Dielectric properties of the ternary TeO2/Nb2O5/ZnO glasses

Glasses of the system TeO2/Nb2O5/ZnO containing different concentration of ZnO (ranging from 5 to 20mol%) were prepared. The dielectric properties over wide ranges of frequencies and temperatures were investigated as a function of ZnO content by impedance spectroscopy measurements. The impedance spectra of the present glasses were modeled by appropriate equivalent circuit. The dielectric constant has a value of 66 for the 85TeO2/10Nb2O5/5ZnO glass, which is three times larger than that of pure TeO2 glass and other binary, e.g. TeO2/ZnCl2, tellurite glassy systems. The results have been analyzed in light of varying NbO6 octahedra and NbO4 tetrahedra of niobium oxide as zinc oxide varies from 5 to 20mol%. The relaxation properties of the investigated glasses are presented in the electric modulus formalism, where the relaxation time and the respective activation energy are determined.