Use of La0.85Sr0.15CrO3 in high-temperature NOx sensing elements

This work focuses on use of the electronically-conducting oxide La0.85Sr0.15CrO3 (LSC) in solid electrolyte-based NOx sensing elements intended for operation at T ∼650 °C. Two different investigations are described, in the first LSC was used as a direct substitute for Pt. The substitution led to decreased sensitivity to NO2 and an enhancement of the NO response, although the NO2 response was still much larger in magnitude and opposite in sign. Fabrication and evaluation of sensing elements with co-planar LSC and Pt electrodes comprised the second investigation. The measured NOx sensing performance of these elements was commensurate with that of the elements fabricated in the first phase of the investigation (e.g., 450 ppmv NO2 in 7 vol% O2 produced ∼50 mV at 600 °C) and the response/recovery times for NO2 sensing were improved. The results indicate that LSC could be useful in these types of sensing elements, both as a substitute for, and in combination with, Pt.