自组装的简单六边形AB(2) 双纳米晶超网格:SEM,GISAXS和缺陷
Danielle K Smith1, Brian Goodfellow, Detlef-M Smilgies
1Department of Chemical Engineering, Texas Materials Institute, Center for Nano- and Molecular Science and Technology, The University of Texas at Austin, Austin, Texas 78712-1062, USA.
Journal of the American Chemical Society
|February 17, 2009
概括
由氧化铁和金纳米晶体组成的二进制超级网格 (BSL) 成功组装. 这些结构呈现出简单的六角形AB(2) 排列,在沉积时观察到格子收缩和对称性变化.
科学领域:
- 材料科学 材料科学 材料科学
- 纳米技术 纳米技术
- 晶体学 晶体学是指结晶学.
背景情况:
- 二元超级网格 (BSL) 通过对不同尺寸的纳米粒子的控制排列提供可调节的特性.
- 纳米晶体的自组装是创建有序纳米材料的关键策略.
- 了解BSL的结构细微差别对于其应用至关重要.
研究的目的:
- 组装和表征二元超级网 (BSL) 的氧化铁和金纳米晶体.
- 阐明组装的BSL的结构顺序和对称性.
- 为了研究基质相互作用和干燥对BSL结构的影响.
主要方法:
- 在倾斜的基板上缓慢蒸发的合分散物.
- 传输电子显微镜 (TEM) 和扫描电子显微镜 (SEM) 用于结构分析.
- 草地发生率小角度X射线散射 (GISAXS) 用于远程顺序和结构参数.
主要成果:
- 简单的六角形 (sh) AB(2) 二元超格的组装 (与AlB(2) 构成结构).
- 长距离顺序的确认和纳米晶体排列的识别 (大Fe(2) O(3) 在格子中,小Au在间歇点中).
- 观察由于溶剂干燥而垂直于基质的超晶格收缩 (8-12%),导致在 (100) 平面上以中心为中心的正方体对称.
- 标识由插入金纳米晶半平面组成的超级格子位移.
结论:
- 铁二三和纳米晶BSL可以组装成有序的sh-AB二结构.
- 溶剂干燥会导致显著的结构收缩和对称性变化.
- 这项研究提供了关于纳米晶体超级的自我组装机制和结构稳定性的见解.
相关概念视频
Lattice Centering and Coordination Number
The structure of a crystalline solid, whether a metal or not, is best described by considering its simplest repeating unit, which is referred to as its unit cell. The unit cell consists of lattice points that represent the locations of atoms or ions. The entire structure then consists of this unit cell repeating in three dimensions. The three different types of unit cells present in the cubic lattice are illustrated in Figure 1.
Types of Unit Cells
Imagine taking a large number of identical...
Types of Unit Cells
Imagine taking a large number of identical...
Metallic Solids
Metallic solids such as crystals of copper, aluminum, and iron are formed by metal atoms. The structure of metallic crystals is often described as a uniform distribution of atomic nuclei within a “sea” of delocalized electrons. The atoms within such a metallic solid are held together by a unique force known as metallic bonding that gives rise to many useful and varied bulk properties.
All metallic solids exhibit high thermal and electrical conductivity, metallic luster, and malleability. Many...
All metallic solids exhibit high thermal and electrical conductivity, metallic luster, and malleability. Many...
Imperfections in Crystal Structure: Stoichiometric Point Defects
Schottky defects arise when some lattice points in a crystal, such as those in NaCl, remain unoccupied, creating lattice vacancies without disturbing the overall electrical neutrality of the crystal. This defect is common in ionic crystals where the positive and negative ions are similar in size, as seen in sodium chloride and cesium chloride. The presence of Schottky defects enables the crystal to conduct electricity to a small extent through an ionic mechanism. Electric fields cause nearby...
Ionic Crystal Structures
Ionic crystals consist of two or more different kinds of ions that usually have different sizes. The packing of these ions into a crystal structure is more complex than the packing of metal atoms that are the same size.
Most monatomic ions behave as charged spheres, and their attraction for ions of opposite charge is the same in every direction. Consequently, stable structures for ionic compounds result (1) when ions of one charge are surrounded by as many ions as possible of the opposite...
Most monatomic ions behave as charged spheres, and their attraction for ions of opposite charge is the same in every direction. Consequently, stable structures for ionic compounds result (1) when ions of one charge are surrounded by as many ions as possible of the opposite...
Structures of Solids
Solids in which the atoms, ions, or molecules are arranged in a definite repeating pattern are known as crystalline solids. Metals and ionic compounds typically form ordered, crystalline solids. A crystalline solid has a precise melting temperature because each atom or molecule of the same type is held in place with the same forces or energy. Amorphous solids or non-crystalline solids (or, sometimes, glasses) which lack an ordered internal structure and are randomly arranged. Substances that...
Imperfections in Crystal Structure: Point, Line and Plane Defects
A perfect crystal, in theory, has a uniform structure with the same unit cell and lattice points throughout. However, any deviation from this periodic arrangement is known as an imperfection or defect. These defects can be categorized into three types: point, line, and plane defects.Point defects occur when there is a deviation from the ideal due to missing atoms, displaced atoms, or additional atoms. These imperfections might occur due to imperfect packing during crystallization or because of...


