奥斯瓦尔德熟化过程的控制

Control of Ostwald ripening

作为一种热力学的必然过程,奥斯瓦尔德熟化通常会发生在材料生长的后期阶段,并导致材料的性能参数变差.几十年来,如何阻止或控制奥斯瓦尔德熟化一直是材料制备领域的一个挑战.尤其在纳米材料制备中,奥斯瓦尔德熟化已经成为了获得优良材料的一大障碍.在大量实验和分析的基础上,本文发现临界浓度和时间窗口是阻止和抑制奥斯瓦尔德熟化发生的两个关键因素.我们利用全自动纳米材料合成仪,对制备NaREF4纳米材料的过程进行一系列精确控制,探明了奥斯瓦尔德熟化的规律,将熟化划分为三种类型.通过控制奥斯瓦尔德熟化的发生,不仅获得了高质量的纳米晶体,而且还开发了核-壳纳米材料制备策略.考虑到奥斯瓦尔德熟化的普遍性,这种方法可以应用于许多纳米材料的制备过程.

As a thermodynamic process, Ostwald ripening is inevitable in solid solution or liquid sol, which usually leads to inhomogeneous morphologies and poor particle size distributions. For decades, how to prevent or control Ostwald ripening has been a challenge in material preparation, especially for obtaining excellent nanomaterials. Here, we propose two important concepts, critical concentration and time window, as the keys to inhibit Ostwald ripening occurring over a fairly long time. A series of precise controls were performed in preparing NaREF4nanomaterials by using an automatic nanomaterial synthesizer to explore the regularity in Ostwald ripening. Our results exhibit that Oswald ripening processes could be controlled exactly, which provides an effective approach for the controllable synthesis of NaREF4nanocrystals.By controlling Oswald ripening, we have not only achieved high-quality nanocrystals but also developed a strategy for core-shell preparations. Given the ubiquity of Oswald ripening, this method can be applied to many preparation processes.