Southern Cross Geoscience, Southern Cross University, PO Box 157, Military Road, Lismore, NSW 2480, Australia.
School of Engineering, Deakin University, 75 Pigdons Road, Waurn Ponds, VIC 3216, Australia.
J Phys Chem Lett. 2023 May 18;14(19):4517-4523. doi: 10.1021/acs.jpclett.2c03192. Epub 2023 May 9.
For more than 150 years, our understanding of solid-phase mineral formation from dissolved constituent ions in aqueous environments has been dominated by classical nucleation theory (CNT). However, an alternative paradigm known as non-classical nucleation theory (NCNT), characterized by the existence of thermodynamically stable and highly hydrated ionic "prenucleation clusters" (PNCs), is increasingly invoked to explain mineral nucleation, including the formation of calcium carbonate (CaCO) minerals in aqueous conditions, which is important in a wide range of geological and biological systems. While the existence and role of PNCs in aqueous nucleation processes remain hotly debated, we show, using in situ small-angle X-ray scattering (SAXS), that nanometer-sized clusters are present in aqueous CaCO solutions ranging from thermodynamically under- to supersaturated conditions regarding all known mineral phases, thus demonstrating that CaCO mineral formation cannot be explained solely by CNT under the conditions examined.
150 多年来，我们对溶解在水溶液中的固体矿物成分离子的固相形成的理解一直受到经典成核理论（CNT）的支配。然而，另一种被称为非经典成核理论（NCNT）的范式越来越多地被用来解释矿物成核，包括碳酸钙（CaCO）在水溶液中的形成，这在广泛的地质和生物系统中都很重要。虽然在水相成核过程中 PNC 的存在和作用仍存在争议，但我们使用原位小角 X 射线散射（SAXS）表明，纳米级大小的团簇存在于热力学过饱和到过饱和的 CaCO 水溶液中，涉及所有已知的矿物相，因此证明在研究条件下，CaCO 矿物的形成不能仅用 CNT 来解释。
