Search

Well-defined Co[Fe.sub.2][O.sub.4] nanoparticles embedded in an amorphous Si[O.sub.2] matrix have been synthesized by a sol-gel method, characterized and investigated by Mossbauer spectroscopy and magnetic properties measurements. The mean particle size increases from 3 to 15 nm consistently with the temperature of the subsequent annealing, which varied from 800[degrees]C to 1100[degrees]C, respectively. The composites exhibit superparamagnetic behavior with the blocking temperature [T.sub.B] increasing with the mean particle size from 80 to 350 K, respectively. Sufficiently high value of [H.sub.c] ~ 2.5 T (at 2 K) has been observed for the sample annealed at 1100[degrees]C. Index Terms--Ferrite nanoparticles, sol-gel method, superparamagnetism.

Well-defined CoFe2 O4 nanoparticles embedded in an amorphous SiO2 matrix have been synthesized by a sol-gel method, characterized and investigated by Mössbauer spectroscopy and magnetic properties measurements. The mean particle size increases from 3 to 15 nm consistently with the temperature of the subsequent annealing, which varied from 800°C to 1100°C, respectively. The composites exhibit superparamagnetic behavior with the blocking temperature TB increasing with the mean particle size from 80 to 350 K, respectively. Sufficiently high value of Hc ∼ 2.5 T (at 2 K) has been observed for the sample annealed at 1100°C. [ABSTRACT FROM AUTHOR]