Electrical conduction in composites of nanosized iron particles and oxide glasses

Nanocomposites involving iron particles in silica glass matrix have been synthesized by the hot pressing of suitably reduced precursor gel powders. The metal particles have diameters in the range 3.8 to 10.2 nm. An almost four orders of magnitude resistivity range at room temperature has been obtained by such changes in particle diameters. The resistivity in the temperature range 200–340 K shows a fractional temperature dependence with an average value of n ~ 0.69. The resistivity changes in this temperature region can be explained on the basis of an electron tunneling mechanism.