1. Sudden structural transformation in glass NSF Award Number: 0603933 Intermediate-range structure and dynamics in complex Ge-As-chalcogenide glasses and liquids NSF Award Number: 0603933 Award title: Intermediate-range structure and dynamics in complex Ge-As-chalcogenide glasses and liquids PI name: Sabyasachi Sen Instituiton name: University of California-Davis

2. Sudden structural transformation in glass NSF Award Number: 0603933 Intermediate-range structure and dynamics in complex Ge-As- chalcogenide glasses and liquids Properties of non-oxide glasses in the Ge-As-S/Se/Te systems that are currently being developed for applications in the areas of photonics and telecommunication are strongly dependent on their structure at the length scale of several inter-atomic distances. Professor Sabyasachi Sen’s group is developing experimental and simulation techniques to develop fundamental understanding of the structure-property relationships and the effects of pressure and temperature on the atomic structure of these disordered materials, which is crucial for controlling their properties. One important recent finding concerns the experimental observation of a sudden structural transformation in some of these glasses as a function of pressure. The Sen group has shown that upon squeezing to high pressures, certain non-oxide glasses with a molecular structure suddenly transforms into a high-density network structure with the same chemical composition but very different physical properties. This research may identify novel ways of making glassy materials with unusual properties. Moreover, these findings will play a key role in addressing a fundamental and currently highly debated issue in materials physics - which is whether, similar to crystalline materials, structurally and thermodynamically distinct phases of the same composition exist also in the case of glasses and liquids.

3. Sudden structural transformation in glass NSF Award Number: 0603933 Intermediate-range structure and dynamics in complex Ge-As-chalcogenide glasses and liquids A schematic graphical representation of the pressure induced structural transformation seen in an arsenic sulfide glass. The low-density molecular structure is shown on the left and the high-density network structure on the right (large and small circles represent arsenic and sulfur atoms, respectively).