| People | Locations | Statistics |
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| Naji, M. |
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| Motta, Antonella |
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| Aletan, Dirar |
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| Mohamed, Tarek |
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| Ertürk, Emre |
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| Taccardi, Nicola |
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| Kononenko, Denys |
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| Petrov, R. H. | Madrid |
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| Alshaaer, Mazen | Brussels |
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| Bih, L. |
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| Casati, R. |
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| Muller, Hermance |
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| Kočí, Jan | Prague |
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| Šuljagić, Marija |
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| Kalteremidou, Kalliopi-Artemi | Brussels |
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| Azam, Siraj |
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| Ospanova, Alyiya |
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| Blanpain, Bart |
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| Ali, M. A. |
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| Popa, V. |
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| Rančić, M. |
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| Ollier, Nadège |
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| Azevedo, Nuno Monteiro |
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| Landes, Michael |
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| Rignanese, Gian-Marco |
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Spratt, John
Natural History Museum
in Cooperation with on an Cooperation-Score of 37%
Topics
Publications (11/11 displayed)
- 2022Polytypism in mcalpineite: a study of natural and synthetic Cu3TeO6citations
- 2021Kernowite, Cu<sub>2</sub>Fe(AsO<sub>4</sub>)(OH)<sub>4</sub>⋅4H<sub>2</sub>O, the Fe<sup>3+</sup>-analogue of liroconite from Cornwall, UKcitations
- 2021Oscillatory- and sector-zoned pyrochlore from carbonatites of the Kerimasi volcano, Gregory rift, Tanzaniacitations
- 2021Elucidating the natural–synthetic mismatch of Pb2+Te4+O3: The redefinition of fairbankite to Pb122+(Te4+O3)11(SO4)citations
- 2021Native tungsten from the Bol'shaya Pol'ya river valley and Mt Neroyka, Russia
- 2021Wildcatite, CaFe3+Te6+O5(OH), the second new tellurate mineral from the Detroit district, Juab County, Utahcitations
- 2021Hybridization of Alkali Basaltic Magmas: a Case Study of the Ogol Lavas from the Laetoli Area, Crater Highlands (Tanzania)citations
- 2019Dokuchaevite, Cu<sub>8</sub>O<sub>2</sub>(VO<sub>4</sub>)<sub>3</sub>Cl<sub>3</sub>, a new mineral with remarkably diverse Cu<sup>2+</sup> mixed-ligand coordination environmentscitations
- 2019The crystal structures of the mixed-valence tellurium oxysalts tlapallite, (Ca,Pb)<sub>3</sub>CaCu<sub>6</sub>[Te<sup>4+</sup><sub>3</sub>Te<sup>6+</sup>O<sub>12</sub>]<sub>2</sub>(Te<sup>4+</sup>O<sub>3</sub>)<sub>2</sub>(SO<sub>4</sub>)<sub>2</sub>·3H<sub>2</sub>O, and carlfriesite, CaTe<sup>4+</sup><sub>2</sub>Te<sup>6+</sup>O<sub>8</sub>citations
- 2015Barrydawsonite-(Y), Na<sub>1.5</sub>CaY<sub>0.5</sub>Si<sub>3</sub>O<sub>9</sub>H: a new pyroxenoid of the pectolite–serandite groupcitations
- 2013Diegogattaite, Na<sub>2</sub>CaCu<sub>2</sub>Si<sub>8</sub>O<sub>2</sub>0·H<sub>2</sub>O: a new nanoporous copper sheet silicate from Wessels Mine, Kalahari Manganese Fields, Republic of South Africacitations
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article
Polytypism in mcalpineite: a study of natural and synthetic Cu3TeO6
Abstract
