Exploiting Confinement to Study the Crystallization Pathway of Calcium Sulfate
Exploiting Confinement to Study the Crystallization Pathway of Calcium Sulfate
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DOI：
10.1002/adfm.202107312
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发表时间：
2021-09-14
影响因子：
19
通讯作者：
Meldrum, Fiona C.
中科院分区：
文献类型：
--
作者：
Anduix-Canto, Clara;Levenstein, Mark A.;Meldrum, Fiona C.
表征晶体形成的途径仍然是一个重大挑战，特别是当多个途径同时运行时。在这里，介绍了一种基于成像的策略，利用限制效应来跟踪3D中的晶体群体的演变，并表征结晶途径。专注于室温下水溶液中硫酸钙的形成，沉淀在纳米多孔介质中进行，这确保了晶体固定在适当位置并缓慢生长。然后可以使用同步加速器X射线计算机断层扫描和衍射计算机断层扫描原位跟踪它们的大小，形状和多晶型物的演变，而无需分离和潜在地改变晶体。研究表明，钙钛矿（CaSO4 0.5H（2）O）通过无定形前体相形成，并且在这些纳米级孔中表现出长期稳定性。此外，结晶稳定相石膏（CaSO4·2H（2）O）可根据当地物理环境通过不同途径沉淀。也获得了对纳米限制中结晶的洞察，并且看到晶体在整个纳米多孔网络中生长而不引起结构损伤。因此，这项工作为研究结晶途径提供了一种新的策略，并证明了限制对硫酸钙沉淀的重大影响，这与其在许多现实环境中的形成有关。
Characterizing the pathways by which crystals form remains a significant challenge, particularly when multiple pathways operate simultaneously. Here, an imaging-based strategy is introduced that exploits confinement effects to track the evolution of a population of crystals in 3D and to characterize crystallization pathways. Focusing on calcium sulfate formation in aqueous solution at room temperature, precipitation is carried out within nanoporous media, which ensures that the crystals are fixed in position and develop slowly. The evolution of their size, shape, and polymorph can then be tracked in situ using synchrotron X-ray computed tomography and diffraction computed tomography without isolating and potentially altering the crystals. The study shows that bassanite (CaSO4 0.5H(2)O) forms via an amorphous precursor phase and that it exhibits long-term stability in these nanoscale pores. Further, the thermodynamically stable phase gypsum (CaSO4 2H(2)O) can precipitate by different pathways according to the local physical environment. Insight into crystallization in nanoconfinement is also gained, and the crystals are seen to grow throughout the nanoporous network without causing structural damage. This work therefore offers a novel strategy for studying crystallization pathways and demonstrates the significant impact of confinement on calcium sulfate precipitation, which is relevant to its formation in many real-world environments.