PhD position: Role of structure in glass formation and mechanical properties

In condensed matter physics, the structure of a material is integral to its nature. Glasses are not an easy fit in this model. At a fundamental level, it is not known how their structure reflects their formation or the properties they subsequently display. For crystals, it is straight-forward: at the liquid-to-crystal phase transition, symmetry is broken and translational symmetry arises. The new phase is rigid and this property is determined by the broken symmetry of the structure. The force exerted on any particle in the array is cancelled by neighbours. When the cohesive lattice force is overcome, the crystal deforms via the creation and propagation of lattice defects.

Glasses thwart this description; they are solids with liquid structure. The nature of the “glass transition” and why some materials form glasses more easily than others are deep mysteries that frustrate physicists. The atomic-scale structures that allow glasses to deform and are responsible for their Achilles’ heel of shear banding and brittle failure are not known. Empirical progress on this front is stymied by the lack of a routine method for characterising disordered structures. The lack of knowledge and understanding of the structure of glasses is a major road-block for glass science and technology.

A series of new and measureable structural parameters for glasses has recently been demonstrated by Monash University researchers [1,2,3]. This project will further test these new parameters on a series of metallic and silicate glasses to determine what role, if any, structure plays in properties such as glass-forming ability and mechanical response. The project will involve electron diffraction measurements on a next-generation scanning- transmission electron microscope with a low-noise, fast read-out rate direct electron detector (UltraTEM – installation in the Monash Centre for Electron Microscopy scheduled for late 2019). There will be opportunities for interactions with Prof. Kiyonori Suzuki (Materials Science and Engineering, Monash University), Dr Daniel East (CSIRO, Lab22) and collaborators at the University of Adelaide and Ames Laboratory, Iowa.

The project would suit a student interested in experimental materials physics and developing new data analysis tools.

References

[1] A. C. Y. Liu, M. J. Neish, G. Stokol, G. A. Buckley, L. A. Smillie, M. D. de Jonge, R. T. Ott, M. J. Kramer, and L. Bourgeois, Phys. Rev. Lett. 110, 205505, (2013)

[2] A. C. Y. Liu, R. F. Tabor, L. Bourgeois, M. D. de Jonge, S. T. Mudie, and T. C. Petersen, Phys. Rev. Lett., 116, 205501 (2016)

[3] A. C. Y. Liu, R. F. Tabor, M. D. de Jonge, S. T. Mudie, and T. C. Petersen, Proc. Nat. Acad. Sci., 114, 10344–10349, (2017)