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Electrical properties of Fe-Fe 3O 4-SiO 2 gel nanocomposites
Published in -
PMID: 15570971
Volume: 4
Issue: 7
Pages: 849 - 854
Nanocomposites containing Fe 3O 4 and α-Fe, respectively, in a SiO 2 gel were prepared by subjecting a suitably chosen gel with iron ions to a reduction treatment at 923 K, followed by wet oxidation at the same temperature for 1 hour. The particle sizes of the two phases were estimated to have values in the range of 18 to 25 nm. The dc conductivity of the composites was found to arise due to a variable range hopping mechanism with a density of states calculated as ∼10 18 eV -1 cc -1. The nanoparticles of α-Fe are believed to contribute to the latter. The ac conductivity variation as a function of frequency and temperature could be explained because of an overlapping small polaron tunneling mechanism in the Fe 3O 4 nanoparticles. The density of states estimated in the latter case was ∼10 18 eV -1 cc -1. From the dielectric modulus spectra of the nanocomposites, a Kohlrausch-Williams-Watts (KWW) exponent of ∼0.30 was extracted. This indicated the presence of a wide distribution of relaxation times in the system.
About the journal
JournalJournal of Nanoscience and Nanotechnology
Open AccessNo