Electrical properties of copper phosphate glasses II. Dielectric properties

Abstract

The ac and dc electrical properties of the P 2O 5BaOCuO glass system have been measured. TSPC and TSDC experiments and dc conductivity as a function of time indicate the predominantly electronic character of these glasses. The conduction process can be basically explained by a polaron hopping model in an adiabatic regime. Conductivity values which depend on the glass microstructure and switching phenomena are observed. The filamentary-feature of this process suggests a Poole-Frenkel mechanism. A Debye dielectric relaxation non-simple process is deduced from the frequency and temperature dependence of loss tangent and dielectric constant. The activation energies agree with those determinated from dc measurements, suggesting a unique electronic hopping conduction mechanism in both regimes. The ac and dc electrical properties are strongly affected by the glass composition and essentially by the redox Cu +/Cu t ratio. A conduction model accounting for ac and dc behaviour is finally proposed.