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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 28, Number 12
BKCSDE 28(12)
December 20, 2007

Title	Structure and Magnetic Characterization of Core-Shell Fe@ZrO₂ Nanoparticles Synthesized by Sol-Gel Process
Author	Girija S. Chaubey, Jinkwon Kim*
Keywords	Iron nanoparticles, Core-shell, Zirconium oxide, Coating, Magnetization
Abstract	Highly crystalline, uniform Fe nanoparticles were successfully synthesized and encapsulated in zirconia shell using sol-gel process. Two different approaches have been employed for the coating of Fe nanoparticle with zirconia. The thickness of zirconia shell can be readily controlled by altering molar ratio of Fe nanoparticle core to zirconia precursor in the first case where as reaction time was found to be most effective parameter to controlled the shell thickness in the second method. The structure and magnetic properties of the ZrO₂-coated Fe nanoparticles were studied. TEM and HRTEM images show a typical core/shell structure in which spherical α-iron crystal sized of ~25 nm is surrounded by amorphous ZrO₂ coating layer. TGA study showed an evidence of weight loss of less than 2% over the temperature range of 50-500 °C. The nanoparticles are basically in ferromagnetic state and their magnetic properties depend strongly on annealing temperature. The thermal treatment carried out in as-prepared sample resulted in reduction of coercivity and an increase in saturation magnetization. X-ray diffraction experiments on the samples after annealing at 400-600 °C indicate that the size of the Fe@ZrO₂ particles is increased slightly with increasing annealing temperature, indicating the ZrO₂ coating layer is effective to interrupt growing of iron particle according to heat treatment.
Page	2279 - 0
Full Text	PDF

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