POWRE: Relaxation Study of a Trigonal Network Glass

This project is a molecular dynamics simulation study of the structure and relaxation of vitreous boron oxide, which belongs to the general class of network glasses, and specifically consists of trigonally coordinated boron atoms. The long term goal of the research is to establish a relation between short range order (dimensionality or coordination) of network glasses and physical properties relevant to the glass transition. The basis of the proposal is the relaxation behavior of a material with three-fold coordination. A rapid decrease in relaxation rates and the onset of com-plex dynamics such as non-exponential relaxation is one of the universal signatures of entrance to the glassy state. Materials with four-fold (silica glass) and two-fold (linear polymers) coordi-nation have been more extensively studied than three-fold coordinated materials such as B2O3. The intermediate range order of B2O3 is also of interest. Experiments have revealed the existence of six member boroxol rings, but confirmation with simulation studies has met only limited suc-cess. The work will proceed in two phases: characterizing the structure of B2O3 and studying re-laxation. A promising model that includes many body polarization effects is being adapted to study B2O3 since the polarization effects it describes have been shown necessary for a realistic model of boron oxide. This model will be used to investigate the structure of boron oxide, spe-cifically the question of boroxol rings. Full characterization of the relaxation of B2O3 will follow.

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This is a research enhancement grant made under the Professional Opportunities for Women in Research and Education (POWRE) program. The exploratory research activity proposed defines a new area of interest for the PI. The project will allow the PI to apply her expertise in the area of molecular simulation to problems in glass science. The research is expected to contribute basic materials science knowledge at a fundamental level of special relevance to the behavior of glassy materials. The project is co-supported by the Division of Materials Research, and the MPS OMA(Office of Multidisciplinary Activities).

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