FeSrTiO3-based resistive oxygen sensors for application in diesel engines

SrTi0.4Fe0.6O2.8 (STFO60) powders were prepared by Self-propagating High-temperature Synthesis (SHS) and subsequent Ball-Milling (BM) treatment and then deposited on interdigited alumina substrate by screen-printing to fabricate a planar resistive oxygen sensor for direct injection (DI) diesel engines. The electrical characteristics and response to oxygen of the STFO60 sensor have been carefully examined first in a bench system with synthetic gases thus simulating diesel exhaust composition. Results obtained highlighted the promising performances of the sensor in terms of temperature resistance independence as well as sensor response at the high oxygen concentrations typical of diesel engines. Cross-sensitivity tests also indicated that the sensor response is not influenced by main components in the exhausts, such as HC, CO2, NOx, CO. The STFO60 sensor was then tested as oxygen probe during road tests on a diesel engine car, thus comparing the acquired sensor signals with those ones of a commercial lambda probe. Road tests confirmed the good performances of the resistive sensor also in real driving conditions.