Physical and dielectric properties of boro-tellurite glass doped with cobalt and iron oxides

The glass system with composition [(TeO2)0.7(B2O3)0.3]1-x[Co3O4]x with x= 0.01, 0.02, 0.03, 0.04, 0.05 and 0.06, and {[(TeO2)0.7(B2O3)0.3]0.95[Co3O4]0.05}1-y{Fe2O3}y with y= 0.01, 0.02, 0.03, 0.04, 0.05 and 0.06 has been successfully prepared by the melt quenching technique. The amorphous nature of glass system was determined by using XRD measurement. The glass transition temperature, (Tg), was determined using the DTA technique at room temperature. Density of variation glasses sample was measured at room temperature using the Archimedes technique. The values of molar volume were calculated from density data. The infrared absorption spectra of the glasses sample in the wavenumber range of 280-4000 cm-1 were recorded by using Fourier Transform Infrared Spectroscopy. The magnetic behaviour in the glass system was studied using VSM (vibrating sample magnetometer) at room temperature with magnetic field range ±15kOe. The susceptibility was determined from the relationship between magnetic field, H (Oe) and magnetic moment/mass, M (emu/mass). The magnetization, of the glass sample increases with increasing of magnetic field, H. Dielectric properties have been investigated in the frequency range 10-2 to 103 Hz and temperature range 30 °C-200 °C. From this measurement, the dielectric properties such as dielectric permittivity, ε’, and dielectric loss, ε”, was determined. The ɛ’ and ɛ” of glasses sample increases with temperature and decreases with frequency. The activation energy of dielectric properties was determined from normalization curve using the Arrhenius equation. The activation energy of both glasses sample increases with increasing cobalt and iron oxide content. The conductivity, σ of glasses sample also been calculated from equation, . The value of dc conductivity, σdc was determined from “ac universal power law”, and the value activation energy of σdc, has been calculated using the Arrhenius implied. The activation energy of σdc was increased with increasing of cobalt and iron oxide. The activation energy of dc conductivity was almost equal with dielectric loss relaxation indicating the same species took part in both the process. The dielectric behaviour of these glass systems also has been analyzed using electric modulus, M and impedance, Z, formalism. The graph of M” and Z” peaks were found overlapping each other. This behaviour indicated a long range conductivity process appears in this glasses sample. For first series glasses sample, the value of activation energy of impedance plot, Z” vs. Z’, increases with increasing of cobalt oxide content. For the second series glass samples, the curve of Z” vs. Z’ plot will compose of two semicircle with increases of iron oxide content. The activation energy for second series glass samples decreases with increasing iron oxide content.

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