Two-dimensionsal Glasses


The structure of glass has been the subject of many studies, however some details remained to be resolved. With the advancement of microscopic imaging techniques and the successful synthesis of two-dimensional materials, images of two-dimensional glasses (bilayers of silica) are now available, confirming that this glass structure closely follows the continuous random network model. These images provide complete inplane structural information such as ring correlations, and intermediate range order and with computer refinement contain indirect information such as angular distributions, and tilting. This dissertation reports the first work that integrates the actual atomic coordinates obtained from such images with structural refinement to enhance the extracted information from the experimental data. The correlations in the ring structure of silica bilayers are studied and it is shown that short-range and intermediate-range order exist in such networks. Special boundary conditions for finite experimental samples are designed so atoms in the bulk sense they are part of an infinite network. It is shown that bilayers consist of two identical layers separated by a symmetry plane and the tilted tetrahedra, two examples of added value through the structural refinement. Finally, the low-temperature properties of glasses in two dimensions are studied. This dissertation presents a new approach to find possible two-level systems in silica bilayers employing the tools of rigidity theory in isostatic systems

Arizona State University