DC CONDUCTIVITY OF TUNGSTEN-TELLURIDE PHOSPHATE-GLASSES

The dc conductivity of two samples of WO3-TeO2-P2O5 glasses in the temperature range 125-480 K was measured. Conductivity of these glasses is higher than those for lead-tungsten-phosphate glasses having comparable composition of tungsten ions. Small polaron theory has been used to establish the characteristic energies of the carriers. Value of the electron wave function decay constant, alpha, has been evaluated [assuming N(E(F)) = 10(20) (eV-1 cm-3)] to be 2.06 angstrom-1. Greaves's variable range hopping seems to be valid at intermediate temperatures [Greaves G N, J Non-Cryst Solids (Netherlands), 11 (1973) 427].