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Preparation and characterization of SiO2 microspheres doped with CoFe2O4 nanocrystals

Tyrpekl V., Poltierová-Vejpravová J., Plocek J., Nižňanský D.

Materials Science Poland

2010

Vol. 28, No. 1

129--137

Main goal of the reported work was to fabricate silica microspheres doped with magnetic nanocrystals. Cobalt ferrite nanocrystals were fabricated separately via surfactant-assisted coprecipitation. The sol-gel method in microemulsion was subsequently used for encapsulating of the magnetic nanonanocrystals into the silica microspheres. Final products were characterized by various techniques and magnetic measurements. The obtained silica microspeheres doped with CoFe2O4 were of average diameter 11 žm.

Preparation of CuFe2O4/SiO2 nanocomposite by sol-gel method

Plocek J., Hutlová A., Nižňanský D., Buršik J., Rehspringer J.L., Mička Z.

Materials Science Poland

2005

Vol. 23, No. 3

697--705

This work has the aim to characterize the phase relations in the CuFe2O4/SiO2 system. The samples were prepared by the sol-gel method. Final heat treatment of the samples was carried out at temperatures in the range of 800-1100°C. Final products were characterized by HR TEM, X-ray diffraction, magnetic measurements, and Mössbauer spectroscopy. HR TEM revealed nanocrystals of the size of about 7-130 nm, depending on the heat treatment temperature. The spinel structure of CuFe2O4 in the amorphous silica matrix proved to be stable up to 1100°C without decomposition to the copper silicate and iron (III) oxide. At the same time, the amorphous silica matrix recrystallized to the cristobalite at 1100°C.