Dr Gavin Mountjoy is a Reader in Condensed Matter Physics at the University of Kent. During his research career he has worked at the Cavendish Laboratory, University of Cambridge, the Center for Solid State Science, Arizona State University, and the Functional Materials Group, University of Cagliari. Gavin is a long-standing member of the School of Physical Sciences, University of Kent. His research involves structural characterization techniques of electron microscopy, x-ray spectroscopy, x-ray and neutron diffraction, and molecular dynamics modelling. He is primarily interested in applying these techniques to nanocomposites and amorphous solids, especially oxide glasses, with applications in optics, as energy materials, or as biomaterials.
Short range order in fluorine containing CaO-SiO2-CaF2 glasses from NMR, neutron diffraction, and x-ray absorption spectroscopy
Laura A. Swansbury1,2 & Gavin Mountjoy1*
1School of Physical Sciences, University of Kent, Canterbury, Kent CT2 7NH, UK
2Morgan Advanced Materials, Tebay Road, Bromborough, Wirral, CH62 3PH, UK
The glass system CaO-SiO2-CaF2 has been studied to help elucidate the structure of more complex CaO-SiO2-P2O5-CaF2 fluorine-containing bioactive glasses. The CaO-SiO2-CaF2 glass series was synthesized and the glass transition temperature declined linearly with increasing CaF2 concentrations. Compositional analysis revealed that fluorine losses occurred due to fluorine volatilisation. The chemical shift positions in the 19F MAS-NMR spectra became more negative with increasing CaF2 concentrations, becoming more similar to that of pure CaF2. By studying the calcium environment using neutron diffraction and x-ray absorption spectroscopy at the Ca K-edge, reasonably consistent values for Ca-F and Ca-O nearest neighbour distances of approximately 2.3Å and 2.4Å (respectively) could be obtained. However, it was challenging to establish the coordination numbers and disorder in distances of nearest neighbours.