环境稳定的四角形和正角形相在五双胞胎双形或微晶体中
Gangaiah Mettela1, Meha Bhogra, Umesh V Waghmare
1Thematic Unit of Excellence on Nanochemistry and Chemistry and Physics of Materials Unit and ‡Theoretical Sciences Unit, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR) , Jakkur P.O., Bangalore 560 064, India.
Journal of the American Chemical Society
|February 12, 2015
概括
研究人员在金 (Au) 微晶体中发现了新的晶体结构,以身体为中心的四角形 (bct) 和以身体为中心的正角形 (bco) 阶段. 这些非面中心立方体 (fcc) 阶段来自双金字塔金结构中的几何应变.
科学领域:
- 材料科学 材料科学 材料科学
- 固态物理 固态物理
- 纳米技术纳米技术
背景情况:
- 大量黄金通常表现出面中心立方体 (fcc) 晶体结构.
- 了解黄金的结构多样性对于高级应用至关重要.
- 之前的研究主要集中在黄金的fcc阶段.
研究的目的:
- 为了研究双金字塔形黄金微晶的晶体结构.
- 为了识别和描述任何非fcc阶段的存在.
- 了解这些新型黄金相的形成机制和稳定性.
主要方法:
- 通过 (AuCl4) 的热解合成双金字塔型Au微晶, (AuCl4) 通过四氧化酸 (ToABr) 稳定.
- 使用实验室单色X射线源来检测晶体结构的表征.
- 第一原则理论计算以支持关于相位稳定的实验发现.
主要成果:
- 在Au微晶体中发现以身体为中心的四角形 (bct) 和以身体为中心的正角形 (bco) 阶段.
- 这些非fcc阶段被观察到在双金字塔形黄金中,其尖端是五角形的双胞胎.
- 非fcc相的形成与200-250°C的温度范围内的几何诱导菌株有关.
结论:
- 双金微晶中的几何诱导应变可以稳定非fcc相 (bct和bco).
- 软模式被确定为这些非fcc Au结构在应力下温度依赖稳定的起源.
- 高温回火减轻了应变,导致非fcc相的不稳定,使黄金恢复到其典型的fcc结构.
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