Inferring bubble volume fraction in a glass melt through in situ impedance spectroscopy measurements

Abstract We evaluated the feasibility of inferring the bubble volume fraction ( ϕ _b ) in a melt by employing in situ impedance spectroscopy measurements. This idea stems from the effective medium theory, in which the ionic conductivity of a biphasic material can be determined from the isolated contribution of each constituent phase and their respective volumetric content. Therefore, we investigated the overall electrical conductivity of a borosilicate melt doped with cerium‐IV oxide at a constant temperature (1273 K), in which O ₂ gas production takes place. To validate the use of this proposed technique, postmortem bubble volume fraction analyses on samples synthesized following the same procedure were conducted by apparent density and impedance spectroscopy measurements at low temperatures (below T _g ). A comparison of these postmortem and in situ techniques is presented. Despite some discrepancies observed between the bubble volume fractions estimated by these different methods, the main results demonstrate the technical viability of this in situ approach. In situ impedance spectroscopy presents advantages in terms of pre‐synthesis duration and sample preparation, and the information is obtained at high temperatures, eliminating the possible influence of the cooling stage.