直接观察Zn(CN) 2中负热膨胀的横向振动机制:一个原子对分布函数分析
Karena W Chapman1, Peter J Chupas, Cameron J Kepert
1School of Chemistry, University of Sydney, Sydney, NSW 2006 Australia.
Journal of the American Chemical Society
|November 3, 2005
概括
在Zn(CN) 2中,负热膨胀 (NTE) 是由桥的横向位移增加引起的. 这种结构性洞察力解释了NTE尽管个体债券扩张.
科学领域:
- 材料科学 材料科学 材料科学
- 固态化学 固态化学
- 晶体学 晶体学是指结晶学.
背景情况:
- 负热膨胀 (NTE) 材料具有独特的特性.
- 了解NTE的原子层机制对于材料设计至关重要.
- 化 (Zn(CN) 2) 是一种具有复杂框架结构的已知NTE材料.
研究的目的:
- 为了研究Zn的即时原子结构.
- 阐明Zn中负热膨胀的微观起源2.
- 为了将结构动力学与宏观热膨胀行为相关联.
主要方法:
- 原子对分布函数 (PDF) 的分析.
- 高能X射线散射的实验. 高能X射线散射的实验.
- 温度依赖的结构分析 (100-400K).
主要成果:
- PDF分析显示,随着温度的增加,化物桥梁的横向位移增加.
- 这种位移允许非最近邻近距离 (Zn...Zn', Zn...C/N) 的收缩.
- 观察到个人债券长度 (Zn-C/N,C-N) 的扩大.
结论:
- 该研究证实,桥梁原子的平均位移增加是中NTE的起源.
- 在较高温度下,NTE的轻微减少归因于相互透的框架相互作用.
- 提供了Zn(CN) 2中NTE机制的最终结构证据.
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