Abstract

The study of amorphous materials remains an area of interest across many scientific disciplines. eg., materials science, Earth science (other than Canada), condensed matter physics, biophysics. Relatively recently it has been found that amorphous materials may undergo polyamorphic phase transitions or polyamorphism. The term polyamorphism describes the existence, in an amorphous system of fixed composition, of two or more structurally distinct phases, the transition between which occurs across a defined interface. The concept of polyamorphism has major implications for understanding the behaviour of liquids and melts. One system that appears to exhibit such behaviour is the GeO₂-SiO₂ system.

Recently, we carried out a series of in-situ experiments at high temperatures, high pressures and both high temperature and pressure, to explore the possible polyamorphic characteristics of this system. The experiments were performed on the ODE beamline at Soleil (high T Ge K-edge EXAFS), and the BM29 (High T and P Ge K-edge EXAFS) and ID16 (High P RIXS) beamlines at the ESRF. I shall (hopefully) present some preliminary results from these studies, as well as, the results of some recent work on other amorphous systems such as borosilicate glasses. These latter glasses are used as a model system for the complex glass (R7T7) used in the encapsulation and storage of high level radioactive waste.

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