The interaction between the spreading of a hydrofluoric acid-based drop on a glass surface and its etching rate gives rise to hollow crystals of various shapes, including cubes, triangles, and icosahedra. These geometries are dependent on their position with respect to the contact line, where a rim forms by agglutination, similar to the formation of a coffee stain. Atomic force microscopy indentation and transmission electron microscopy observations revealed that these crystals are hollow ammonium-fluosilicate-based cryptohalite shells. © 2012 American Chemical Society.
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledgements: S.C. thanks R. Haasch for XPS assistance, M. Sardela for his comments on the X-ray spectra, B. Cunningham for lending us the reflectance measurement equipment, and S. Salapaka for the AFM measurements. These experimental characterizations were carried out in the Center for Microanalysis of Materials, University of Illinois, which is partially supported by the U.S. Department of Energy under Grant DEFG02-91-ER45439. S.B. is an undergraduate at the department of material science and engineering.
ASJC Scopus subject areas
- Materials Science(all)
- Condensed Matter Physics