Structure of supercooled liquid and glassy germania and the thermal expansion of the Ge–O bond

We propose to measure the structure of GeO2 glass and supercooled liquid as a function of temperature. These measurements will provide the thermal expansion coefficient of the Ge–O bond, and allow for separating the vibrational and configurational components of Ge–O bond length changes in multicomponent germanate melts. This is important for accurately tracking temperature dependent changes in Ge–O coordination number, which often exceeds the tetrahedral value of four in multicomponent germanates. Furthermore, the proposed measurements will be sensitive to any coordination changes occurring in liquid GeO2, providing a verification, or otherwise, of purported 3-fold coordinated Ge which has been suggested to exist based on Raman spectroscopic observations.
This proposal will support another one aimed at temperature dependent structure measurements in the glassy, supercooled liquid and molten states, for a small number of Ba borogermanate compositions. All three proposals will form part of the PhD thesis work of Reuben Tosh, a recently successful applicant to the ISIS Facility Development studentship jointly funded by ISIS and University of Nottingham, with Dr. Oliver Alderman and Dr. Emma Barney as respective supervisors.