POWRE: Relaxation Study of a Trigonal Network Glass

本课题是对玻璃体氧化硼的结构和弛豫的分子动力学模拟研究。玻璃体氧化硼属于一般类型的网状玻璃，具体由三角配位硼原子组成。研究的长期目标是建立网络玻璃的短程有序（维数或配位）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。弛豫速率的快速下降和非指数弛豫等复杂动力学的开始是进入玻璃态的普遍特征之一。具有四重配位（硅玻璃）和两重配位（线性聚合物）的材料比三重配位材料（如B2O3）得到了更广泛的研究。B2O3的中间阶序也是我们感兴趣的。实验已经揭示了六元博罗索环的存在，但模拟研究的证实只取得了有限的成功。这项工作将分两个阶段进行：表征B2O3的结构和研究弛豫。一个包含许多体极化效应的有前途的模型正被用于研究B2O3，因为它所描述的极化效应已被证明是一个现实的氧化硼模型所必需的。该模型将用于研究氧化硼的结构，特别是硼酚环的问题。接下来将详细描述B2O3的弛豫特性。这是在研究和教育领域妇女专业机会（POWRE）计划下提供的一项研究加强补助金。提出的探索性研究活动为PI定义了一个感兴趣的新领域。该项目将允许PI运用她在分子模拟领域的专业知识来解决玻璃科学中的问题。该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础材料科学知识。该项目由材料研究部和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). ***