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Synthesis, magnetic and optical properties of core/shell Co1-xZnxFe2O4/SiO2 nanoparticles.

Girgis E, Wahsh MM, Othman AG, Bandhu L, Rao K - Nanoscale Res Lett (2011)

Bottom Line: 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.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.

View Article: PubMed Central - HTML - PubMed

Affiliation: Solid State Physics Department, National Research Centre, 12311 Dokki, Giza, Egypt. egirgis@gmail.com.

ABSTRACT
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.

No MeSH data available.


Hysteresis loops of ZnFe2O4 nanoparticles uncoated (a) and coated with silica shell (b).
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Figure 5: Hysteresis loops of ZnFe2O4 nanoparticles uncoated (a) and coated with silica shell (b).

Mentions: Figure 5a shows the hysteresis loops of uncoated zinc ferrite samples fired at 400°C, 600°C, and 800°C. It is clear that the zinc ferrite nanoparticles fired at 400°C show a ferromagnetic behavior while by increasing the firing temperature to 600°C, the magnetization state of the zinc ferrite nanoparticles starts to transfer from the ferromagnetic state to the paramagnetic state. With the increase of the firing temperature up to 800°C the hysteresis loop of the zinc ferrite nanoparticles shows a typical paramagnetic behavior.


Synthesis, magnetic and optical properties of core/shell Co1-xZnxFe2O4/SiO2 nanoparticles.

Girgis E, Wahsh MM, Othman AG, Bandhu L, Rao K - Nanoscale Res Lett (2011)

Hysteresis loops of ZnFe2O4 nanoparticles uncoated (a) and coated with silica shell (b).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211881&req=5

Figure 5: Hysteresis loops of ZnFe2O4 nanoparticles uncoated (a) and coated with silica shell (b).
Mentions: Figure 5a shows the hysteresis loops of uncoated zinc ferrite samples fired at 400°C, 600°C, and 800°C. It is clear that the zinc ferrite nanoparticles fired at 400°C show a ferromagnetic behavior while by increasing the firing temperature to 600°C, the magnetization state of the zinc ferrite nanoparticles starts to transfer from the ferromagnetic state to the paramagnetic state. With the increase of the firing temperature up to 800°C the hysteresis loop of the zinc ferrite nanoparticles shows a typical paramagnetic behavior.

Bottom Line: 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.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.

View Article: PubMed Central - HTML - PubMed

Affiliation: Solid State Physics Department, National Research Centre, 12311 Dokki, Giza, Egypt. egirgis@gmail.com.

ABSTRACT
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.

No MeSH data available.