Microstructural Evolution During Sintering of Lanthanum Calcium Ferrite Perovskite Ceramics
Dr. Darryl Butt
Lanthanum calcium ferrite (LCF) is a perovskite ceramic that may be used for syngas production, solid oxide fuel cell cathodes, and oxygen sensors because of its high temperature stability, creep resistance, and high oxygen mobility. In this study, the microstructural evolution of the LCF system was investigated. Samples with varying ratios of calcium to lanthanum from 0:1 to 1:0 were fabricated by ball milling lanthanum(III) oxide, calcium oxide, and iron(III) oxide together. Individual samples were cold-pressed, and then fired at 1250°C. To reveal the microstructure, each pellet was polished, and then annealed at 1100°C. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) have shown various morphological and microstructural changes with the addition of calcium into the system. The first observation was an initial grain size reduction when calcium was introduced. Further substitution showed the enhancement of grain growth. Secondly, there may be a possible co-existence of the rhombohedral and orthorhombic structures at 10%, 20% and 30% calcium content. Finally, an elongated Grenier phase is formed at 40% calcium.
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