Influence of solid electrolyte material selection on electromotive force characteristics of oxygen sensor for lead-cooled fast reactor

Potentiometric oxygen sensors play a crucial role in measuring dissolved oxygen concentration in lead-cooled fast reactors (LFRs). The choice of the solid electrolyte material, including yttria partially stabilized zirconia (YPSZ) and yttria stabilized zirconia (YSZ), exerts a significant influence on the sensors’ performance characteristics. In this study, the Potentiometric oxygen sensors with YPSZ and YSZ solid electrolyte were tested within the oxygen-saturated lead-bismuth eutectic (LBE) at the temperature range from 473 K to 773 K. The ionic conductivities of the solid electrolytes were obtained by alternating current impedance. The crystal phase changes of YSZ and YPSZ were compared by variable temperature XRD. Notably, the oxygen ion channels begin to form in solid electrolytes at 523 K, with full activation occurring at 643 K for YSZ and 723 K for YPSZ. The electromotive force (EMF) of YSZ and YPSZ-sensors possess good accuracy and stability between 623 and 773 K. Below 623 K, the EMF of YPSZ-sensor is consistently deviated from the theoretical value. These variations in activation temperatures are attributed to differences in Y3+ content, resulting in distinct operational temperature ranges for electrolytes.