Show simple item record

Files in this item

Thumbnail

Item metadata

dc.contributor.advisorIrvine, John T. S.
dc.contributor.authorOvalle, Alejandro
dc.coverage.spatial183en
dc.date.accessioned2008-12-02T14:57:58Z
dc.date.available2008-12-02T14:57:58Z
dc.date.issued2008-02-21
dc.identifieruk.bl.ethos.552095 
dc.identifier.urihttps://hdl.handle.net/10023/567
dc.description.abstractA new family of perovskite titanates with formulae La4+nSr8-nTi12-nMnnO38 and La4Sr8Ti12-nMnnO38-δ have been investigated as potential fuel electrode materials for SOFCs. The series La4+nSr8-nTi12-nMnnO38 present layered domains within their structure. As such layers appear to have a large negative effect over the electrochemical properties only a few compounds have been characterised. The series La4Sr8Ti12-nMnnO38-δ present a rhombohedral (R-3c) unit cell at room temperature which becomes cubic when increasing the temperature up to 900°C both in air and in reducing conditions. The primitive volume correlates with the oxygen content for the reduced samples. TGA and magnetic studies have revealed that the Mn present is mainly as Mn⁺³. Preliminary HRTEM investigations have revealed that some crystallographic shears distributed randomly within a perovskite matrix remain in the structure, which implies that the oxygen overstoichiometry is compatible with rhombohedral distortions in the oxygen sublattice. Mn substitution does not have a large impact on the bulk conductivity of the phases studied, which remains close to the values observed in other related titanates, although the grain boundary contributions are largely improved. Relatively low polarisation resistances were observed under both hydrogen and methane conditions for the lowest n compounds of the series. The anodic overpotential for n=1 was fairly low to those reported in the literature for other materials and especially for titanate-based anodes, i.e. a value of 55mV at 0.5A/cm2, at 950°C, under wet hydrogen was obtained. Additionally, a value 72mV was obtained in the same conditions under methane. These values indicate that the use of Mn as dopant for perovskite-related titanates enhanced electrochemical performance of these anodes, especially at high temperatures.en
dc.format.extent2675 bytes
dc.format.mimetypeapplication/pdf
dc.language.isoenen
dc.publisherUniversity of St Andrews
dc.subjectSOFCen
dc.subjectAnodesen
dc.subjectPerovskitesen
dc.subject.lccTK2931.O8
dc.subject.lcshSolid oxide fuel cellsen
dc.subject.lcshAnodesen
dc.subject.lcshManganese compoundsen
dc.subject.lcshTitanatesen
dc.subject.lcshPerovskiteen
dc.titleManganese titanium perovskites as anodes for solid oxide fuel cellsen
dc.typeThesisen
dc.type.qualificationlevelDoctoralen
dc.type.qualificationnamePhD Doctor of Philosophyen
dc.publisher.institutionThe University of St Andrewsen


This item appears in the following Collection(s)

Show simple item record