The crystal structure of cyanotrichite, having general formula Cu<inf>4</inf>Al<inf>2</inf>(SO<inf>4</inf>)(OH)<inf>12</inf>·2H<inf>2</inf>O, from the Dachang deposit (China) was studied by means of conventional transmission electron microscopy, automated electron diffraction tomography (ADT) and synchrotron X-ray powder diffraction (XRPD). ADT revealed the presence of two different cyanotrichite-like phases. The same phases were also recognized in the XRPD pattern, allowing the perfect indexing of all peaks leading, after refinement to the following cell parameters: (1) a = 12.417(2) Å, b = 2.907(1) Å, c = 10.157(1) Å and β = 98.12(1); (2) a = 12.660(2) Å, b = 2.897(1) Å, c = 10.162(1) Å and β = 92.42(1)°. Only for the former phase, labeled cyanotrichite-98, a partial structure, corresponding to the [Cu<inf>4</inf>Al<inf>2</inf>(OH)<inf>12</inf> <sup>2+</sup>] cluster, was obtained ab initio by direct methods in space group C2/m on the basis of electron diffraction data. Geometric and charge-balance considerations allowed to reach the whole structure model for the cyanotrichite-98 phase. The sulfate group and water molecule result to be statistically disordered over two possible positions, but keeping the average structure consistent with the C-centering symmetry, in agreement with ADT results.

Ventruti, G., Mugnaioli, E., Capitani, G., Scordari, F., Pinto, D., Lausi, A. (2015). A structural study of cyanotrichite from Dachang by conventional and automated electron diffraction. PHYSICS AND CHEMISTRY OF MINERALS, 42(8), 651-661 [10.1007/s00269-015-0751-z].

A structural study of cyanotrichite from Dachang by conventional and automated electron diffraction

CAPITANI, GIANCARLO;
2015

Abstract

The crystal structure of cyanotrichite, having general formula Cu4Al2(SO4)(OH)12·2H2O, from the Dachang deposit (China) was studied by means of conventional transmission electron microscopy, automated electron diffraction tomography (ADT) and synchrotron X-ray powder diffraction (XRPD). ADT revealed the presence of two different cyanotrichite-like phases. The same phases were also recognized in the XRPD pattern, allowing the perfect indexing of all peaks leading, after refinement to the following cell parameters: (1) a = 12.417(2) Å, b = 2.907(1) Å, c = 10.157(1) Å and β = 98.12(1); (2) a = 12.660(2) Å, b = 2.897(1) Å, c = 10.162(1) Å and β = 92.42(1)°. Only for the former phase, labeled cyanotrichite-98, a partial structure, corresponding to the [Cu4Al2(OH)12 2+] cluster, was obtained ab initio by direct methods in space group C2/m on the basis of electron diffraction data. Geometric and charge-balance considerations allowed to reach the whole structure model for the cyanotrichite-98 phase. The sulfate group and water molecule result to be statistically disordered over two possible positions, but keeping the average structure consistent with the C-centering symmetry, in agreement with ADT results.
Articolo in rivista - Articolo scientifico
Automated electron diffraction tomography (ADT); Cyanotrichite; Powder X-ray diffraction; Precession electron diffraction (PED);
Automated electron diffraction tomography (ADT); Cyanotrichite; Powder X-ray diffraction; Precession electron diffraction (PED)
English
2015
42
8
651
661
none
Ventruti, G., Mugnaioli, E., Capitani, G., Scordari, F., Pinto, D., Lausi, A. (2015). A structural study of cyanotrichite from Dachang by conventional and automated electron diffraction. PHYSICS AND CHEMISTRY OF MINERALS, 42(8), 651-661 [10.1007/s00269-015-0751-z].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/102516
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