POWRE: Relaxation Study of a Trigonal Network Glass

本项目是对玻璃态氧化硼的结构和弛豫的分子动力学模拟研究，它属于网络玻璃的一般类别，具体由三配位的硼原子组成。该研究的长期目标是建立网络玻璃的短程有序性(维度或配位)与与玻璃化转变相关的物理性质之间的关系。该建议的基础是具有三重配位的材料的松弛行为。弛豫速率的迅速下降和复杂动力学的开始，如非指数弛豫，是进入玻璃态的普遍标志之一。具有四重配位(石英玻璃)和两重配位(线性聚合物)配位的材料比具有三重配位的材料(如B2O)得到了更广泛的研究。B_2O_3的中程有序也令人感兴趣。实验揭示了六元硼氧环的存在，但用模拟研究证实的结果是有限的。这项工作将分两个阶段进行：表征B_2O_3的结构和研究再松弛。一个有希望的模型，包括许多身体极化效应，正在被用来研究B2O3，因为它所描述的极化效应已经被证明是现实的氧化硼模型所必需的。这个模型将被用来研究氧化硼的结构，特别是研究硼氧环的问题。接下来将对B2O3的松弛进行全面的表征。%这是根据妇女在研究和教育中的职业机会(POWRE)计划提供的研究增强补助金。拟议的探索性研究活动为和平研究所确定了一个新的感兴趣的领域。该项目将允许PI将她在分子模拟领域的专业知识应用于玻璃科学中的问题。这项研究有望在与玻璃材料的行为特别相关的基础水平上贡献基本的材料科学知识。该项目由材料研究司和MPS OMA(多学科活动办公室)共同支持。***

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. %%% 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). ***