Effect of the Iron Ion Doping in LaCoO₃ Perovskite, Both in Powders and in Sintered Samples Obtained from Combustion Reaction and Solid State Route

Abstract:

The aim of this work is to show the effect of the iron ion doping in LaCoO₃ perovskite, both in powders and in sintered samples obtained from combustion reaction and solid state route. The phase formation and particle morphology and particle size distribution of the powders were analysed by XRD, SEM and sedimentation techniques, respectively. Relative density, microstructure (secondary phases and grain size) and pore size distribution of LaCo_1-xFe_xO₃ sintered ceramics were investigated by SEM/EDS and Hg porosimetry analysis. Although LaCo_1-xFe_xO₃ powders obtained from the combustion reaction exhibited smaller grain sizes when sintered at high temperatures, they showed a higher volume fraction of secondary phases. The presence of these crystalline phases in addition to the desired perovskite affected the microstructure acting as grain growth inhibitors by grain boundary pinning. It is believed that by observing three grain junction pores that the LaFeO₃ phase has a smaller dihedral angle than LaCoO₃. This fact would explain why LaFeO₃ presented a smaller driving force for sintering with a higher tendency of pore and inclusion coarsening at higher temperatures (1400°C).

• Periodical: Advanced Materials Research (Volumes 1120-1121)
• Pages: 58-63
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.1120-1121.58
• Online since: July 2015
• Authors: Daniel Véras Ribeiro*, Gustavo R. Paula, Márcio Raymundo Morelli
• Keywords: Combustion Reaction, Grain Growth, LaCo_1-xFe_xO₃, Sintering

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