Self-Organization in Network Glasses

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Controlled laboratory experiments on network glasses have recently permitted decoding the physical principles that underlie self-organization of disordered systems. Of particular interest, is the discovery of an "intermediate phase", which is bounded by the rigidity and stress transitions. This phase displays most unusual physical behavior including glass transitions (Tg) that are almost completely thermally reversing in character and not aging with time at T Tg. This award will focus on sulfide- and oxide-glasses, in which the nature of the intermediate phases will be explored using Raman scattering and modulated Differential Scanning Calorimetric experiments. These glasses are widely used in photonic and electronic applications, and the discovery of such phases in these systems will impact information storage and memory applications. Graduate, undergraduate, and high school students will participate in this project, receiving training in this field and also sharing in the excitement of discoveries of new glassy phases. An exchange of ideas and knowledge among the participants and colleagues at other US universities and abroad will be continue to strengthen the research. Certain liquids upon cooling form disordered solids that consist of networks of specific building blocks like tetrahedra or pyramids. These solids are called network glasses and silica is a familiar example. Under specific conditions network glasses can self-organize to display intriguing physical properties such as thermally reversing glass transitions and absence of time evolution in structure at temperatures below the glass transition temperature. The atomic structural arrangements that lead to self-organization of disordered networks are of scientific interest, and will be examined using sophisticated light scattering and thermal probes. This project will focus on sulfide- and oxide-glasses, in which novel glassy phases are expected. These materials are most widely used in photonic and electronic applications, and the discovery of such phases in these systems could have profound consequences on their applications. Two full time graduate students including a female student, two part-time undergraduate students, and two high-school students working in summer recess will be involved in the scientific discovery phase of this work.