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Alternating current conductivity of the interfacial phase in copper oxide–silica gel nanocomposites

Published online by Cambridge University Press:  31 January 2011

D. Das  and
D. Chakravorty
D. Das
Affiliation:
Indian Association for the Cultivation of Science, Calcutta, 700 032, India
D. Chakravorty
Affiliation:
Indian Association for the Cultivation of Science, Calcutta, 700 032, India
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Abstract

A nanocomposite structure was induced in gel of composition 60CuO · 40SiO2 (mol%) by first of all precipitating nano-sized copper particles by a reduction treatment and subsequently subjecting these to a controlled oxidation treatment. The particle size was of the order of 6.8 nm. Alternating current (ac) conductivity measurements were carried out on different specimens in the temperature range 300 to 630 K covering a frequency spectrum 0.1 kHz to 2 MHz. The ac conductivity was found to have a variation with frequency given by ωs, ω being the angular frequency and s the frequency exponent. The analysis of the variation of s as a function of temperature led to the conclusion that an overlapping large polaron tunneling mechanism was operative in this system. The effective barrier height for polaron transfer for infinite intersite separation was found to be almost twice in the case of the precursor gel as compared to that for the composite with the interfacial amorphous phase.

Type
Articles
Information
Journal of Materials Research , Volume 16 , Issue 4 , April 2001 , pp. 1047 - 1051
Copyright
Copyright © Materials Research Society 2001

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