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Synthesis, magnetic and optical properties of core/shell Co1-x Zn x Fe2O4/SiO2 nanoparticles

Emad Girgis14*, Mohamed MS Wahsh2, Atef GM Othman2, Lokeshwar Bandhu3 and KV Rao3

Author Affiliations

1 Solid State Physics Department, National Research Centre, 12311 Dokki, Giza, Egypt

2 Refractories, Ceramics and Building Materials Department, National Research Centre, 12311 Dokki, Giza, Egypt

3 Department of Materials Science, Royal Institute of Technology, Stockholm, 100 44 Sweden

4 Advanced Materials and Nanotechnology Lab, CEAS, National Research Centre (NRC), El-Behouth Street, 12311 Dokki, Giza, Egypt

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Nanoscale Research Letters 2011, 6:460  doi:10.1186/1556-276X-6-460

Published: 20 July 2011


The optical properties of multi-functionalized cobalt ferrite (CoFe2O4), cobalt zinc ferrite (Co0.5Zn0.5Fe2O4), and zinc ferrite (ZnFe2O4) nanoparticles have been enhanced by coating them with silica shell using a modified Stöber method. The ferrites nanoparticles were prepared by a modified citrate gel technique. These core/shell ferrites nanoparticles have been fired at temperatures: 400°C, 600°C and 800°C, respectively, for 2 h. The composition, phase, and morphology of the prepared core/shell ferrites nanoparticles were determined by X-ray diffraction and transmission electron microscopy, respectively. The diffuse reflectance and magnetic properties of the core/shell ferrites nanoparticles at room temperature were investigated using UV/VIS double-beam spectrophotometer and vibrating sample magnetometer, respectively. It was found that, by increasing the firing temperature from 400°C to 800°C, the average crystallite size of the core/shell ferrites nanoparticles increases. The cobalt ferrite nanoparticles fired at temperature 800°C; show the highest saturation magnetization while the zinc ferrite nanoparticles coated with silica shell shows the highest diffuse reflectance. On the other hand, core/shell zinc ferrite/silica nanoparticles fired at 400°C show a ferromagnetic behavior and high diffuse reflectance when compared with all the uncoated or coated ferrites nanoparticles. These characteristics of core/shell zinc ferrite/silica nanostructures make them promising candidates for magneto-optical nanodevice applications.

nanostructures; oxides; cobalt ferrite; cobalt zinc ferrite; zinc ferrite; magnetic properties; diffuse reflectance.