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  • 1 National Institute of Bioscience and Human-Technology 1-1 Higashi 305 Tsukuba, Ibaraki Japan
  • 2 National Institute of Materials and Chemical Research 1-1 Higashi 305 Tsukuba, Ibaraki Japan
  • 3 Kubota Corporation Advanced Technology Laboratory 5-6 Koyodai 301 Ryugasaki, Ibaraki Japan
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Spinel iron oxide (Fe3O4-γ-Fe2O3) particles were supported on microbeads of silica gel by the calcination of the silica gel base adsorbing citric acid and Fe3+ ions. The X-ray diffraction patterns and the57Fe Mössbauer spectra measured for the spinel iron oxide indicated that the particle size of the oxide was regulated by the mean pore diameter (4–82 nm) of the silica gel support employed. In the case of α-Fe2O3 particles prepared by using the same silica gel beads, it was revealed by the Mössbauer spectra and the electron micrographs that there were relatively large particles of the oxide on the surface of the beads, in addition to the particles in the silica gel micropores.