Response kinetics of temperature-independent resistive oxygen sensor formulations: a comparative study

This contribution compares the response kinetics of two temperature-independent resistive oxygen sensor formulations: LaCu0.3Fe0.7O3−δ (LCF) and La0.05Sr0.95Ti0.65Fe0.35O3−δ (LSTF). Screen-printed thick film sensor specimens were prepared. Sensor characteristics towards oxygen were determined, and additional measurements in the frequency domain were realized: the former indicate a fast and nearly temperature-independent response of LCF and LSTF compositions in the temperature range between 750 and 900 °C. The latter allow conclusions on the underlying sensing mechanism. Whereas oxygen sensitivity of LSTF is exclusively controlled by a reaction step, response of LCF is governed by reaction only at lower temperatures. At higher temperatures, a diffusion process becomes limiting. This different behavior is attributed to different microstructures of the sensitive films.