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Updated: Sep 24, 2025
High Pressure Single Crystal Diffraction at PX^2
Published on: January 16, 2017
Crystal structure of vyacheslavite, U(PO4)(OH), solved from natural nanocrystal: a precession electron diffraction
Gwladys Steciuk1, Seyedayat Ghazisaeed2, Boris Kiefer2
1Institute of Physics, Academy of Sciences of the Czech Republic v.v.i, Na Slovance 2 Prague 18221 Czech Republic plasil@fzu.cz.
Abstract:
The crystal structure of the U(iv)-phosphate mineral vyacheslavite has been solved from precession electron diffraction tomography (PEDT) data from the natural nano-crystal and further refined using density-functional theory (DFT) calculations. Vyacheslavite is orthorhombic, with the space group Cmca, with a ≈ 6.96 Å, b ≈ 9.07 Å and c ≈ 12.27 Å, V ≈ 775 Å3 (obtained from PEDT data at 100 K), Z = 8. Its structure is a complex heteropolyhedral framework consisting of sheets of UO7(OH) and PO4 polyhedra, running parallel to (001), interconnected by additional PO4 polyhedra. There is an (OH) group associated with the U(iv) polyhedron. The question of H2O presence within the small cavities of the framework has been addressed by the DFT calculations, which have proved that vyacheslavite does not contain any significant amount of H2O at room temperature.
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