ZnO纳米晶的生长动力学:一些惊喜
Ranjani Viswanatha1, Heinz Amenitsch, D D Sarma
1Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012, India.
Journal of the American Chemical Society
|March 22, 2007
概括
研究人员发现了氧化 (ZnO) 纳米晶体的独特生长动力学,与其他半导体纳米晶体不同. 这种新的行为归因于离子 (Na+) 形成了被动化层,减缓了纳米晶体的生长.
科学领域:
- 材料科学 材料科学 材料科学
- 纳米技术 纳米技术
- 化学工程是化学工程的重要组成部分.
背景情况:
- 半导体纳米晶体生长动力学通常由扩散控制的奥斯瓦尔德成熟或表面反应机制来解释.
- 现有的文献缺乏对氧化物 (ZnO) 等特定纳米晶体系统中观察到的独特生长行为的全面理解.
研究的目的:
- 调查和阐明ZnO纳米晶体的独特生长动力学.
- 识别导致已建立的纳米晶体生长理论偏离的潜在机制.
- 探索特定的反应剂度和温度对ZnO纳米晶体形成的作用.
主要方法:
- 广泛的ZnO纳米晶体的实验合成.
- 合成参数的系统变化,包括温度和反应剂度.
- 对增长率的分析和与理论模型的比较.
主要成果:
- ZnO纳米晶体生长动力学表现出独特的,非单调的依赖氧化离子 (OH-) 度和温度.
- 观察到的生长速度明显低于扩散控制的奥斯瓦尔德成熟或表面反应模型预测的速度.
- 证据表明反应物的抑制,归因于由离子 (Na+) 形成的被动化层,作为一个虚拟的封闭外.
结论:
- ZnO纳米晶体的生长由以前未对半导体纳米晶体描述的新机制控制.
- 离子 (Na+) 通过形成被动化层,发挥关键的抑制作用,显著改变生长动力学.
- 这一发现需要对ZnO和潜在的其他半导体纳米晶体生长的现有模型进行修订.
相关概念视频
Crystal Growth: Principles of Crystallization
Crystallization is a phase transformation process in which crystals are precipitated from a supersaturated solution or formed from other sources. During crystallization, atoms or molecules arrange themselves into a well-defined, rigid crystal lattice to minimize energy.
Initiating crystallization involves manipulating the concentration of the solute and the temperature of the solution. Since crystal growth occurs when the ratio of concentration and solubility of the solute in the solvent – the...
Initiating crystallization involves manipulating the concentration of the solute and the temperature of the solution. Since crystal growth occurs when the ratio of concentration and solubility of the solute in the solvent – the...
Ziegler–Natta Chain-Growth Polymerization: Overview
Ziegler–Natta polymerization is another form of addition or chain‐growth polymerization used for synthesizing linear polymers over branched polymers. The catalyst used for polymerization is the Ziegler–Natta catalyst, named after Karl Ziegler and Giulio Natta, who developed it in 1953. This catalyst is an organometallic complex of titanium tetrachloride and triethyl aluminum, with the active form of the catalyst being an alkyl titanium compound. Using the Ziegler–Natta catalyst, high molecular...
Colloidal precipitates
The high insolubility of some precipitates can result in an unfavorable relative supersaturation. This can lead to colloidal particles with a large surface-to-mass ratio, where adsorption is promoted. For instance, in the precipitation of silver chloride, silver ions are adsorbed on the surface of the colloidal particles, forming a primary layer. This layer attracts ions of opposite charge (such as nitrate ions), forming a diffuse secondary layer of adsorbed ions. This electric double layer...


