The control of very low oxygen partial pressures with stabilized zirconia cell

Abstract

Control of very low oxygen partial pressures was performed in the range of 10 −21-10 −24 Pa at 750°C by pumping oxygen into the purified hydrogen stream with a stabilized zirconia cell. The oxygen partial pressures were monitored by a stabilized zirconia sensor. The stabilized zirconia oxygen sensor was calibrated by H 2-CO 2 gas buffer mixture in the range of oxygen pressure from 10 −17 to 10 −21 Pa, and oxygen partial pressures below 10 −21 Pa were measured by extrapolating the calibration line to very low oxygen partial pressures. The lowest oxygen partial pressure controlled was 10 −24 Pa at 750°C, which was limited by gas leaks in the system and also by the reduction of the ionic transference number in solid electrolyte used as the oxygen pump.