The effect of non-bridging oxygen on the electrical transport of some lead borate glasses containing cobalt

Abstract

Abstract The effect of reducing oxygen in glass network on the electrical conductivity of system 50 B2O3 − 20 Pb3O4 − 10 Co3O4 − (20 − x)CaO − xCaCl2 (0 ≤ x ≤ 20 mol%) has thoroughly been investigated. This reduction was created by substituting oxygen ions with chloride ions. The measurements were conducted in the temperature range 320–560 K for fixed frequencies 0.1, 1, 10 and 100 kHz. It was found that at low temperatures, the dc conductivity (σ dc) is lower than the measured ac conductivity σ(ω), whereas σ(ω) and σ dc became equal at high temperature for all frequencies. The ac, dc conductivity as well as dc activation energies decrease with the gradual increase of CaCl2 content. The ac conductivity and the frequency exponent data showed that the correlated barrier hopping of electrons between both of oxidation states of cobalt ions (Co2+ and Co3+) is the most probable mechanism. The dielectric constant and the dielectric loss of the present glass system can be fitted to the Cole–Cole equation for all frequencies and temperatures.