Heterogeneous ceramics formed by grain boundary engineering |
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Authors: | D Ivanova E M C L G P Lima A Kovalevsky F M L Figueiredo V V Kharton F M B Marques |
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Institution: | (1) CICECO/Ceramics and Glass Engineering Department, University of Aveiro, 3810-193 Aveiro, Portugal;(2) School of Technology and Management, Instituto Politécnico de Viana do Castelo (IPVC), 4900-348 Viana do Castelo, Portugal;(3) Science and Technology Department, Open University, 1269-001 Lisbon, Portugal |
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Abstract: | Two examples were selected to emphasize the potential of grain boundary engineering in the performance design of heterogeneous
ceramics. Gadolinium-doped ceria-based powders were co-fired with additions of silica, and silica and lanthanum oxide, to
test the silica scavenging role of lanthanum. The formation of one ionic conducting secondary phase, instead of an insulating
phase, was attempted. The structural, microstructural, and electrical characterization of these samples confirmed the formation
of one apatite-type lanthanum silicate-based phase and a significant enhancement of the grain boundary conductivity of these
materials. One second approach addressed the formation of one mixed conductor, with electronically conductive grain boundaries,
surrounding the grains of one lanthanum gallate-based electrolyte (core-shell type microstructure). Fe-doped grain boundaries
were formed by selective Fe-diffusion (thermally assisted) from lanthanum ferrite screen printed layers. Combined microstructural
and electrical characterization showed that the adopted solution was also effective. |
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Keywords: | Ceria Composite electrolytes O conductors Mixed conductors |
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