Dhankhar S.,Guru Jambheshwar University of Science and Technology |
Kundu R.S.,Guru Jambheshwar University of Science and Technology |
Parmar R.,Maharshi Dayanand University |
Murugavel S.,University of Delhi |
And 3 more authors.
Solid State Sciences | Year: 2015
The ac conductivity of tellurium based quaternary glasses having composition 60 TeO2 - 10 ZnO - (30 g' x) B2O3 - xBi2O3; x Combining double low line 0, 5, 10, 15 and 20 has been investigated in the frequency range 10g'1 Hz to 105 Hz and in the temperature range 483 K-593 K. The frequency and temperature dependent ac conductivity increase with increase in bismuth content and found to obey Jonscher's universal power law. The dc conductivity, crossover frequency and frequency exponent have been estimated from the fitting of the experimental data of conductivity with Jonscher's universal power law. In the studied glasses the ac conduction may be described by overlapping of large polaron tunneling model. The activation energy is found to be decrease with increase in bismuth content and variable range hopping (VRH) proposed by Mott with some modification suggested by Punia et al. is more or less suitable to explain dc conduction. The value of the stretched exponent (β) obtained by fitting of Mg€3 reveals the presence of non-Debye type of relaxation in the presently studied glass samples. Scaling spectra of electric modulus (M′ and Mg€3) collapse into a single master curve for all the compositions and temperatures. The values of activation energy of electric modulus (ER) and conduction (W) are nearly equal for all the studied glasses, indicating that the polaron have to overcome the same energy barrier during conduction as well as relaxation processes. The conduction and relaxation process in the presently studied glass samples are composition and temperature independent. © 2015 Elsevier Masson SAS.