Electron transparent nanotubes reveal crystallization pathways in confinement

Johanna M. Galloway, Zabeada P. Aslam, Stephen R. Yeandel, Alexander Kulak, Martha A. Ilett, Yi Yeoun Kim, Angela Bejarano-Villafuerte, Boaz Pokroy, Rik M. Drummond-Brydson, Colin L. Freeman, John H. Harding, Nikil Kapur, Fiona C. Meldrum

Research output: Contribution to journalArticlepeer-review

Abstract

The cylindrical pores of track-etched membranes offer excellent environments for studying the effects of confinement on crystallization as the pore diameter is readily varied and the anisotropic morphologies can direct crystal orientation. However, the inability to image individual crystals in situ within the pores in this system has prevented many of the underlying mechanisms from being characterized. Here, we study the crystallization of calcium sulfate within track-etched membranes and reveal that oriented gypsum forms in 200 nm diameter pores, bassanite in 25-100 nm pores and anhydrite in 10 nm pores. The crystallization pathways are then studied by coating the membranes with an amorphous titania layer prior to mineralization to create electron transparent nanotubes that protect fragile precursor materials. By visualizing the evolutionary pathways of the crystals within the pores we show that the product single crystals derive from multiple nucleation events and that orientation is determined at early reaction times. Finally, the transformation of bassanite to gypsum within the membrane pores is studied using experiment and potential mean force calculations and is shown to proceed by localized dissolution/reprecipitation. This work provides insight into the effects of confinement on crystallization processes, which is relevant to mineral formation in many real-world environments.

Original languageEnglish
Pages (from-to)6705-6715
Number of pages11
JournalChemical Science
Volume14
Issue number24
DOIs
StatePublished - 30 May 2023

All Science Journal Classification (ASJC) codes

  • General Chemistry

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