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|Title:||Nanocrystalline maghemite (γ-Fe 2O 3) in silica by mechanical activation of precursors|
|Authors:||Xue, J. |
|Source:||Xue, J.,Zhou, Z.,Wang, J. (2002-04). Nanocrystalline maghemite (γ-Fe 2O 3) in silica by mechanical activation of precursors. Journal of the American Ceramic Society 85 (4) : 807-811. ScholarBank@NUS Repository.|
|Abstract:||γ-Fe 2O 3 nanocrystallites dispersed in an amorphous silica matrix have been successfully prepared for the first time by mechanical activation of a chemistry-derived precursor at room temperature. The initial 10 h of mechanical activation triggered the formation of nanocrystallites of Fe 3O 4 in a highly activated matrix. Increasing the mechanical-activation time led to a phase transformation from Fe 3O 4 to γ-Fe 2O 3. The γ-Fe 2O 3 phase was well established after mechanical activation of the precursor for 30 h. Further increasing the mechanical-activation time to 40 h induced the formation of α-Fe 2O 3. The mechanical-activation-grown γ-Fe 2O 3 nanocrystallites were ∼10-12 nm in size and well dispersed in the silica matrix, as observed using TEM. They demonstrated super-paramagnetic behavior at room temperature when measured using a Mössbauer spectrometer and a vibrating sample magnetometer (VSM). In addition, the γ-Fe 2O 3 derived from 30 h of mechanical activation exhibited a value of saturation magnetization as high as 62.6 emu/g.|
|Source Title:||Journal of the American Ceramic Society|
|Appears in Collections:||Staff Publications|
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