Yoko Akira, Han Chunli, Sakonaka Ayame, Seong Gimyeong, Tomai Takaaki, Ohara Satoshi, Adschiri Tadafumi
International Center for Synchrotron Radiation Innovation Smart (SRIS), Tohoku University, 468-1 Aramaki Aza-Aoba, Aoba-ku, Sendai 980-8572, Japan.
WPI-Advanced Institute for Materials Research (WPI-AIMR), Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan.
Precis Chem. 2025 Apr 17;3(7):372-379. doi: 10.1021/prechem.5c00004. eCollection 2025 Jul 28.
The nonequilibrium composition and its formation process are critical aspects of nanoparticle production technology. Understanding the dynamics of nanoparticle formation under nonequilibrium conditions is essential. In this study, Cr-doped CeO nanoparticles are synthesized via continuous-flow hydrothermal synthesis at various temperatures (300, 350, 400 °C) with reaction times precisely controlled on the order of seconds. At the initial stage of particle formation, Cr-rich CeO particles form due to a low surface energy. Over time, the Cr content decreases as the particles relax toward the equilibrium structure. This process yields an unusual nonequilibrium composition through rapid heating and short residence times. Similar nonequilibrium compositions are also observed for other dopants, such as Fe and Eu. Continuous-flow hydrothermal synthesis thus presents an efficient method for fabricating nanomaterials with unique compositions that are unattainable using conventional batch methods.
非平衡组成及其形成过程是纳米颗粒生产技术的关键方面。了解非平衡条件下纳米颗粒形成的动力学至关重要。在本研究中，通过连续流热液合成法在不同温度（300、350、400℃）下合成了Cr掺杂的CeO纳米颗粒，反应时间精确控制在秒级。在颗粒形成的初始阶段，由于表面能低，形成了富Cr的CeO颗粒。随着时间的推移，随着颗粒向平衡结构弛豫，Cr含量降低。这个过程通过快速加热和短停留时间产生了一种不寻常的非平衡组成。对于其他掺杂剂，如Fe和Eu，也观察到了类似的非平衡组成。因此，连续流热液合成法为制备具有独特组成的纳米材料提供了一种有效的方法，而这些组成是传统批量方法无法实现的。
