CAREER: Novel Ceramic Nanocomposites with Smart Interface Design

非技术描述：CAREER计划探索陶瓷纳米复合薄膜的基本界面控制，使纳米结构的设计具有新的或显着改善的材料性能。这项研究将直接影响高温超导体（HTS） YBa2Cu3O7-ä （YBCO）涂层导体在自场和场内具有高临界电流密度的许多设想应用。所获得的基本知识也将阐明在许多其他具有异质界面的陶瓷纳米复合系统中观察到的界面现象，例如微电子和光电子器件，薄膜固体氧化物燃料电池（SOFC），薄膜太阳能电池等。本研究项目将结合以下教育目标：(1)为PI的薄膜课开发“放苹果的艺术”教学模式；(2)通过合作，为德克萨斯农工大学（TAMU）、洛斯阿拉莫斯国家实验室和休斯顿大学的本科生和研究生提供多学科培训；(3)通过以下方式将研究成果传播给更广泛的受众：(a)通过TAMU的暑期研究项目让高中教师参与研究项目；(b)通过TAMU的女性工程论坛和女性导师计划以及新墨西哥大学的洛斯阿拉莫斯暑期学校（LASS），让代表性不足的群体参与材料科学和工程。技术细节：该职业项目涉及外延陶瓷纳米复合材料中异质界面的合成、表征和工程的基础材料科学研究。本项目探讨了陶瓷纳米复合材料异质外延界面上常见的错配位错和相关缺陷，并研究了它们对材料功能的影响。本研究选择的材料体系是纳米层状和纳米颗粒掺杂的YBCO。目的是了解外延纳米复合陶瓷薄膜的界面控制，目的是设计具有独特功能的界面。首先，将对纳米层系统进行彻底的微观结构表征，其中已经观察到强界面效应。各种原子尺度表征工具的组合，包括高分辨率透射电子显微镜（TEM），扫描透射电子显微镜（STEM）和电子能量损失谱（EELS）分析将被用来识别界面上的错配位错和相关缺陷。其次，对YBCO纳米复合薄膜的错配位错密度与磁通钉扎性能之间的关系进行系统研究。最后，提出了一种受二维错配位错阵列约束的二维有序纳米粒子阵列。所有的YBCO纳米复合薄膜都将通过脉冲激光沉积（PLD）在TAMU制备。各种表征技术，如高分辨率XRD， TEM（结合STEM和EELS成分分析）以及输运性能测量将被用于研究这些YBCO纳米复合体系的结构和通量钉钉性能。

NON-TECHNICAL DESCRIPTION: The CAREER program explores the fundamental interface control in ceramic nanocomposite thin films which allow the design of nanostructures with new or significantly improved materials properties. This study will have direct impact on processing high temperature superconductor (HTS) YBa2Cu3O7-ä (YBCO)-coated conductors with high critical current density in both self-field and in-field for many envisioned applications. The fundamental knowledge gained will also illuminate the interfacial phenomena observed in many other ceramic nanocomposite systems with heterogeneous interfaces, such as microelectronic and optoelectronic devices, thin film solid oxide fuel cells (SOFC), thin film solar cells and etc.. The research program will integrate with the following educational objectives: (1) to develop a teaching model "The Art of Laying Apples" for the PI's thin film classes; (2) to offer a multidisciplinary training to undergraduate and graduate students at Texas A&M University (TAMU), and at Los Alamos National Laboratory and the University of Houston through collaboration; and (3) to disseminate the research results to a much broader audience by (a) involving high school teachers in the research project through a summer research program at TAMU; and (b) involving under-represented groups into materials science and engineering through the Women Engineering Forum and the Women Mentor Program at TAMU and the Los Alamos Summer School (LASS) at the University of New Mexico.TECHNICAL DETAILS: This CAREER project addresses fundamental materials science research on the synthesis, characterization and engineering of heterogeneous interfaces in epitaxial ceramic nanocomposites. This project explores misfit dislocations and associated defects commonly observed at heteroepitaxial interfaces in ceramic nanocomposites, and studies their impacts on material functionalities. The material systems selected for this study are nanolayered and nanoparticle-doped YBCO. The goal is to understand interface control in epitaxial nanocomposite ceramic thin films, with the objective to engineer the interfaces for unique functionalities. First, a thorough microstructural characterization will be performed on nanolayered systems where strong interfacial effects have already been observed. A combination of various atomic-scale characterization tools including high-resolution transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM) and electron energy loss spectroscopy (EELS) analysis will be employed to identify misfit dislocations and associated defects at the interfaces. Second, a systematic study to correlate the misfit dislocation density and the flux-pinning property will be conducted on YBCO nanocomposite thin films. Finally, a novel 2D ordered nanoparticle array confined by the 2D misfit dislocation array is proposed. All the YBCO nanocomposite thin films will be prepared by pulsed laser deposition (PLD) at TAMU. Various characterization techniques, such as high resolution XRD, TEM (combined with STEM and EELS compositional analysis), as well as transport property measurements will be utilized to investigate the structural and flux-pinning properties of these YBCO nanocomposite systems.