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Structural studies of metal doped phosphate glasses and computational developments in diffraction analysis

Moss, Rob M. (2009) Structural studies of metal doped phosphate glasses and computational developments in diffraction analysis. Doctor of Philosophy (PhD) thesis, University of Kent.

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Abstract

The thesis focuses on the analysis and determination of the structure of various metal doped phosphate glasses, which are of interest for their potential biomedical properties. The structures have been determined principally by X-ray and neutron diffraction but are also supported by complimentary X-ray absorption spectroscopy measurements and computational modelling. Such studies contribute to about half of the work presented in this thesis. Among the glasses of interest are silver-doped calcium sodium phosphates, which exhibit antimicrobial properties when the Ag+ ions are released over time in an aqueous environment. The advanced probe technique of neutron diffraction with isotropic substitution (NDIS) has been applied to elucidate the structural role of silver in these glasses. The results revealed that silver occupies a highly distorted octahedral environment analogous to that in crystalline Ag2SO4. Another glass study herein is associated with zinc titanium calcium sodium phosphate, which is biomedically interesting since the release of Zn2+ ions is shown to enhance cell attachment and proliferation. Structural analysis of multi-component glasses such as these tends to be difficult, but diffraction techniques and X-ray absorption spectroscopy have been used together to reveal the cation first neighbour coordination environments. The other significant element of the work presented here has been the development of data analysis techniques, with the emphasis on the creation of a program, which allows co-fitting of X-ray and neutron diffraction data of amorphous (and potentially crystalline) data. The code is written in MATLAB and makes use of the Nelder-Mead simplex method to minimise a set of “best guess” structural parameters supplied by the user. Extrema bound constraints are implemented by means of a sinusoidal parameter transform. Ultimately, the code is to be compiled and made available to users via the ISIS Pulsed Neutron Facility, UK.

Item Type: Thesis (Doctor of Philosophy (PhD))
Subjects: Q Science > QC Physics
Divisions: Faculties > Sciences > School of Physical Sciences
Depositing User: Suzanne Duffy
Date Deposited: 18 Mar 2014 14:38 UTC
Last Modified: 29 May 2019 12:00 UTC
Resource URI: https://kar.kent.ac.uk/id/eprint/38807 (The current URI for this page, for reference purposes)
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