Tritium Conductivity and Isotope Effect in Proton‐Conducting Perovskites

Abstract

The tritium ion conductivities of and have been measured by ac impedance analysis. The high tritium conductivity of these perovskites could potentially lead to their application as an electrochemical membrane for the recovery of tritium from tritiated gas streams. The conductivities of these perovskites, along with , were also measured in hydrogen‐ and deuterium‐containing atmospheres to illustrate the isotope effect. For the strontium zirconate and barium cerate samples, the impedance plot consists of two clearly resolved arcs, a bulk and a grain boundary arc, in the temperature range 50–350°C. However, for the strontium cerate sample, the clear resolution of the bulk conductivity was not possible and only the total conductivity was measurable. Thus, the isotope effect was clearly established only for the strontium zirconate and barium cerate samples. The decrease in bulk conductivity with increasing isotope mass was found to be a result of an increase in the activation energy for conduction accompanied by a decrease in the pre‐exponential factor. Since the concentration of the mobile species (H+, D+, or T+) should remain relatively constant at T < 350°C, this increase in activation energy is directly attributable to the increased activation energy for the isotope mobility. © 1999 The Electrochemical Society. All rights reserved.