupling in CoFe2O4/CoFe2 Composite Nanoceramics Via Spark Plasma Sintering Technology |
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| Authors: | Yue Zhang Zhi Yang Wei Yu Benpeng Zhu Shi Chen Xiaofei Yang |
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| Affiliation: | 1. School of Optical and Electronic Information, Huazhong University of Science and Technology, , Wuhan, 430074 China;2. Key Laboratory of Artificial Micro‐ and Nano‐structures of Ministry of Education and School of Physics and Technology, Wuhan University, , Wuhan, 430072 China;3. Department of Physics and Astronomy, University of Pittsburgh, , Pittsburgh, Pennsylvania, 15260 |
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| Abstract: | Powders and nanoceramics composed of composites of CoFe2O4, CoFe2, and a small amount of FeO were prepared by heating CoFe2O4 powder in reducing atmosphere and by sintering the product of reducing reaction at 350°C via spark plasma sintering technology. In the powders, increase in the molar ratios of CoFe2:CoFe2O4 and a great change in magnetic parameters were observed with the change in heating temperature from 300°C to 400°C, and the dominance of dipole interaction over exchange coupling in the interparticle interactions was confirmed by the steps in magnetic hysteresis loops and the negative Henkel plots. However, in the nanoceramics, significant enhancement in exchange coupling was found when the sintering temperature was raised to 500°C and 650°C, which was confirmed by both the positivity of Henkel plot and the single‐phase style of the magnetic hysteresis loop. |
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