1993 Volume 101 Issue 1180 Pages 1351-1357
Glasses in the system of V2O5-ZnO-TeO2 glasses were prepared by rapid quenching and their dc-condutivity was studied. A large glass formation region was found i.e., ZnO=0-60mol%, V2O5=0-70mol%, TeO2=30-100mol%. The glasses were found to be n-type semiconductors. Dc-conductivities (σ) were in the range from 9.5×10-7 to 5.7×10-7S⋅cm-1 at 473K for V2O5=30-60mol%. The conduction was due to adiabatic small polaron hopping and non-adiabatic small polaron hopping for the glasses with V2O5>50 and V2O5<50mol%, respectively. The polaron band width (J) was estimated to be 0.01-0.10eV. The evaluated carrier mobilities μ were in the range from 4.1×10-8 to 8.9×10-7cm2⋅V-1⋅s-1 at 473K. The values of J and μ satisfied the conditions for the small polaron hopping conduction. The estimated carrier density (NC) was 0.15×1021-2.89×1021cm-3, depending upon V2O5 concentration. Seebeck coefficients (Q) of the glasses determined in the temperature range of 100-200°C exhibited no temperature dependence, and thus it is concluded that the dominant factor responsible for Q was the amount of V4+.
