Strontium-doped Lanthanum Manganite Synthesis for Solid Oxide Fuel Cells Cathode

摘要

Strontium-doped lanthanum manganite perovkiste oxides (LSM) are the most popular materials for cathodes in solid oxide fuel cells (SOFC). These materials show excellent electrocatalytic activity for oxygen reduction at high temperatures and are stable at operation conditions. In this work La0.85Sr0.15MnO3 (LSM 15) and La0.78Sr0.22MnO3 (LSM 22) were prepared by the Pechini method The samples were calcinated at several conditions changing temperature and dwell time. The procedure was adopted to evaluate the LSM crystalline structure development with the objective of finding the favorable condictions to attain powders with better crystalline structure with low calcination temperatures. The samples were characterized by termogravimetric analyses, differential thermal analyses, X-ray diffraction, and specific surface area using BET method and scanning electronic microscopy with field emission electron guns. The thermal analyses showed that the 22% strontium substituted manganite cristallized at lower temperatures. X-ray diffraction patterns confirmed the presence of nanopowders completely crystallized at 700 degrees C. At high temperatures small quantities of La2O3 were also present. The LSM 22 showed during the entire range of temperatures higher specific surface area and smaller particle sizes. The powders calcinated at 600 degrees C, did not show significant variation on the crystallization process for long dwell times.