<jats:p>Synthetic and naturally occurring forms of tricopper orthotellurate, Cu<jats:sup>II</jats:sup><jats:sub>3</jats:sub>Te<jats:sup>VI</jats:sup>O<jats:sub>6</jats:sub> (the mineral mcalpineite) have been investigated by 3D electron diffraction (3D ED), X-ray powder diffraction (XRPD), Raman and infrared (IR) spectroscopic measurements. As a result of the diffraction analyses, Cu<jats:sup>II</jats:sup><jats:sub>3</jats:sub>Te<jats:sup>VI</jats:sup>O<jats:sub>6</jats:sub> is shown to occur in two polytypes. The higher-symmetric Cu<jats:sup>II</jats:sup><jats:sub>3</jats:sub>Te<jats:sup>VI</jats:sup>O<jats:sub>6</jats:sub>-1<jats:italic>C</jats:italic> polytype is cubic, space group <jats:italic>Ia</jats:italic><jats:overline>3</jats:overline>, with <jats:italic>a</jats:italic> = 9.537 (1) Å and <jats:italic>V</jats:italic> = 867.4 (3) Å<jats:sup>3</jats:sup> as reported in previous studies. The 1<jats:italic>C</jats:italic> polytype is a well characterized structure consisting of alternating layers of Cu<jats:sup>II</jats:sup>O<jats:sub>6</jats:sub> octahedra and both Cu<jats:sup>II</jats:sup>O<jats:sub>6</jats:sub> and Te<jats:sup>VI</jats:sup>O<jats:sub>6</jats:sub> octahedra in a patchwork arrangement. The structure of the lower-symmetric orthorhombic Cu<jats:sup>II</jats:sup><jats:sub>3</jats:sub>Te<jats:sup>VI</jats:sup>O<jats:sub>6</jats:sub>-2<jats:italic>O</jats:italic> polytype was determined for the first time in this study by 3D ED and verified by Rietveld refinement. The 2<jats:italic>O</jats:italic> polytype crystallizes in space group <jats:italic>Pcca</jats:italic>, with <jats:italic>a</jats:italic> = 9.745 (3) Å, <jats:italic>b</jats:italic> = 9.749 (2) Å, <jats:italic>c</jats:italic> = 9.771 (2) Å and <jats:italic>V</jats:italic> = 928.3 (4) Å<jats:sup>3</jats:sup>. High-precision XRPD data were also collected on Cu<jats:sup>II</jats:sup><jats:sub>3</jats:sub>Te<jats:sup>VI</jats:sup>O<jats:sub>6</jats:sub>-2<jats:italic>O</jats:italic> to verify the lower-symmetric structure by performing a Rietveld refinement. The resultant structure is identical to that determined by 3D ED, with unit-cell parameters <jats:italic>a</jats:italic> = 9.56157 (19) Å, <jats:italic>b</jats:italic> = 9.55853 (11) Å, <jats:italic>c</jats:italic> = 9.62891 (15) Å and <jats:italic>V</jats:italic> = 880.03 (2) Å<jats:sup>3</jats:sup>. The lower symmetry of the 2<jats:italic>O</jats:italic> polytype is a consequence of a different cation ordering arrangement, which involves the movement of every second Cu<jats:sup>II</jats:sup>O<jats:sub>6</jats:sub> and Te<jats:sup>VI</jats:sup>O<jats:sub>6</jats:sub> octahedral layer by (1/4, 1/4, 0), leading to an offset of Te<jats:sup>VI</jats:sup>O<jats:sub>6</jats:sub> and Cu<jats:sup>II</jats:sup>O<jats:sub>6</jats:sub> octahedra in every second layer giving an <jats:italic>ABAB</jats:italic>* stacking arrangement. Syntheses of Cu<jats:sup>II</jats:sup><jats:sub>3</jats:sub>Te<jats:sup>VI</jats:sup>O<jats:sub>6</jats:sub> showed that low-temperature (473 K) hydrothermal conditions generally produce the 2<jats:italic>O</jats:italic> polytype. XRPD measurements in combination with Raman spectroscopic analysis showed that most natural mcalpineite is the orthorhombic 2<jats:italic>O</jats:italic> polytype. Both XRPD and Raman spectroscopy measurements may be used to differentiate between the two polytypes of Cu<jats:sup>II</jats:sup><jats:sub>3</jats:sub>Te<jats:sup>VI</jats:sup>O<jats:sub>6</jats:sub>. In Raman spectroscopy, Cu<jats:sup>II</jats:sup><jats:sub>3</jats:sub>Te<jats:sup>VI</jats:sup>O<jats:sub>6</jats:sub>-1<jats:italic>C</jats:italic> has a single strong band around 730 cm<jats:sup>−1</jats:sup>, whereas Cu<jats:sup>II</jats:sup><jats:sub>3</jats:sub>Te<jats:sup>VI</jats:sup>O<jats:sub>6</jats:sub>-2<jats:italic>O</jats:italic> shows a broad double maximum with bands centred around 692 and 742 cm<jats:sup>−1</jats:sup>.</jats:p>