Twinnite, Pb0.8Tl0.1Sb1.3As0.8S4, the OD character and the question of its polytypism
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Dan Topa
Abstract
The electron-microprobe analyses of the studied twinnite material from Jas Roux, France, show a uniform chemical composition Pb0.80Tl0.05Sb1.31As0.80S4.04. Twinnite is monoclinic; the space group is P21/n. Lattice parameters obtained from single-crystal diffractometer data are a = 7.997(2) Å, b = 19.517(5) Å, c = 8.634(2) Å, and β = equal to 91.061(4)°. The structure of twinnite contains two distinct Pb sites, two Sb positions, two mixed-occupancy (As,Sb) positions and eight anions. The short (Sb,As)—S bonds are arranged into crankshaft chains. Twinnite is a N = 3 member of the sartorite homologous series. It is related to guettardite which has different symmetry and a substantially different Sb : As ratio. These two compounds are configurational polytypes, with unit OD layers having layer group symmetry P21(n)m and P-1 in terms of twinnite lattice.
© by Oldenbourg Wissenschaftsverlag, München, Germany
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Artikel in diesem Heft
- Friedrich Liebau (1926–2011) Memorial
- On the symmetry and atomic ordering in (OH,F)-rich spessartine: towards a new hydrogarnet end-member
- Structural and 57Fe Mössbauer spectroscopic characterization of the synthetic NaFeSi2O6 (aegirine) – CaMgSi2O6 (diopside) solid solution series
- A neutron/X-Ray diffraction, IR, and 1H/29Si NMR Spectroscopic investigation of armenite: behavior of extra framework Ca cations and H2O molecules in microporous silicates
- RUB-55, a new hydrous layer silicate with silicate layers known as motives of the sodalite and octadecasil frameworks: Synthesis and crystal structure
- Crystal structure and morphology of fully hydrated zeolite Na-A
- A new borosilicate feldspar, KBSi3O8: synthesis, crystal structure and thermal behavior
- The crystal structure of aklimaite, Ca4[Si2O5(OH)2](OH)4 · 5 H2O
- The [9]-coordinated X site in the crystal structure of tourmaline-group minerals
- Crystal structure of 2M and 1A polytypes of balangeroite
- Twinnite, Pb0.8Tl0.1Sb1.3As0.8S4, the OD character and the question of its polytypism
- The new oxosilicate NaTbSi2O6: A comparison of its A- and D-type structure
- K2Ba5Si12O30 – a member of a homologous series among layered potassium barium silicates
- Synthesis and structures of two open-framework manganese phosphate-silicates
- Glass structural studies for borosilicates of the KBSi2O6—RbBSi2O6 system from X-ray diffraction data
