Thermal decomposition of iron oleate is a simple and widespread method for synthesizing monodispersed iron oxide nanoparticles (IONPs) with well‐defined morphology. However, the complexity of the underlying mechanism makes this method rather sensitive to variations in experimental conditions, and the lack of simple techniques to monitor the reaction progress in situ usually results in poor reproducibility and time‐consuming optimizations. Here, a simple, robust, and versatile in situ marker to monitor particle formation based on a sudden change in the temperature during reflux is reported. A linear relationship between the onset of particle formation and the concentration of surfactants is unveiled, corroborating a ‘chemically activated’ burst nucleation mechanism. Using this linear relationship as a guide, highly uniform spherical, cubic, and star‐shaped particles between 12 and 30 nm can be obtained. This temperature marker and the derived linear relationship not only deepen the understanding of the reaction process, but also provide a powerful tool for the straightforward optimization of IONPs.

中文翻译：

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一种简单的原位标记指导氧化铁纳米颗粒的形状控制合成


油酸铁的热分解是合成具有明确形貌的单分散氧化铁纳米粒子（IONP）的简单而广泛的方法。然而，潜在机制的复杂性使得该方法对实验条件的变化相当敏感，并且缺乏原位监测反应进程的简单技术通常会导致重现性差和耗时的优化。在此，报道了一种简单、稳健且多功能的原位标记物，用于根据回流过程中温度的突然变化来监测颗粒的形成。颗粒形成的开始与表面活性剂浓度之间的线性关系被揭示，证实了“化学激活”的爆发成核机制。以这种线性关系为指导，可以获得 12 至 30 nm 之间高度均匀的球形、立方体和星形颗粒。该温度标记和推导的线性关系不仅加深了对反应过程的理解，而且为 IONP 的直接优化提供了强大的工具。