The Intermediate Phase in Network Glasses

网络眼镜的中间阶段

• 批准号: 0101808
• 负责人: Punit Boolchand
• 金额: $ 33万
• 依托单位: University of Cincinnati Main Campus
• 依托单位国家: 美国
• 项目类别: Continuing grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-04-01 至 2005-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0101808&HistoricalAwards=false
• 关键词: Intermediate; Phase; Network; Glasses

This project concerns the properties of glasses and their phase transformations. The physical nature of the Intermediate phase (IP) that separates the Floppy phase (FP) from the Rigid Phase (RP) in select chalcogenide glass systems will be examined. These properties will be investigated in four different sets of experiments. First, temperature-dependent Raman scattering studies of Ge-Se, As-Se and Ge-As-Se bearing bulk glasses will be performed over the range from 78K to Tg+200 K to examine the nature of molecular structure changes taking place across Tg in the FP, IP and the RP. Second, the same glass systems, but now synthesized as obliquely deposited thin-films (obliqueness angle in the range from 0 to 80 degrees) will be examined in their virgin and photo-illuminated state in Raman, 119Sn Mossbauer effect and photo-contraction studies. The columns formed in the porous (obliquely) deposited films may represent the elements of medium range structure responsible for the rather unique physical properties of glasses in the IP. Third, pnictide based glass systems, such as As-Se, As-S and As-Ge-Se bearing glasses will be examined in Raman, NQR, EXAFS and 129I Mossbauer spectroscopic studies to elucidate new aspects of molecular structure recently inferred from the discovery of the IP in Modulated Differential Scanning Calorimetry (MDSC) measurements. Lastly, 119Sn Lamb-Mossbauer factors in select glasses will be established as a function of mean coordination number to contrast the local elastic response of glasses in the IP from those in the FP and the RP. Students will participate in this research and will thereby be prepared to enter the scientific technical work force of the 21st Century.This research concerns the properties of glasses and glass systems. Glasses are characterized by progressive cross-linking of a floppy network that will render it rigid at a critical connectivity. This is often realized by systematically changing the chemical composition in a glass system. Experiments on sulfur- and selenium-bearing glasses have shown however that a floppy phase (FP) and a rigid phase (RP) are separated by an intermediate phase (IP). Four different sets of experiments will be performed to establish the physical nature of the IP in select glass systems. Different experimental techniques will be brought to bear on selected glass systems over a range of glass compositions that encompass the three different phases. The experiments will be performed over a wide temperature range that embraces the transitions among the phases. Furthermore, specially fabricated thin films of these glasses will be investigated. These experiments are expected to shed light on the intricacies of glass systems under various conditions of temperature and composition and the results will be of use for the incorporation of new glasses in advanced technological devices. Students will participate in these investigations. They will thereby acquire training in one of the important contemporary areas of condensed matter physics and materials science and will be prepared to enter the scientific/ technical work force in industry, academe, and the government.

该项目涉及眼镜的特性及其相变。将检查将软质相（FP）与精选硫代基因玻璃系统中刚性相（RP）分开的中间相（IP）的物理性质。这些特性将在四个不同的实验集中研究。首先，将在从78K到TG+200 K的范围内进行GE-SE，AS-SE和GE-AS-SE轴承大量玻璃的温度依赖性拉曼散射研究，以检查FP，IP和RP中TG发生的分子结构变化的性质。其次，相同的玻璃系统，但现在合成为倾斜沉积的薄膜（在0到80度范围内的倾斜角度），将在其处女和光鲜的Raman，119SN Mossbauer效应和照片征收研究中进行检查。在多孔（倾斜）沉积膜中形成的色谱柱可能代表了IP中玻璃杯中相当独特的物理特性的中等范围结构的要素。第三，将在拉曼，NQR，EXAFS和129i Mossbauer光谱研究中检查基于PNICTIDE的玻璃系统，例如AS-SE，AS-S和AS-GE-SE轴承玻璃，以阐明最近从模拟的不同扫描扫描量表中发现IP的分子结构的新方面。最后，将确定精选眼镜中的119SN羔羊 - 摩斯鲍尔因子是平均配位数的函数，以对比IP中FP和RP中的IP玻璃的局部弹性响应。学生将参与这项研究，因此将准备进入21世纪的科学技术劳动力。这项研究涉及眼镜和玻璃系统的特性。玻璃的特征是软盘网络的进行性交联，该网络将使其在关键的连通性处刚化。通常通过系统地改变玻璃系统中的化学成分来实现这一点。然而，对硫和硒玻璃的实验表明，软盘相（FP）和刚性相（RP）通过中间相（IP）分离。将执行四组不同的实验集，以确定精选玻璃系统中IP的物理性质。在涵盖三个不同阶段的一系列玻璃组合物上，将在选定的玻璃系统上携带不同的实验技术。 实验将在宽的温度范围内进行，该温度范围内包含相位之间的过渡。此外，将研究这些眼镜的特别制造的薄膜。 预计这些实验会在各种温度和成分条件下阐明玻璃系统的复杂性，结果将用于将新玻璃掺入高级技术设备中。 学生将参加这些调查。 他们将在当代重要的物理和材料科学的当代重要领域之一中获得培训，并准备进入工业，学术界和政府的科学/技术劳动力。