DC electrical conduction in tungsten phosphate glasses

Abstract The dc conductivity of semiconducting tungsten phosphate glasses of three different compositions has been measured over a temperature range 100–400 K. The data have been analysed in the light of existing models of polaronic hopping conduction. The high-temperature region can be qualitatively explained by small-polaron hopping between nearest neighbours, while at low temperatures (below 150 K), the behaviour can be explained by Mott's variable-range hopping. The value of the electron decay constant α estimated from variable-range hopping is of the order of 2 A −1 , but the estimated disorder energy W D is twice as large as the measured low-temperature activation energy.