Investigation of chemisorbed oxygen, surface segregation and effect of post-treatments on La_0.8Sr_0.2MnO₃ powder and screen-printed layers for solid oxide fuel cell cathodes

Noémie Caillol (1, 2, 3) , Michèle Pijolat (1, 2, 3) , Elisabeth Siebert (4)

1 LPMG-EMSE - Laboratoire des Procédés en Milieux Granulaires
2 ProcESS-ENSMSE - Département Procédés et évolution des systèmes avec solides
3 SPIN-ENSMSE - Centre Sciences des Processus Industriels et Naturels
4 LEPMI - Laboratoire d'Electrochimie et de Physico-chimie des Matériaux et des Interfaces

In order to better understand the mechanism of the reaction of oxygen reduction at the surface of strontium doped lanthanum manganites (LSM) cathodes in solid electrolyte fuel cells (SOFC), the surface properties of La_0.8Sr_0.2MnO₃ powders and screen-printed layers have been characterised by various techniques.

Strontium enrichment at the surface has been evidenced by X-ray photoelectron spectroscopy according to the conditions of annealing (temperature, oxygen pressure) and polarisation treatments of the samples.

The interaction between oxygen and La_0.8Sr_0.2MnO₃ for SOFC cathodes has been studied by thermo-programmed desorption, in situ infrared spectrometry and calorimetry. The results indicate that various adsorbed oxygen species may exist on the surface of LSM depending on temperature.

The presence of various adsorbed oxygen species and the surface Sr segregation are important factors to consider in the mechanism of oxygen reduction at LSM SOFC cathodes since they could be responsible for many discrepancies between the interpretations that can be found in the literature data.

Mots clés: LSM; SOFC; Adsorbed oxygen species; Screen-printing; Segregation

Domaines: Matériaux; Génie des procédés

Noémie Caillol, Michèle Pijolat, Elisabeth Siebert. Investigation of chemisorbed oxygen, surface segregation and effect of post-treatments on La_0.8Sr_0.2MnO₃ powder and screen-printed layers for solid oxide fuel cell cathodes. Applied Surface Science, 2007, 253 (10), pp. 4641-4648. ⟨10.1016/j.apsusc.2006.10.019⟩. ⟨hal-00333715⟩