Investigations of soot combustion on yttria-stabilized zirconia by environmental transmission electron microscopy (ETEM)

Abstract

Environmental transmission electron microscopy (ETEM) equipped with an aberration corrector was used to get further insights into the mechanism of soot oxidation on yttria-stabilized zirconia (YSZ), an O2− ionic conductor. In situ observations, with a resolution of around 1nm, of a “tight” YSZ/real soot mixture were performed at 550°C in the presence of a few mbar of oxygen (2 and 3mbar). Preliminary experiments were conducted to validate that moderate electron beam illumination conditions do not control the soot combustion. Video sequences recorded at 550°C clearly confirmed that bulk YSZ oxygen atoms are the active species for soot oxidation at the soot/YSZ interface as no oxidation takes place without contact. The number of soot/YSZ contact points and their evolution with time are the key parameters for soot oxidation. The contact length between the soot and the YSZ grains could be estimated to be around 20–40nm only.