Multidimensional structural variation in the cyanotrichite family of merotypes: camerolaite-3b-F\bar 1
| Autor: | Georges Favreau, Valérie Galéa-Clolus, Andrew G. Christy, Stuart J. Mills |
|---|---|
| Rok vydání: | 2017 |
| Předmět: |
Chemistry
Metals and Alloys Alternation (geometry) Crystal structure 010502 geochemistry & geophysics 010403 inorganic & nuclear chemistry 01 natural sciences Atomic and Molecular Physics and Optics 0104 chemical sciences Electronic Optical and Magnetic Materials Phase coupling Crystallography Diffuse scattering Octahedron Materials Chemistry Angstrom Structural unit 0105 earth and related environmental sciences |
| Zdroj: | Acta Crystallographica Section B Structural Science, Crystal Engineering and Materials. 73:950-955 |
| ISSN: | 2052-5206 |
| Popis: | A new superstructure of the mineral camerolaite, Cu6Al3(OH)18(H2O)2[Sb(OH)6](SO4), has been refined in space group P\bar 1 with unit-cell parameters aP = 7.7660 (16), bP = 8.759 (4), cP = 11.306 (2) Å, α P = 108.67 (4), β P = 83.41 (3), γ P = 126.64 (2)°, V = 581.6 (3) Å3 and Z = 1, with R 1 = 0.0951 (all data). This is the first refined example of a cyanotrichite-group mineral in which long-range order of interlayer anions produces a superstructure along b, although diffuse scattering has previously been reported that corresponds to short-range order. Though the structure shares with other members of the cyanotrichite group a structural unit in which ribbons of edge-sharing Cu and Al octahedra form layers || (001), the superstructure arises from regular alternation of [SO4] and [Sb(OH)6] polyhedra along rods that lie between the layers, and phase coupling between rods that maximizes the distance between [SO4] groups of adjacent rods along a and c directions. This arrangement suggests an alternative nearly orthogonal choice of unit cell in F\bar 1 with parameters aF = 12.473 (26), bF = 8.759 (4), cF = 21.476 (7) Å, α F = 85.94 (4), β F = 95.91 (5), γ F = 92.34 (9)°, which is recommended for comparing this structural variety of camerolaite with other members of the group. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|