Temperature programmed oxygen desorption of the perovskites series Ln0.65Sr0.3Mn0.8Co0.2O3 (Ln=La-Gd)

Abstract

Abstract. Temperature programmed 02 desorption (hereafter denoted reduction, TPR) in a high vacuum system equipped with a mass spectrometer was used to investigate the oxygen loss as a function of temperature in perovskites materials of the type Lno.65Sr~3Mn0.sCoo.203 (Ln = Im--Gd), which are important as potential electrode materials for solid oxide fuel cells (SOFC). The materials were prepared either by spray drying as described in [l] or via the Pechini method [2] for the perovskites with Ln = Nd-Gd.The TPR experiments were carried out at temperatures 300-1000 K with various heating rates 13 in order to determine the onset of reduction and the activation energy of reduction for each perovskite. The experiments were carried out in an ultra high vacuum chamber (base pressure 10 t~ mbar after baking) equipped with a quadrupole mass spectrometer [3,4]. Additional oxygen adsorption was attempted at several adsorption temperatures but no discrete oxygen desorption peaks were observed before the onset of reduction. Pro.6sSr0.3Mno.~Coo.203 was tound to have the lowest reduction activation energy (149+19 kJ/mol) and the lowest temperature, TR, for onset of reduction (750 K). On the other hand Gdo.65Sro.3Mno.sCoo.203 was found to have the highest reduction activation energy (232+38 kJ/mol) while the TR was about 850 K. The reduction activation energies follow the sequence Pr <Sm < Eu < La < Nd < Gd while the T R values follow the sequence Pr < La < Gd < Eu <Sm < Nd.

Release and uptake of oxygen in mixed-conducting SOFC cathode materials measured by temperature-programmed methods

“…Looking at the desorption profiles observed previously [14], the onset temperatures are in the same range as in the TPR spectra of Fig. 4.…”

Potentiometric NO2 Sensors Based on Thin Stabilized Zirconia Electrolytes and Asymmetric (La0.8Sr0.2)0.95MnO3 Electrodes

“…La 0.8 Sr 0.2 MnO 3 (LSM) has been widely studied as a catalyst to decompose NO x [14,15,16,17,18,19]. Additionally, LSM has also been considered as an ideal cathode material, which can be co-fired with thin YSZ electrolytes in solid oxide fuel cells (SOFCs) [20,21,22].…”