Self-Organization in Network Glasses-Beyond Selenides

共价网络玻璃通常由IV族和/或V族硒化物组成，并且存在三种基本类型的弹性相-柔性相、中间相和应力刚性相。柔性相由弱交联结构组成，并具有“松弛”模式，而应力刚性相由具有应力产生“冗余”键的严重交联结构组成。中间相（IP）是最佳交联结构，其是略微刚性但无应力的特征，其导致不可预见的功能性，例如玻璃化转变的热可逆性、不存在老化、液体状构型熵和网络适应性，以排出应力并降低其自由能。该个人研究者奖支持一个项目，将IP的研究从硒化物扩展到硫化物和氧化物。将进行调制DSC、拉曼、IR反射率和摩尔体积测量作为玻璃组成的函数，以建立IP。这些测量将允许阐明的作用，化学键合和结构上的IP键合的分数离子性增加。可能的应用包括优化三端器件、平板显示器、可编程单元金属化存储器器件、蛋白质折叠和药物设计中的薄膜栅极布线。对非晶半导体和绝缘体的研究已被证明是一个优秀的培训基地，为年轻的物理学家和电气工程师寻找工作，在工业界和学术界。非技术abstractAdvances in synthesis，纯化的起始材料和详细的成分研究已经导致认识到，非晶半导体的物理性质，包括玻璃可以突然改变化学组成。这些发展已经允许探测网络玻璃中的刚性转变（柔性和中间相玻璃之间）和应力转变（中间相和应力刚性相之间）。这个个人研究者奖支持一个项目，以调查中间相（IP）在选择硫化物和氧化物，扩展目前的结果，IP从硒化物系统，更离子。将进行热、光学、机械和电气测量，以确定IP及其老化行为。该项目的目标是建立这些技术上重要的材料的IP，并从玻璃子结构的角度了解它们。这些发现也将作为这些阶段的数值模拟的界限，使用目前正在美国和欧洲进行的第一原理方法。 学生将接受最先进的技术和半导体材料生长的培训，这将为美国的科学和工程基础设施提供就业机会。

Technical abstractCovalent network glasses are usually composed of the group IV and/or V selenides, and exist in three basic types of elastic phases- flexible, intermediate and stressed-rigid. Flexible phases are made up of weakly cross-linked structures and possess "floppy" modes, while stressed-rigid phases consist of heavily cross-linked structures that have stress creating "redundant" bonds. Intermediate phases (IPs) are optimally cross-linked structures that are marginally rigid but stress-free features that lead to unforeseen functionalities, such as thermal reversibility of the glass transition, absence of aging, liquid-like configurational entropies, and network adaptability to expel stress and lower their free energies. This individual investigator award supports a project to extend investigations of IPs from selenides to sulfides and oxides. Modulated DSC, Raman, IR reflectance and Molar volume measurements will be undertaken as a function of glass composition to establish IPs. These measurements will permit elucidating the role of chemical bonding and structure on IPs as fractional ionicity of bonding increases. Possible applications include optimization of thin-film gate dielectrics in 3-terminal devices, flat panel displays, programmable cell metallization memory devices, protein folding and drug design. Research on amorphous semiconductors and insulators has proven to be an outstanding training ground for young physicists and electrical engineers seeking jobs in industry and academia.Non-Technical abstractAdvances in synthesis, purification of starting materials and detailed compositional studies have led to the recognition that physical properties of amorphous semiconductors including glasses can change abruptly with chemical composition. These developments have permitted probing the rigidity transition (between flexible and intermediate phase glasses) and the stress transition (between intermediate and stressed-rigid phases) in network glasses. This individual investigator award supports a project to investigate Intermediate phases (IPs) in select sulfides and oxides, extending present results of IPs from selenides to systems that are more ionic. Thermal, optical, mechanical and electrical measurements will be undertaken to establish IPs and their aging behavior. The goal of the project is to establish IPs of these technologically important materials and to understand them in terms of glass sub-structure. These findings will also serve as bounds for numerical simulations of these phases using first principles methods that are currently ongoing in the US and Europe. Students will be trained in state-of the art techniques and semiconducting materials growth, which will open jobs in Science and Engineering infrastructure of the US.