FRG: Unit Defect and Microstructural Processes at Metal/Dielectric Interfaces: An Integrated Experimental and Simulation Approach

FRG：金属/电介质界面的单元缺陷和微观结构过程：综合实验和模拟方法

• 批准号: 1207293
• 负责人: Richard Hennig
• 金额: $ 97.69万
• 依托单位: University of Florida
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-06-15 至 2016-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1207293&HistoricalAwards=false
• 关键词: FRG; Unit; Defect; Microstructural; Processes

NON-TECHNICAL DESCRIPTION: Lead-based dielectric materials continue to be the used in many electronic devices for communication, sonar, non-volatile memory, and echography, despite the fact that lead is environmentally and biologically incompatible. One common metal used in these devices is platinum because it conducts electrical current well and is resistant to oxidation and high temperatures. At high temperatures it is common for mixing to occur at the interface between the lead-based materials and the platinum, which ultimately limits the properties and performance of the devices. This project is focused on understanding these effects in platinum-lead-based dielectric interfaces and using this information to produce structures with improved electrical performance. The project concurrently trains the next generation of scientists, including graduate students, undergraduate students, and high school students, in state-of-the-art experimental and computational materials science and engineering. The training of underrepresented undergraduate students and outreach to high school students through summer research projects are also a focus of this activity.TECHNICAL DETAILS: Lead-based perovskites, most prominently lead titanate and its derivatives, continue to be the dominant dielectric material for many applications despite the fact that lead is environmentally and biologically incompatible. One common metal electrode used in these devices is platinum because it is an excellent conductor and exhibits high oxidation and heat resistance. During high-temperature processing, the constitutive elements in these materials interdiffuse across the interface, controlling the development of crystallographic texture and composition and thereby defining the subsequent properties and performance characteristics. This project is focused on understanding the fundamental mechanisms at play at the metal-dielectric interface and using this mechanistic information to synthesize materials and heterostructures with controlled interfaces with improved electrical properties. A combination of experimental and computational methods is used to determine the mechanisms by which (i) lead diffuses into and out of lead titanate, and (ii) temperature-driven grain-boundary migration and texture evolution occurs at the platinum/lead titanate interface. The computational approaches include electronic structure calculations using density functional theory and atomic-scale molecular dynamics simulations. As part of the latter effort, new charge-optimized, many-body reactive potentials are being developed and disseminated to the computational community as part of the open-source LAMMPS software (http://lammps.sandia.gov/). Experimentally, phase and texture evolution during high-temperature processing are characterized using in situ diffraction techniques and diffusion across the interface is examined via quantitative electron microscopy. In addition, broadband impedance and electrical measurements are being used to determine the influence of structure on dielectric and ferroelectric behavior. The project is training the next generation of scientists in state-of-the-art experimental and computational materials science and engineering. Summer research projects will engage underrepresented undergraduate and high school students.

非技术描述：铅基介电材料继续被用于通信、声纳、非易失性存储器和回波描记术的许多电子设备中，尽管铅是环境和生物不相容的。 在这些设备中使用的一种常见金属是铂，因为它传导电流良好，并且抗氧化和高温。 在高温下，通常在铅基材料和铂之间的界面处发生混合，这最终限制了器件的性质和性能。该项目的重点是了解铂铅基介电界面中的这些效应，并利用这些信息来生产具有改进电气性能的结构。该项目同时培养下一代科学家，包括研究生，本科生和高中生，在最先进的实验和计算材料科学与工程。通过暑期研究项目，对代表性不足的本科生进行培训，并向高中生推广，也是这项活动的重点。技术优势：铅基钙钛矿，最突出的是钛酸铅及其衍生物，仍然是许多应用中的主要介电材料，尽管铅与环境和生物不相容。 在这些器件中使用的一种常见金属电极是铂，因为它是优良的导体并且表现出高的抗氧化性和耐热性。 在高温加工过程中，这些材料中的组成元素在界面上相互扩散，控制晶体织构和组成的发展，从而定义随后的性质和性能特征。该项目的重点是了解在金属-电介质界面发挥作用的基本机制，并利用这些机制信息来合成具有改善电性能的受控界面的材料和异质结构。实验和计算方法的组合被用来确定的机制，其中（i）铅扩散到钛酸铅，和（ii）温度驱动的晶界迁移和纹理演变发生在铂/钛酸铅界面。 计算方法包括使用密度泛函理论和原子尺度分子动力学模拟的电子结构计算。作为后一项工作的一部分，正在开发新的电荷优化多体反应电位，并作为开放源LAMMPS软件的一部分向计算界传播（http：//lammps.sandia.gov/）。 在实验上，在高温加工过程中的相和织构的演变，其特征在于使用原位衍射技术和扩散通过定量电子显微镜检查整个界面。此外，宽带阻抗和电测量正在被用来确定结构对介电和铁电行为的影响。该项目正在培养下一代科学家在国家的最先进的实验和计算材料科学和工程。暑期研究项目将吸引代表性不足的本科生和高中生。