Mixed Ionic and Electronic Conduction in TeO₂-ZnO-V₂O₅ Glasses towards Good Dielectric Features

The melt-quenching technique was used to synthesize tellurite glasses of the chemical composition 80TeO₂-(20-x) ZnO-xV₂O₅. X-ray diffraction (XRD) patterns indicate the amorphous nature of the prepared glasses. Raman and FTIR measurements demonstrate a progressive substitution of the Te-O-Te linkages by the Te-O-V bridges and the formation of VO₄ and VO₅ units by a change of the vanadium coordination due to the higher number of oxygens incorporated by further addition of V₂O₅. The AC conductivity was investigated in the frequency range of 40 Hz to 10⁷ Hz between 473 K to 573 K. A good coherence of the AC conductivity was found using a model correlating the barrier hopping (CPH) and the dominant conduction process changes from ionic to polaronic with the addition of V₂O₅. The dielectric constant exhibits high values in the range of lower and medium frequencies. Both variations of the electric modulus and the dielectric loss parameters with frequency and temperature showed a relaxation character mainly assigned to the vanadate phases. The electric modulus displays a non-Debye dielectric dispersion and a relaxation process. The present results open the door to future zinc-tellurite glasses-doped vanadium exploitation as a potential electrolyte-based material for solid-state batteries.