Crystal structure of vyacheslavite, U(PO₄)(OH), solved from natural nanocrystal: a precession electron diffraction tomography (PEDT) study and DFT calculations

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.

Meet the Cerium(IV) Phosphate Sisters: CeIV(OH)PO4 and CeIV2O(PO4)2

“…The structure of Ce(OH)PO 4 contains large channels, with a diameter of about 3 .A ccording to the data of Steciuk et al, [45] crystallization water is absenti nt he compositiono f the isostructuralU (OH)PO 4 .N ote that Steciuke tal. obtained these data by analyzing the structure of the natural mineral vyacheslavite, to which the U(OH)PO 4 •2H 2 Oc omposition was previously assigned,w ithp recession electron diffractiont omography.…”

“…The structure of Ce(OH)PO 4 contains large channels, with a diameter of about 3 Å. According to the data of Steciuk et al., crystallization water is absent in the composition of the isostructural U(OH)PO 4 . Note that Steciuk et al.…”

Hydrogen disorder in kaatialaite Fe[AsO2(OH)2]5H2O from Jáchymov, Czech Republic: determination from low-temperature 3D electron diffraction

“…By comparison with organic materials, the difference potential map appears noisier because heavier atoms are present. In the work of Steciuk et al (2019), the hydrogen position in the mineral vyacheslavite U(PO 4 )(OH) was visible from the difference potential map after the dynamical refinement despite the presence of quite strong surrounding artifacts, and this position was further confirmed by density-functionaltheory calculations. In Fig.…”

“…Most of the works published were carried out on organic samples where dynamical diffraction effects are weaker because of the presence of atoms having weak scattering power. However, with the example of the mineral vyacheslavite, U(PO 4 )(OH), the dynamical refinement proved its efficiency in determining hydrogen positions, even among the heaviest atoms like uranium (Steciuk et al, 2019). The current implementation of the dynamical theory in refining the structure leads to very good accuracy but it assumes perfect crystallinity that is often not the case for natural minerals.…”

Hydrogen bonding in the crystal structure of phurcalite, Ca2[(UO2)3O2(PO4)2]·7H2O: single-crystal X-ray study and TORQUE calculations

“…In the second set the H 2 O molecules are oriented randomly while preserving the molecular H 2 O geometry and addresses the (non)uniqueness of the identified rotational equilibria. We optimized 1000 random initial H 2 O orientations and statistically analyzed the similarities and differences of the obtained rotational equilibrium configurations, similar to our previous work (Ghazisaeed et al, 2018(Ghazisaeed et al, , 2019(Ghazisaeed et al, , 2020Steciuk et al, 2019). Moreover, we performed an additional TORQUE optimiza- Crystal structure of phurcalite.…”