Comparison of solid metal–metal oxide reference electrodes for potentiometric oxygen sensors in liquid lead–bismuth eutectic operating at low temperature ranges

Potentiometric oxygen sensors with metal–metal oxide reference electrodes including Cu/Cu2O, Ni/NiO and Fe/Fe3O4 were tested in oxygen saturated lead–bismuth eutectic (LBE) over the temperature range from 200 to 450 °C to assess their minimum operating temperature limit. The performance of sensors with the three reference electrodes was compared to that of a sensor with air/lanthanum strontium manganese oxide (LSM) reference electrode using the same solid electrolyte material and measurement setup. The sensor with Cu/Cu2O reference electrode performed well down to 200 °C in oxygen saturated LBE, while those with Ni/NiO and Fe/Fe3O4 showed significant deviations from expected values below 300 °C. Furthermore, the sensor with Cu/Cu2O electrode showed a response to temperature variations as fast as that of the air/LSM electrode over the entire temperature range of interest in liquid LBE.