SusChEM: Collaborative Research: experimental and computational study of structure and thermodynamics of rare earth oxides above 2000 C

SusChEM：合作研究：2000℃以上稀土氧化物结构和热力学的实验和计算研究

• 批准号: 1506229
• 负责人: Alexandra Navrotsky
• 金额: $ 40.28万
• 依托单位: University of California-Davis
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-07-01 至 2018-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1506229&HistoricalAwards=false
• 关键词: SusChEM; Collaborative; Research; experimental; computational

NON-TECHNICAL SUMMARY: Materials which are stable to very high temperatures are needed for applications in aerospace, energy, and other technologies. Many such materials contain rare earth oxides, critical materials in potential short supply. Novel experimental and computational methods are studying the structure and stability of such rare earth oxides. The methodology includes diffraction (determination of crystal structure) and calorimetry (measurement of heat effects associated with melting and other reactions) on laser heated samples levitated in a gas stream and not contaminated by contact with other materials, as well as theoretical calculations. Such studies offer a unique opportunity to obtain fundamental understanding of structures, phase transitions, and melting properties and applications to technological problems. The project will also advance general experimental and computational techniques for high temperature research. It will offer opportunities for both undergraduates and graduate students in materials science, chemistry, physics, and engineering to take part in state-of-the-art research in both university and national laboratory settings. Rare earth oxides are "critical materials" in the sense of being technologically indispensable, but with limited supply. Developing energy-efficient, and environmentally-friendly processes "from cradle to grave" or, better still "from cradle to cradle" (involving recycling) is essential to sustainable management of resources and technology. TECHNICAL DETAILS: Rare earth oxides are critical materials essential to many important technologies yet their high temperature properties, needed for such applications, are poorly known. Their structure and thermodynamics above 2000°C are being studied using a combination of novel experimental and computational methods. Aerodynamic levitation and laser heating are being used for in situ X-ray diffraction at the Advanced Photon Source, in situ neutron diffraction at the Spallation Neutron Source and for drop calorimetry at the UC Davis Peter A. Rock Thermochemistry Laboratory. Enthalpies of solid state phase transitions and fusion are being measured by calorimetry, and volume changes on phase transitions and thermal expansion of high temperature phases are being determined by diffraction. High temperature thermal analysis complements drop calorimetry. Fusion enthalpies are required for reliable calculations of eutectics of multi-component systems containing rare earths. Ab initio computations of high temperature heat capacities, thermal expansion, and temperatures and enthalpies of phase transitions and fusion are being performed at Brown University using post-density functional theory (DFT) methods, such as hybrid functionals and DFT+U, in conjunction with statistical mechanics techniques such as cluster expansion, lattice dynamics analysis and molecular dynamics. Computed thermal expansion and enthalpies of phase transitions and fusion are being compared to experimental measurements and calculations are being extended to high temperature properties of rare earth oxides not yet accessible experimentally. Thermodynamics are central to optimizing the processes for the rare earth oxides; as such this project contributes to sustainability.

非技术摘要：在航空航天，能源和其他技术中应用需要稳定在非常高温下的材料。许多这样的材料含有稀土氧化物，潜在短供应中的关键材料。新颖的实验和计算方法正在研究这种稀土氧化物的结构和稳定性。该方法包括衍射（确定晶体结构）和量热法（测量与熔融和其他反应相关的热效应）对在气流中悬浮的激光加热样品上的衍射（测量与熔融和其他反应相关的热效应），而不会因与其他材料的接触以及理论计算而受到污染。这些研究提供了一个独特的机会，可以获得对结构，相位过渡以及对技术问题的融化属性以及应用的基本了解。该项目还将推进高温研究的一般实验和计算技术。它将为本科生和研究生提供材料科学，化学，物理和工程学的研究生，以参与大学和国家实验室环境的最先进研究。从技术上必不可少的意义上讲，稀土氧化物是“关键材料”，但供应有限。从摇篮到坟墓“从摇篮到摇篮到摇篮”（涉及回收），开发节能效率和环境友好的过程对于资源和技术的可持续管理至关重要。技术细节：稀土氧化物是许多重要技术至关重要的材料，但其高温特性（此类应用所需的高温特性）却鲜为人知。他们的结构和热力学高于2000°C，正在使用新型实验和计算方法的组合进行研究。空气动力学悬浮和激光加热用于在晚期光子源处进行原位X射线衍射，散布中子中子源的原位中子衍射，以及在UC Davis Peter A.岩石A.岩石热化学实验室的下降热量法。通过量热法测量了固态相变和融合的焓，相变的体积变化和高温相的热膨胀正在通过衍射确定。高温热分析完整降低量热法。融合焓是对包含稀土的多组分系统的共晶的可靠计算所必需的。通过使用后密度功能理论（DFT）方法进行高温热容量，热热容量，热量膨胀以及相转换和融合的温度以及焓的计算，例如混合功能和DFT+U，以及与统计力学技术（例如群集扩张，Lattice Dynamiltion and Lattice Dynamilticals and Inalcular Dynamelicts and contection and Hybrid功能和DFT+U）进行。将计算的热膨胀和相变和融合的焓与实验测量进行了比较，并且计算已扩展到稀有氧化物的高温特性，尚未实验。热力学对于优化稀土氧化物的过程至关重要。因此，这个项目有助于可持续性。

项目成果

New Developments in the Calorimetry of High-Temperature Materials

• DOI: 10.1016/j.eng.2019.03.003
• 发表时间: 2019-07
• 期刊: Engineering
• 影响因子: 12.8
• 作者: A. Navrotsky