Structural, electrical and dielectric characterization of TeO 2 –WO 3 –Y 2 O 3 –Er 2 O 3 –Yb 2 O 3 glasses

Abstract TeO 2 based glasses with molar composition (70- x - y )TeO 2 –20WO 3 –10Y 2 O 3 – x Er 2 O 3 – y Yb 2 O 3 , where x = 0 and 0.5 mol% and y = 0, 0.5, 1, 2 and 4 mol%, were prepared by the melt quenching technique. At room temperature all the samples are transparent, mechanical and thermally stable. The XRD results showed the amorphous nature of all the samples and the Raman spectra showed a band distribution related with Te O and W O bond vibrations. The introduction of WO 3 results in a bandwidth substantially larger when compared to SiO 2 based glasses and even other TeO 2 based glasses, making this vitreous system promising for Raman optical amplification. In this work, the measurement and analysis of the electrical properties of this glass system was made. It was found that the hopping of small radius polarons, for small concentrations of networks modifiers, is the dominant process in the charge transport mechanism for the dc conductivity. For higher concentrations of ions structurally inserted in the glass network, the ionic conductivity starts to have an important role in the transport mechanism. The ac conduction mechanism was attributed to a dipolar process between the interstitial modifier cations and the nonbridging oxygen ions. For all samples, the dielectric constant is practically independent of the temperature and the frequency. This quantity tends to decrease with the increase of the concentration of Yb 3+ cations. No dielectric relaxation phenomenon was observed in the temperature and frequency measurement range.