Electrical conductivity of V₂O₅-SnO-TeO₂ glasses

Abstract

Electrical conductivity of glasses in the system V₂O₅-SnO-TeO₂ prepared by press quenching is measured and the mechanism of conduction related to glass composition is discussed. The glass forming region was found in the composition range (in mol%): 0 to 70 V₂O₅, 0 to 30 SnO and 30 to 100 TeO₂. Dc conductivities ranged from 2.1 * 10⁻⁵ to 5.4- 10⁻⁴ S/cm at 473 K for V₂O₅ concentrations of 20 to 60 mol%. The glass 20V₂O₅ * 20SnO * 60TeO₂ was more conductive (σ = 2.6 * 10⁻⁴ S/cm at 473 K) than the glasses V₂O₅ * 20SnO * (80 - X)TeO₂ with X=30 and 40 mol% (σ = -1.0 to 1.4 * 10⁻⁴ S/cm at 473 K). The electric conduction was attributed to adiabatic small-polaron hopping for V₂O₅ ≥ 50 mol% and non-adiabatic small-polaron hopping for V₂O₅ ≤ 50 mol%. The SnO content is contributed to increase basicity and decrease activation energy. The polaron bandwidth / ranged from 0.02 to 0.07 eV depending on the V-V ion spacing. The estimated carrier mobilities were remarkably small: 1.3 * 10⁻⁶ to 4.5 * 10⁻⁵ cm²/(Vs) at 473 K. This small mobility confirmed the small-polaron hopping conduction mechanism. The carrier density was evaluated to be 2.1 * 10¹⁹ to 2.1 * 10²¹/cm³ for V₂O₅ concentrations of 20 to 60mol%.