Tailoring Microstructures of High-Tc Superconducting Films

该项目致力于更好地理解阳离子交换的微观机制和新工艺PONSE（纳米级应变工程孔）。这些工艺有望为工程微结构和物理性能的几个高Tc超导体（HTS）薄膜，包括YBa_2Cu_3O_7（YBCO），Tl基（Tl-HTS）和Hg基（Hg-HTS）超导体。本论文将探讨三个主题：1）利用阳离子交换法来磊晶汞高温超导薄膜。Tl-HTS和Hg-HTS之间的阳离子交换的可逆性旨在理解阳离子交换机制和通过合金化Hg-HTS和Tl-HTS以及在晶格上添加纳米针来改善Hg-HTS薄膜的微结构的方法的应用。2)系统地研究了Tl-HTS和Hg-HTS薄膜邻位生长，重点研究了反相晶界形成的形核过程、Tl-HTS薄膜到Hg-HTS薄膜的微结构演化和阳离子交换过程中微结构的变化。微观结构/缺陷和磁钉扎之间的定量相关性将具体通过测量临界电流密度（Jc）作为温度，磁场和磁场方向的函数进行研究。3)研究了通过PONSE工艺通过邻位生长和纳米颗粒插入获得的多孔YBCO薄膜。这些超导体海绵的Jc的显著改善。提出了多孔超导体的材料科学和材料物理问题。为了回答这些问题，将研究孔形成的机制，以更好地理解和实现孔尺寸、密度、形状和分布的精确控制。多孔YBCO薄膜的超导性能将被研究，以了解孔和约化尺寸对超导电性的作用。材料科学和材料物理学的研究将以连贯的方式进行。我们的目标是实现更大的理解和高性能的YBCO薄膜所需的微观结构和超导性能。* 该项目涉及与电子和光子学技术密切相关的基础材料研究，并有效地整合了研究和教育。该项目的影响包括在纳米科学和材料科学/物理学与积极的PI强调扩大代表性不足的群体的参与下一代科学家的教育。

This project strives for greater understanding of microscopic mechanisms of cation exchange and a new process, PONSE (Pores by nanoscale strain engineering). These processes hold promise for engineering microstructures and physical properties of several high-Tc superconductor (HTS) films including YBa2Cu3O7 (YBCO), Tl-based (Tl-HTS) and Hg-based (Hg-HTS) superconductors. Three sub-topics will be investigated: 1) epitaxy of Hg- HTS films using the cation exchange process. The reversibility of cation exchange between Tl-HTSs and Hg-HTSs is aimed at understanding the cation exchange mechanism and application of the process for improving microstructures of Hg-HTS films via alloying Hg-HTS and Tl-HTS and adding nano-pins on the lattice. 2) systematic study of vicinal growth of Tl-HTS and Hg-HTS films, with focus on nucleation via anti-phase grain boundary formation, microstructure evolution and microstructure variation during cation exchange from Tl-HTS to Hg-HTS films. A quantitative correlation between microstructure/defects and magnetic pinning will be investigated specifically through measurement of critical current density (Jc) as function of temperature, magnetic field and the orientation of the magnetic field. 3) studies of porous YBCO films obtained via the PONSE process through vicinal growth and nanoparticle insertion. The significant improvement in the Jc of these .superconductor sponges. raises questions on both material science and material physics of the porous superconductors. To answer these questions, the mechanism of pore formation will be investigated for greater understanding and achievement of precise control of pore dimension, density, shape and distribution. The superconducting properties of the porous YBCO films will be studied to understand the role of pores and reduced dimension on superconductivity. The studies of material science and material physics will be carried out in a coherent fashion. The goal is to achieve greater understanding and high performance YBCO films with desired microstructures and superconducting properties. *** The project addresses fundamental materials research with strong technological relevance to electronics and photonics, and effectively integrates research and education. The impact of the project includes education of the next generation of scientists in nanoscience and material science/physics with active PI emphasis on broadening participation of underrepresented groups.