Electrical conductivity and hopping conduction mechanism by VRH model in halide modified tellurite glasses

Electrical properties of halide doped tellurium glasses with composition 60TeO(2)-(25-x) Bi2O3-15B(2)O(3)-x ZnCl2, where x varies from 0 to 20 with step-size 5 has been studied in frequency range 10(-)(1) Hz-10(5) Hz and temperature range of 200 degrees C-300 degrees C. The frequency-dependent conductivity was found to obey Almond-West's universal powers law and parameters such as frequency exponent (s), DC conductivity, and crossover frequency were obtained by fitting the ac conductivity experimental data with Almond-West's universal powers law. Based on estimated s values the electrical conduction model was depicted, and it was found that the correlated barrier hopping (CBH) model provides a pretty realistic depiction of the primary AC conduction mechanism. Further, the migratory enthalpy (H-m) and the enthalpy required to remove the cation from its initial position near a charge-compensating centre (H-f) were calculated. Further, Variable range hopping, or VRH, was found to be the process by which charges move between localized states. The electric modulus (M '') fitting with the Kohlrausch-Williams-Watts (KWW) function revealed non-Debye-type relaxation in the examined glass samples. Activation energy estimated from conductivity (1.13-1.20 eV), and electric modulus (1.13-1.22 eV) analysis are in good agreement indicating that polarons had to overcome a constant energy barrier throughout both the relaxation and conduction phases. One master curve was produced for all compositions and temperatures as a result of an impressive convergence in the scaling spectra of the AC conductivity and electric modulus (M ' and M ''). Therefore, it was concluded that neither temperature nor composition impacted the conduction or relaxation mechanisms seen in the glass samples under study. The dielectric properties studies suggested non-debye type behavior.