Glass under pressure: its structure and related properties

High pressures have a significant impact on the structure-related properties of glass and are encountered in scenarios ranging from fracture mechanics, where stresses in the gigapascal regime are easily generated by sharp-contact loading, to the manufacture of permanently densified materials with tuned physical characteristics. It is therefore important to understand the mechanisms of compaction, which can occur gradually when load is applied, or abruptly as in so-called polyamorphic transformations. Unravelling the nature of structural change is a formidable task because of the complexity that originates from the atomic-scale disorder of glass and the experimental difficulties that are associated with the in situ investigation of materials under extreme conditions. It is therefore necessary to combine the results obtained from a wide variety of experiments with modern modelling methods in order to reveal the structure and related properties of glass under load.

In this project, focus will be on the development of in situ high-pressure Raman spectroscopy to probe the structure and dynamics of materials. The work will involve the implementation of diamond anvil cell (DAC) techniques to access pressures up to 50 GPa, which are readily encountered in the compaction of glass under a sharp indenter. The response of these materials under load is important for understanding the birth of strength limiting flaws that lead to crack-propagation and failure of e.g. the display glass used in hand-held electronic devices. The results will complement those obtained from neutron and x-ray scattering investigations to build a complete experimental picture of the changes that occur in glass under pressure. The results will also be used to test the efficacy of the interaction models used in molecular dynamics simulations of these materials. In turn, once a realistic model has been established, the molecular dynamics simulations will provide more detailed information on the mechanisms of structural collapse and their effect on material properties such as the compressibility and elastic constants.

The glassy materials will be based on those from the CaO-MgO-Al2O3-SiO2 (CMAS) system. This choice is motivated by the importance of this system in industry for making display glass for use, e.g., in mobile electronic devices, and for providing the substrate for catalytic converters. CMAS is also a model system in geophysics for dry basaltic melts, where the glass is often used as a proxy for the liquid phase in order to avoid experimental difficulties at high-temperatures. Thus, the results from the project will have both scientific and technological impact.

Corning Inc., a world-leading manufacturer of specialty glass and ceramic materials, have a keen interest in the project and will provide samples, sample characterisation and technical advice.

Applicants should have a background in the physical sciences and have or expect to gain a First or Upper Second Class UK Honours degree, or the equivalent from an overseas University.

Informal enquiries should be directed to Dr Anita Zeidler ([Email Address Removed]).

Formal applications should be made via the University of Bath’s online application form for a PhD in Physics:
https://www.bath.ac.uk/samis/urd/sits.urd/run/siw_ipp_lgn.login?process=siw_ipp_app&code1=RDUPH-FP01&code2=0012

More information about applying for a PhD at Bath may be found here:
http://www.bath.ac.uk/guides/how-to-apply-for-doctoral-study/

Anticipated start date: 1 October 2018