In Situ Study on the Evolution of Multimodal Particle Size Distributions of ZnO Quantum Dots: Some General Rules for the Occurrence of Multimodalities
In Situ Study on the Evolution of Multimodal Particle Size Distributions of ZnO Quantum Dots: Some General Rules for the Occurrence of Multimodalities
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DOI：
10.1021/acs.jpcb.5b08005
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发表时间：
2015-12-10
影响因子：
3.3
通讯作者：
Unruh, Tobias
中科院分区：
文献类型：
--
作者：
Schindler, Torben;Walter, Johannes;Unruh, Tobias
小的半导体纳米颗粒（NPs）的性质在很大程度上取决于它们的尺寸。精确的表征是定制色散的关键要求，因此也是高质量器件的关键要求。ZnO的粒度分布（PSD）的仔细分析的结果结合紫外/维斯吸收光谱，分析超吸收，和小角X射线散射（SAXS）的优点。我们的研究表明，这些不同方法的仔细交叉验证是强制性的，以最终获得可靠的解决方案。ZnO NP的PSD在2-8 nm的尺寸范围上是多峰的，这一发现尚未得到充分解决。在我们工作的第二部分中，使用原位小角X射线散射研究了PSD的演化。发现了覆盖15至45摄氏度之间的温度范围的多模态外观的一般原则，其仅由中等大小部分的大小所指示的老化状态决定。每当这个分数超过一个临界直径，一个新的多模态被识别，独立于特定的时间温度组合。在检测到一部分较小颗粒之前，一部分较大颗粒首先聚集。固定多模态尚未得到充分解决，只能通过仔细的尺寸分析来证明。
Properties of small semiconductor nanoparticles (NPs) are strongly governed by their size. Precise characterization is a key requirement for tailored dispersities and thus for high-quality devices. Results of a careful analysis of particle size distributions (PSDs) of ZnO are presented combining advantages of UV/vis absorption spectroscopy, analytical ultracentrifugation, and small-angle X-ray scattering (SAXS). Our study reveals that careful cross-validation of these different methods is mandatory to end up with reliable resolution. PSDs of ZnO NPs are multimodal on a size range of 2-8 nm, a finding that is not yet sufficiently addressed. In the second part of our work the evolution of PSDs was studied using in situ SAXS. General principles for the appearance of multimodalities covering a temperature range between 15 and 45 degrees C were found which are solely determined by the aging state indicated by the size of the medium-sized fraction. Whenever this fraction exceeds a critical diameter, a new multimodality is identified, independent of the particular time temperature combination. A fraction of larger particles aggregates first before a fraction of smaller particles is detected. Fixed multimodalities have not yet been addressed adequately and could only be evidenced due to careful size analysis.