eTheses Repository

# Synthesis and characterisation of d-Bi2O3 related materials stabilised by substitutions of Ca, Ga, Nb and Re.

Thompson, Maria (2010)
Ph.D. thesis, University of Birmingham.

 PDF (7Mb)

## Abstract

The work reported in this thesis is based around substitutions into bismuth oxide, which has proven to be highly adaptable chemically as it can accommodate a wide variety of substituents. The synthesis and characterisation of stabilised $$\delta$$-Bi$$_2$$O$$_3$$ related materials containing small amounts of Ca, Ga, Nb and Re are described. A body of work is presented exploring the structural and physical properties of such materials, characterised by neutron powder diffraction, X-ray powder diffraction, electron diffraction, extended X-ray absorption of fine structure measurements, differential thermal analysis and impedance spectroscopy. The structure of two new fluorite-related materials, Bi$$_6$$Ca$$_3$$ReO$$_{15.5}$$ and Bi$$_{10}$$Ca$$_5$$ReO$$_{23.5}$$, were studied. Bi$$_6$$Ca$$_3$$ReO$$_{15.5}$$ formed a face-centred cubic fluorite-related structure and Bi$$_{10}$$Ca$$_5$$ReO$$_{23.5}$$ a body-centred cubic material that is a 4 x 4 x 4 superstructure of the Bi$$_6$$Ca$$_3$$ReO$$_{15.5}$$ phase. The structure of novel isostructural materials Bi$$_{20}$$Ca$$_7$$NbO$$_{39.5}$$ and Bi$$_{10.75}$$Ca$$_{4.375}$$GaO$$_{22}$$ were also investigated. Both materials formed distorted $$\delta$$-Bi$$_2$$O$$_3$$ related superstructures, derived as a monoclinic supercell based on a fluorite-related hexagonal subcell. Detailed structural analysis and local environments of cations in the ordered monoclinic fluorite-related superstructure of Bi$$_9$$ReO$$_{17}$$ are also explored. All materials synthesised in this thesis have structures related to that of $$\delta$$-Bi$$_2$$O$$_3$$, which is known to have high oxide ion conducting properties at elevated temperatures. Oxide ion conducting properties are therefore also described.

Type of Work: Ph.D. thesis. Greaves, Colin (Professor) Colleges (2008 onwards) > College of Engineering & Physical Sciences School of Chemistry QD Chemistry University of Birmingham 1185
This unpublished thesis/dissertation is copyright of the author and/or third parties.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.

Repository Staff Only: item control page