RUI: Complex Dynamics in Glass-forming Oxide Melts

RUI：玻璃形成氧化物熔体的复杂动力学

基本信息

批准号：
2051396
负责人：
David Sidebottom
金额：
$ 30万
依托单位：
Creighton University
依托单位国家：
美国
项目类别：
Continuing Grant
财政年份：
2021
资助国家：
美国
起止时间：
2021-06-01 至 2025-05-31
项目状态：
未结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=2051396&HistoricalAwards=false
关键词：
RUI Complex Dynamics Glass forming

项目摘要

NON-TECHNICAL DESCRIPTION: Oxide glasses feature prominently in important commercial applications ranging from high-speed optical fiber communications to shock-resistant touchscreens found in a myriad of smart devices. Development of these materials is informed by their unique "ball and stick" atomic structure, wherein atoms (balls) are interconnected by covalent bonds (sticks) to produce a continuous network where bond density largely determines the response (rigid or flexible) of the material to applied shear forces. However, several recent observations are inconsistent with this simple model and appear to be better explained by appealing to an alternative network of "weakest linkages" obtained when certain redundant connections are omitted. The project seeks to attain deeper understanding of how atomic-level glass structure ultimately determines material properties by generating much needed new observations of the glassy dynamics that can definitively test model predictions. Work is performed primarily by undergraduate students who gain valuable research skills as part of their trajectory toward advanced studies. The project also offers non-science students a peek at the excitement of science and engineering research through the creation and delivery of a new hands-on materials science course that incorporates service-learning activities in the surrounding K-12 community.TECHNICAL DETAILS: The properties of oxide glasses vary from floppy to rigid depending on the degree to which mechanical constraints imposed by a network of covalent bonds percolate within the structure. Properties also include the complex dynamics (both non-Arrhenius rates and non-exponential decay) of the viscoelastic relaxation of melt which has rarely been studied in network-forming oxides. Recently, two competing models propose differing ways in which thermodynamics might be integrated with static bond constraints to predict viscoelastic properties like the glass transition temperature and fragility. One assumes atomic constraints with an hierarchy of thermal strengths while the other emphasizes a mean field structure obtained by coarse-graining over certain pockets of rigid matter. Here, dynamic light scattering (together with high-resolution Raman spectroscopy) is performed on a selection of oxide systems to provide a critical test of the two models while also providing much needed characterization of the relaxation in these refractory melts. These studies, conducted primarily by undergraduate students, provide hands-on experience with multiple forms of spectroscopy and serve to train the next generation of science practitioners.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

非技术描述：氧化物眼镜在重要的商业应用中具有突出的特征，从高速光纤通信到无数智能设备中的防震触摸屏。这些材料的开发是通过其独特的“球和棍子”原子结构所告知的，其中原子（球）通过共价键（棒）互连，以产生连续的网络，在该网络中，键密度在很大程度上决定了材料的响应（刚性或灵活）以施加的剪切力。但是，最近的几个观察结果与这个简单的模型不一致，并且通过忽略某些冗余连接时获得的替代网络的“最弱点”网络可以更好地解释。该项目试图通过产生急需的玻璃动力学新观察结果来更深入地了解原子级玻璃结构如何最终确定材料特性，以确定测试模型预测。工作主要是由本科生进行的，他们在高级研究方面获得了宝贵的研究技能。 The project also offers non-science students a peek at the excitement of science and engineering research through the creation and delivery of a new hands-on materials science course that incorporates service-learning activities in the surrounding K-12 community.TECHNICAL DETAILS: The properties of oxide glasses vary from floppy to rigid depending on the degree to which mechanical constraints imposed by a network of covalent bonds percolate within the structure. 性质还包括熔融粘弹性弛豫的复杂动力学（非阿拉尼乌斯速率和非指数衰变），这些融化液在网络形成的氧化物中很少研究。最近，两个竞争模型提出了可以与静态键约束集成的不同方式，以预测玻璃过渡温度和脆弱性等粘弹性。一个假定具有热强度层次结构的原子约束，而另一个则强调了通过在某些刚性物质上进行的粗粒度获得的平均场结构。在这里，在选择氧化物系统上进行了动态光散射（以及高分辨率的拉曼光谱），以提供对这两种模型的批判性测试，同时还提供了这些难治性熔体中宽松的急需表征。这些研究主要由本科生进行的研究提供了多种形式的动手经验，并有助于培训下一代科学从业人员。该奖项反映了NSF的法定任务，并认为值得通过基金会的知识分子优点和更广泛的影响审查标准通过评估来进行评估。