Electrical and dielectric properties of As-Se glasses doped with uranium

Influence of uranium, added in metallic form, on the density, glass transition temperature, ac and dc conductivities, and static permittivity of vitreous As 2 Se 3 , As 2 Se 7.9 , and Se is investigated. Concentration and temperature dependences of the physical properties are studied over the whole glass-forming region. In glassy As 2 Se 3 , heavy metals are usually incorporated as 4-fold coordinated cations. Therefore, the concentration dependence of the electrical conductivity goes through a minimum. At high concentrations of U (≥0.5 mol%), high conductivities are observed. A distinct minimum of both the static permittivity (at 0.1 mol% U, it decreases by 25 %) and dc conductivity (at 0.2 mol% U, it decreases by 10 -3 times), at low concentrations of U, reflects an extraordinary electrical activity of this impurity in vitreous As 2 Se 3 . Enlargement of glass forming regions in As-Se-U system with increasing Se:As ratio was not confirmed.