Structural and electrical characterization of semiconducting xCuO-(100-x)TeO₂ glasses

Structural, thermal and electrical properties of semiconducting copper tellurite glasses: xCuO-(100-x)TeO₂ (x = 30, 40 and 50 mol%) were studied by neutron diffraction, Raman spectroscopy, thermal analysis and two probe electrical conductivity measurements. Reverse Monte Carlo simulations of the neutron structure factors found that Te[sbnd]O and Cu[sbnd]O bonds have equal lengths of 1.94 Å and that both Te and Cu ions exist in structural units of similar size and geometry. The average Cu[sbnd]O co-ordination decreases from 3.72 to 3.68, while the Te[sbnd]O co-ordination decreases from 3.48 to 3.34 on increasing the CuO concentration from 30 to 50 mol%. The electrical conductivity increases from 2.96 × 10⁻⁹ Ω⁻¹ m⁻¹ to 1.25 × 10⁻⁷ Ω⁻¹ m⁻¹ with an increase in CuO concentration from 30 to 50 mol%. The increase in CuO mol% increases the Cu[sbnd]Cu coordination number from 0.68 to 1.26 and promotes electronic hopping between the adjacent Cu sites.