在热电材料中纳米结构,组成波动和原子排序AgPb{\displaystyle AgPb}m) 和SbTe{\displaystyle SbTe}2+m). 固体解决方案的神话 固体解决方案的神话
Eric Quarez1, Kuei-Fang Hsu, Robert Pcionek
1Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, USA.
Journal of the American Chemical Society
|June 23, 2005
概括
反银 (LAST-m) 热电材料不是固体溶液,而是纳米级复合材料. 这一发现挑战了以前的信念,为设计高性能热电材料提供了新的途径.
科学领域:
- 材料科学 材料科学 材料科学
- 固态化学 固态化学
- 纳米技术 纳米技术
背景情况:
- 热电材料对于能量转换至关重要.
- 抗银 (LAST-m) 化合物以前被认为是固体溶液.
- 了解它们的纳米结构是优化热电特性的关键.
研究的目的:
- 为了研究LAST-m热电材料的原子和纳米结构.
- 为了确定LAST-m材料是否表现为固体溶液或表现出纳米级的不均性.
- 为设计改进的热电材料提供见解.
主要方法:
- 粉末和单晶X射线衍射. 粉末和单晶X射线衍射.
- 电子衍射 电子衍射.
- 高分辨率传输电子显微镜.
主要成果:
- LAST-m材料是纳米级复合材料,而不是固体溶液.
- 富含银和的少数阶段嵌入了多数阶段.
- 在纳米领域内观察到Ag,Pb和Sb原子的广泛远程排序.
- 单晶X射线衍射揭示了比以前假定的更低对称的空间群.
结论:
- 几十年来一直认为LAST-m系统是固体解决方案的假设是不正确的.
- LAST-m 材料表现出纳米级阶段分离.
- 这些发现为设计高性能热电材料提供了新的概念基础.
相关概念视频
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...
Solid–Solid Solutions
The temperature-composition phase diagram of two solids, A and B, which are immiscible in the solid phase but form miscible liquids, shows that when the temperature is low, these two exist as separate, pure solids (A and B). As the temperature increases, they transition into a single-phase liquid solution where A and B coexist. Moving from point a1 to a2 in the phase diagram, the composition changes such that solid B begins to separate from the solution, enriching the remaining liquid with A.
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...


