Issue 24, 2023

Electron transparent nanotubes reveal crystallization pathways in confinement

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.

Graphical abstract: Electron transparent nanotubes reveal crystallization pathways in confinement

Supplementary files

Article information

Article type
Edge Article
Submitted
15 fev 2023
Accepted
13 may 2023
First published
30 may 2023
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY license

Chem. Sci., 2023,14, 6705-6715

Electron transparent nanotubes reveal crystallization pathways in confinement

J. M. Galloway, Z. P. Aslam, S. R. Yeandel, A. Kulak, M. A. Ilett, Y. Kim, A. Bejarano-Villafuerte, B. Pokroy, R. M. Drummond-Brydson, C. L. Freeman, J. H. Harding, N. Kapur and F. C. Meldrum, Chem. Sci., 2023, 14, 6705 DOI: 10.1039/D3SC00869J

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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