Secondary Particle Formation during the Nonaqueous Synthesis of Metal Oxide Nanocrystals.
Secondary Particle Formation during the Nonaqueous Synthesis of Metal Oxide Nanocrystals.
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DOI：
10.1021/acs.langmuir.8b00020
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发表时间：
2018-10
期刊：
影响因子：
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通讯作者：
P. Stolzenburg;Benjamin Hämisch;S. Richter;K. Huber;G. Garnweitner
中科院分区：
文献类型：
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作者：
P. Stolzenburg;Benjamin Hämisch;S. Richter;K. Huber;G. Garnweitner
本研究旨在阐明 TiO2 和 ZrO2 纳米颗粒在非水合成过程中的聚集和团聚行为。我们发现氧化锆纳米颗粒成核后立即形成尺寸均质为200 nm的球形聚集体，这可能与核的亚稳态和表面自由能的降低有关。这些聚集体进一步附聚，遵循扩散限制的胶体附聚机制，该机制另外得到所得附聚物的高分形维数的支持。相比之下，TiO2 纳米颗粒随机定向并遵循反应限制的胶体团聚机制，从而在整个反应体积中形成致密的颗粒网络。我们进行了原位激光光透射测量，结果表明颗粒形成的开始时间比之前报道的要早。开发了一个复杂的种群平衡方程模型，能够模拟颗粒聚集和团聚，最终使我们能够区分这两种现象。因此，我们能够研究各自的团聚动力学，与我们的实验数据非常一致。
This study aims to elucidate the aggregation and agglomeration behavior of TiO2 and ZrO2 nanoparticles during the nonaqueous synthesis. We found that zirconia nanoparticles immediately form spherical-like aggregates after nucleation with a homogeneous size of 200 nm, which can be related to the metastable state of the nuclei and the reduction of surface free energy. These aggregates further agglomerate, following a diffusion-limited colloid agglomeration mechanism that is additionally supported by the high fractal dimension of the resulting agglomerates. In contrast, TiO2 nanoparticles randomly orient and follow a reaction-limited colloid agglomeration mechanism that leads to a dense network of particles throughout the entire reaction volume. We performed in situ laser light transmission measurements and showed that particle formation starts earlier than previously reported. A complex population balance equation model was developed that is able to simulate particle aggregation as well as agglomeration, which eventually allowed us to distinguish between both phenomena. Hence, we were able to investigate the respective agglomeration kinetics with great agreement to our experimental data.