Ion-polaron interaction in modified tellurite glasses

Abstract

Glasses formed by a mix of oxides are interesting for many technological applications. Their physical properties change according to the constituent oxides. Every oxide creates a three-dimensional network built by corner connected oxygen polyhedral, with different coordination number. The oxides can be either glass formers or glass modifiers, granting the final product specific characteristics. Thus, it is of utmost importance which oxides to incorporate to the original mix. In this work, we analyze the polaron conductivity in the presence of large alkaline cation concentrations. We studied oxide glasses formed by TeO2 modified by the incorporation of transition metal oxides: V2O5, Cu2O, and MoO3. Additionally, such tellurite glasses contain Na2O or MgO. Holstein 1 proposed in 1959 for materials with low charge carrier mobility (<0.1cm/V.s) that an electron trapped in the lattice would not be able to move unless the lattice could move together with it. Such proposal gave birth to the polaron concept. The explanation is that the charge carrier (the electron) induces a dipole moment on its neighboring and both move together, i.e. the polaron. Therefore, polaron conductivity involves the displacement of polaron in a material. When the material is a glass the charge carrier and the distortion in its surrounding move through the glassy matrix. For that reason, in this work we study how the presence of alkaline and alkaline earth cations affects the polaron transportation in the tellurite glasses.