Effect of lead oxide on the electrical transport properties of lithium-iron-borate glasses

The electrical conductivity and dielectric properties of the glass system (70-x) B2O3-(x) Pb3O4-10Fe(2)O(3)-20Li(2)O [where 0 <= x <= 35] have been investigated in the temperature range from 300 to 530 K, at four fixed frequencies [0.12, 1, 10, and 100 kHz]. Ac conductivity is found to obey the universal relation, sigma(omega) = A omega(s), where s is the frequency exponent factor and its value is less than unity. Investigation of sigma(ac) results and the s factor reveals that the polarons hopping over barrier between Fe2+ and Fe3+ ions is the probable applicable mechanism for sigma(ac) for these glasses. The dc activation energy values are found to increase from 0.67 to 1.61 eV as the lead oxide content increases. These remarks are explained using Mossbauer Effect (ME) spectrometer and molar volume calculations. The observed higher records of the dielectric constant for the lead-free sample could be attributed to some precipitated iron in the form of alpha-Fe2O3, which increases the polarized space charges in the glass network.

Automated summary

The study investigated the electrical conductivity and dielectric properties of glass systems with and without lead, finding that the mechanism of polarons hopping applied to the ac conductivity of lead-containing glasses. The DC activation energy was positively correlated with lead oxide content, and the higher dielectric constant of lead-free samples was attributed to increased polarized space charges in the glass network due to the presence of precipitated iron.