Self-Organization in Network Glasses-Beyond Selenides

技术摘要共价网状玻璃通常由IV族和/或V族硒化物组成，存在弹性相的三种基本类型：柔性相、中间相和应力刚性相。柔性相由弱交联结构组成，具有“软盘”模式，而应力刚性相由强交联结构组成，具有应力产生“冗余”键。中间相（ip）是一种最佳交联结构，具有微刚性，但无应力特征，可导致不可预见的功能，如玻璃化转变的热可逆性，不老化，类液体构型熵，以及排除应力和降低自由能的网络适应性。这项个人研究者奖支持一个项目，将对硒化物的研究扩展到硫化物和氧化物。调制DSC，拉曼，红外反射率和摩尔体积测量将作为玻璃成分的函数来建立IPs。这些测量将允许阐明化学键和结构的作用，随着键的分数离子度的增加。可能的应用包括优化3端器件中的薄膜栅极电介质、平板显示器、可编程细胞金属化存储器件、蛋白质折叠和药物设计。非晶半导体和绝缘体的研究已被证明是年轻物理学家和电气工程师在工业界和学术界寻找工作的一个杰出的培训基地。摘要在合成、原料纯化和详细成分研究方面的进展使人们认识到非晶半导体（包括玻璃）的物理性质会随着化学成分的变化而突然改变。这些发展已经允许探测网络玻璃中的刚性转变（在柔性相和中间相之间）和应力转变（在中间相和应力刚性相之间）。该个人研究者奖支持一个研究选定硫化物和氧化物的中间相（ipps）的项目，将目前的ipps结果从硒化物扩展到更多离子的系统。将进行热、光学、机械和电学测量，以确定IPs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知识产权，并从玻璃子结构的角度来理解它们。这些发现也将作为目前正在美国和欧洲进行的使用第一性原理方法对这些阶段进行数值模拟的界限。学生将接受最先进的技术和半导体材料增长方面的培训，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.