Mohan Kant, K and Sethupathi, K. and Ramachandra Rao, M. S. (2008) Tuning the magnetization dynamics of silica-coated Fe3O4 core-shell nanoparticles by shell thickness control. Journal of Applied Physics, , 103 (7). 07D501.
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Core-shell silica (SiO2)-coated Fe3O4 nanoparticles of shell thickness between 2 and 52 nm have been synthesized and characterized. The saturation magnetization scales with SiO2 wt % and these samples exhibit negligible hysteresis at room temperature, as compared to the bulk Fe3O4. The peak in the temperature-dependent ac susceptibility Tm shifts toward higher temperature with increasing frequency. Data of pristine to 40 wt % SiO2-coated samples fit to critical slowing-down behavior model yielding relaxation time of ~10-10 s. For particles of higher shell thickness, smaller relaxation time of ~10-13 s is obtained. Temperature-dependent electron spin resonance measurements suggest overall weakening of magnetic interactions in Fe3O4 nanoparticles of thicker SiO2 shell. Variation of shell thickness in these core-shell nanoparticles could lead to diverse ground states ranging from interacting to noninteracting systems.
|Subjects:||Physical Science > Nanophysics|
Physical Science > Nano objects
Material Science > Nanochemistry
Material Science > Nanostructured materials
|Divisions:||Faculty of Engineering, Science and Mathematics > School of Physics|
Faculty of Engineering, Science and Mathematics > School of Chemistry
|Deposited On:||11 Aug 2009 07:20|
|Last Modified:||11 Aug 2009 07:20|
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