Performance of solid electrolyte oxygen sensor with solid and liquid reference electrode for liquid metal

Abstract

As the performance of the solid electrolyte oxygen sensor, the effects of an amount of residual air in the reference electrode (RE) on the stabilization time to an equilibrium condition was investigated for solid electrolyte oxygen sensors with solid Fe–Fe3O4 RE and liquid metal Bi–Bi2O3 RE in the tests in an air atmosphere with constant oxygen potential. It was found that the reduction of the volume of the gas region in the reference compartment by an inert material make the stabilization time of RE shorter, where the stabilization time is the time required to the changes from initial setup conditions to the equilibrium conditions in the reference electrode sides. Under the equilibrium conditions of the oxygen potentials both in the solid Fe–Fe3O4 RE and liquid metal Bi–Bi2O3 RE, the sensor output showed the stable cell potential which agreed well with the theoretical one given by the Nernst equation. It was also found that the stabilization time of solid Fe–Fe3O4 RE was shorter than that of liquid metal Bi–Bi2O3 RE in the air atmosphere. The sensors with the solid Fe–Fe3O4 RE and liquid metal Bi–Bi2O3 RE were tested in the atmospheres of a static molten lead-bismuth eutectic (LBE) where the oxygen potentials were controlled to be those with the PbO and Fe3O4 formation potentials by mass-exchanger method. Under the equilibrium conditions of oxygen potential both in the reference electrodes and in the molten LBE atmospheres, the sensor output showed the stable cell potential which agreed well with the theoretical ones given by the Nernst equation.