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Investigating the controlled oxidation of manganese oxides with the Brownmillerite structure

Hassan, Nipula (2010)
M.Res. thesis, University of Birmingham.

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Abstract

Brownmillerite structures have received much attention due to their defect perovskite structure and potential for interesting magnetic behaviour and ionic conductivity. This thesis describes an initial investigation into the potential of manganese containing Brownmillerite phases, with the stoichiometry (Sr2-xCax)MnGaO5+δ, to display significant mixed conductivity and interesting magnetic properties by forming mixed manganese valence. Significant mixed valency in manganese has not previously been reported in Sr2MnGaO5, Ca2MnGaO5 or SrCaMnGaO5. Oxidation of Sr2MnGaO5, nominally Mn3+ to Sr2MnGaO5.5, nominally Mn4+, occurs rapidly without intermediates, whereas both Ca2MnGaO5 and SrCaMnGaO5 show no significant oxidation at atmospheric pressure. This work centres on the solid solution between these extremes to analyse structural changes and the potential for partial oxidation of manganese. Neutron diffraction has been carried out on these samples to investigate the structures and oxygen uptake.

Type of Work:M.Res. thesis.
Supervisor(s):Wright, Adrian
School/Faculty:Colleges (2008 onwards) > College of Engineering & Physical Sciences
Department:Chemistry
Keywords:Brownmillerite; Perovskite; Magnetoresistance; (Anti)Ferromagnetic Neutron; Diffraction; Sr2-xCaxMnGaO5
Subjects:QD Chemistry
Institution:University of Birmingham
ID Code:689
This unpublished thesis/dissertation is copyright of the author and/or third parties. The intellectual property rights of the author or third parties in respect of this work are as defined by The Copyright Designs and Patents Act 1988 or as modified by any successor legislation. Any use made of information contained in this thesis/dissertation must be in accordance with that legislation and must be properly acknowledged. Further distribution or reproduction in any format is prohibited without the permission of the copyright holder.
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