IMA 2017-C = Crystal structure of cesbronite: a novel sheet tellurate topology - formula revised

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Marco E. Ciriotti
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Iscritto il: ven 25 giu, 2004 11:31
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IMA 2017-C = Crystal structure of cesbronite: a novel sheet tellurate topology - formula revised

Messaggio da Marco E. Ciriotti » gio 23 nov, 2017 11:08

Prossima pubblicazione.

Referenza:
▪ Missen, O.P., Mills, S.J., Welch, M.D., Spratt, J., Rumsey, M.S., Birch, W.D., Brugger, J. (2018): The crystal structure of cesbronite, Cu3TeO4(OH)4: a novel sheet tellurate topology. Acta Crystallographica, B74, (in press).

Synopsis:
The novel crystal structure of cesbronite has been determined. It is composed of corrugated sheets of edge-sharing CuO6 and (Cu0.5Te0.5)O6 octahedra and shows well defined ordering of Cu and Te.

NdR: Revisione della formula.
Marco E. Ciriotti

«Things are interesting only in so far as they relate themselves to other things»

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Marco E. Ciriotti
Messaggi: 24572
Iscritto il: ven 25 giu, 2004 11:31
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Re: IMA 2017-C = Crystal structure of cesbronite: a novel sheet tellurate topology - formula revised

Messaggio da Marco E. Ciriotti » mer 31 gen, 2018 18:20

Pubblicazione effettuata.

Referenza:
▪ Missen, O.P., Mills, S.J., Welch, M.D., Spratt, J., Rumsey, M.S., Birch, W.D., Brugger, J. (2018): The crystal structure of cesbronite, Cu3TeO4(OH)4: a novel sheet tellurate topology. Acta Crystallographica, B74, 24-31.
Marco E. Ciriotti

«Things are interesting only in so far as they relate themselves to other things»

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Marco E. Ciriotti
Messaggi: 24572
Iscritto il: ven 25 giu, 2004 11:31
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IMA 2017-C = Crystal structure of cesbronite: a novel sheet tellurate topology - formula revised

Messaggio da Marco E. Ciriotti » ven 02 feb, 2018 9:22

Referenza:
▪ Missen, O.P., Mills, S.J., Welch, M.D., Spratt, J., Rumsey, M.S., Birch, W.D., Brugger, J. (2018): The crystal structure of cesbronite, Cu3TeO4(OH)4: a novel sheet tellurate topology. Acta Crystallographica, B74, 24-31.

Abstract:
The crystal structure of cesbronite has been determined using single-crystal X-ray diffraction and supported by electron-microprobe analysis, powder diffraction and Raman spectroscopy. Cesbronite is orthorhombic, space group Cmcm, with a = 2.93172(16), b = 11.8414(6), c = 8.6047(4) A˚ and V = 298.72 (3) A˚3. The chemical formula of cesbronite has been revised to CuII3TeVIO4(OH)4 from CuII5(TeIVO3)2(OH)62H2O. This change has been accepted by the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association, Proposal 17-C. The previously reported oxidation state of tellurium has been shown to be incorrect; the crystal structure, bond valence studies and charge balance clearly show tellurium to be hexavalent. The crystal structure of cesbronite is formed from corrugated sheets of edge-sharing CuO6 and (Cu0.5Te0.5)O6 octahedra. The structure determined here is an average structure that has underlying ordering of Cu and Te at one of the two metal sites, designated as M, which has an occupancy Cu0.5Te0.5. This averaging probably arises from an absence of correlation between adjacent polyhedral sheets, as there are two different hydrogen-bonding configurations linking sheets that are related by a 1/2a offset. Randomised stacking of these two configurations results in the superposition of Cu and Te and leads to the Cu0.5Te0.5 occupancy of the M site in the average structure. Bond-valence analysis is used to choose the most probable Cu/Te ordering scheme and also to identify protonation sites (OH). The chosen ordering scheme and its associated OH sites are shown to be consistent with the revised chemical formula.
Marco E. Ciriotti

«Things are interesting only in so far as they relate themselves to other things»

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Marco E. Ciriotti
Messaggi: 24572
Iscritto il: ven 25 giu, 2004 11:31
Località: via San Pietro, 55 I-10073 Devesi/Cirié TO - Italy
Contatta:

Re: IMA 2017-C = Crystal structure of cesbronite: a novel sheet tellurate topology - formula revised

Messaggio da Marco E. Ciriotti » ven 02 feb, 2018 10:05

La formula della xocomecatlite quasi certamente è diversa da quella che trovate oggi riportata in tutti i database e sul web (uguale a quella ora rivista della cesbronite).
Una formula più corretta potrebbe essere Cu2+3Te6+O6·nH2O (n ≤ 1). Diversi anche i dati di cella che - provvisoriamente - possono essere valori non troppo dissimili dai seguenti: tric P1 o P-1 7.33 13.04 14.17 82.6 83.9 90.1 1 1335

Un lavoro simile a quello ora pubblicato è in corso (anzi è già stato presentato per la pubblicazione) sulla eztlite.
Marco E. Ciriotti

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