Confronting Complexity in Intermetallics: A Synthetic, Structural and Theoretical Approach

面对金属间化合物的复杂性：一种合成、结构和理论方法

• 批准号: 0504703
• 负责人: Stephen Lee
• 金额: $ 33万
• 依托单位: Cornell University
• 依托单位国家: 美国
• 项目类别: Continuing grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-07-01 至 2009-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0504703&HistoricalAwards=false
• 关键词: Confronting; Complexity; Intermetallics; Synthetic; Structural

TECHNICAL EXPLANATION This project addresses the synthesis, structural characterization, properties, and band calculations for, are phases in which there are lattice mismatches between two metal structural motifs (noble metal gamma-brass superstructures), large cubic phases which can be decomposed into simpler components, phases composed of concentric icosahedral symmetry clusters, and structures composed of extended electron deficient clusters. All these systems lay near the metal-insulator boundary, some on one side, some on the other, have complex scaling properties, and potentially contain interfaces between their more metallic (covalent) and more ionic components. They test the boundaries of current paradigms useful for pure metals, insulators or semiconductors. Students working on this project will learn how to apply modern electronic structure calculations to understand the complex crystal structures that can now be obtained through modern synchrotron radiation diffraction experiments.NON-TECHNICAL EXPLANATIONThe classic alloys of civilization, brass and bronze, the elements, copper silver and gold lie at the heart of the proposed project. Our understanding today of their structures is remarkably still often imbedded in classical notions: the Platonic polyhedra for example. This project aims at a coherent structural reworking of these structures and the other structures derived from them. It will be a reworking from a classical geometrical picture (still used in understanding structures of gamma-brass for example), to paradigms based on simple quantum mechanical calculations. It is anticipated that the understanding will evolve into models based on minimal surfaces and interlocking intermeshed substructures. The materials being studied are chosen not just because they have hitherto proven difficult to understand but also because we think that such materials possess an unusual balance of bonding trends that could very well lead to materials with novel properties such as segregation between ionic and metallic components , and sub-lattice shear patterns, properties which affect the electrical and magnetic and cohesion properties of these essential alloys.

技术说明该项目致力于合成、结构表征、性质和能带计算，其中两个金属结构图案（贵金属伽马黄铜上部结构）之间存在晶格不匹配的相，可以分解为更简单的组件的大立方相，由同心二十面体对称簇组成的相，以及由扩展的缺电子簇组成的结构。所有这些系统都位于金属-绝缘体边界附近，有些在一侧，有些在另一侧，具有复杂的缩放特性，并且可能在其更多金属（共价）和更多离子组分之间包含界面。他们测试了适用于纯金属、绝缘体或半导体的当前范式的边界。从事该项目的学生将学习如何应用现代电子结构计算来理解现在可以通过现代同步加速器辐射衍射实验获得的复杂晶体结构。非技术解释文明的经典合金，黄铜和青铜，元素，铜银黄金是拟议项目的核心。 我们今天对它们结构的理解仍然经常植根于经典概念：例如柏拉图多面体。该项目旨在对这些结构以及由它们派生的其他结构进行连贯的结构改造。 它将是从经典几何图（例如仍然用于理解伽马黄铜结构）到基于简单量子力学计算的范式的改造。预计这种理解将演变成基于最小曲面和互锁的啮合子结构的模型。选择正在研究的材料不仅是因为迄今为止证明它们难以理解，而且还因为我们认为此类材料具有不寻常的键合趋势平衡，这很可能导致材料具有新颖的特性，例如离子和金属成分之间的分离，和亚晶格剪切模式，影响这些基本合金的电学、磁学和内聚性能的特性。