Crystal structure of the uranyl arsenate mineral hügelite, Pb2(UO2)3O2(AsO4)2(H2O)5, revisited: a correct unit cell, twinning and hydrogen bonding
| Autor: | Pavel Škácha, Václav Petříček, Jakub Plášil |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2021 |
| Předmět: |
crystal structure
twinning Crystal structure 010502 geochemistry & geophysics 010403 inorganic & nuclear chemistry 01 natural sciences Crystal chemistry.chemical_compound uranyl arsenate reticular merohedry Materials Chemistry 0105 earth and related environmental sciences Hydrogen bond Metals and Alloys Arsenate Uranyl Research Papers Atomic and Molecular Physics and Optics 0104 chemical sciences Electronic Optical and Magnetic Materials Crystallography chemistry JANA2006 Supercell (crystal) hügelite Crystal twinning Monoclinic crystal system |
| Zdroj: | Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials |
| ISSN: | 2052-5206 2052-5192 |
| Popis: | The crystal structure of the uranyl arsenate mineral hügelite is affected by twinning due to reticular merohedry (diffraction type II). This study documents, apart from the correct description of the unit cell and the nature of the twinning, the possibilities of the JANA2006 program in revealing the real nature of twinning even if using published structural data without the original reflection files. Revisiting the structure of uranyl arsenate mineral hügelite provided some corrections to the available structural data. The previous twinning model (by reticular merohedry) in hügelite has been corrected. Twinning of the monoclinic unit cell [a = 7.0189 (7) Å, b = 17.1374 (10) Å, c = 8.1310 (10) Å and β = 108.904 (10)°], which can be expressed as a mirror in [100], leads to a pseudo-orthorhombic unit cell (a = 7.019 Å, b = 17.137 Å, c = 61.539 Å and β = 90.02°), which is eight times larger, with respect to the unit-cell volume, than a real cell. Moreover, the unit cell of chosen here and the unit cell given by the previous structure description both lead to the same supercell. A new structure refinement undertaken on an untwinned crystal of hügelite resulted in R = 4.82% for 12 864 reflections with I obs > 3σ(I) and GOF = 1.12. The hydrogen-bonding scheme has been proposed for hügelite for the first time. |
| Databáze: | OpenAIRE |
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