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Substitution of indium for chromium in TlIn 5 − x Cr x Se 8 : crystal structure of TlIn 4.811(5) Cr 0.189(5) Se 8

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ABSTRACT

The new thallium penta­(indium/chromium) octa­selenide, TlIn4.811(5)Cr0.189(5)Se8, has been synthesized by solid-state reaction. It crystallizes isotypically with TlIn5Se8 in the space group C2/m. Although the two Tl positions are disordered and only partially occupied, no Tl deficiency was observed. The insertion of chromium in the structure has been confirmed by EDS analysis. Chromium substitutes indium exclusively at one of three In sites, viz. at one of the positions with site symmetry 2/m (Wyckoff position 2a). In the crystal structure, edge-sharing InSe6 octa­hedra, and (In,Cr)Se6 octa­hedra and InSe4 tetra­hedra make up two types of columns that are linked into a framework in which two different types of channels parallel to [010] are present. The Tl atoms are located in the larger of the channels, whereas the other, smaller channel remains unoccupied.

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The crystal structure of TlIn4.811(5)Cr0.189(5)Se8. (a) Representation by atoms displayed with displacement ellipsoids at the 50% probability level; (b) polyhedral representation.
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fig1: The crystal structure of TlIn4.811(5)Cr0.189(5)Se8. (a) Representation by atoms displayed with displacement ellipsoids at the 50% probability level; (b) polyhedral representation.

Mentions: The composition of the crystals as determined from the refinement is in good agreement with the EDS analysis. The refined structure is represented in Fig. 1 ▸, both as individual atoms and in a polyhedral representation. All atoms in the asymmetric unit (two Tl, one mixed-occupied In/Cr, two In and four Se sites) are located on special positions. Except Tl2 and mixed-occupied (In1/Cr) on positions with site symmetry 2/m (Wyckoff positions 2d and 2a, respectively), all other atoms are located on a mirror plane (4i).


Substitution of indium for chromium in TlIn 5 − x Cr x Se 8 : crystal structure of TlIn 4.811(5) Cr 0.189(5) Se 8
The crystal structure of TlIn4.811(5)Cr0.189(5)Se8. (a) Representation by atoms displayed with displacement ellipsoids at the 50% probability level; (b) polyhedral representation.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5382607&req=5

fig1: The crystal structure of TlIn4.811(5)Cr0.189(5)Se8. (a) Representation by atoms displayed with displacement ellipsoids at the 50% probability level; (b) polyhedral representation.
Mentions: The composition of the crystals as determined from the refinement is in good agreement with the EDS analysis. The refined structure is represented in Fig. 1 ▸, both as individual atoms and in a polyhedral representation. All atoms in the asymmetric unit (two Tl, one mixed-occupied In/Cr, two In and four Se sites) are located on special positions. Except Tl2 and mixed-occupied (In1/Cr) on positions with site symmetry 2/m (Wyckoff positions 2d and 2a, respectively), all other atoms are located on a mirror plane (4i).

View Article: PubMed Central - HTML - PubMed

ABSTRACT

The new thallium penta­(indium/chromium) octa­selenide, TlIn4.811(5)Cr0.189(5)Se8, has been synthesized by solid-state reaction. It crystallizes isotypically with TlIn5Se8 in the space group C2/m. Although the two Tl positions are disordered and only partially occupied, no Tl deficiency was observed. The insertion of chromium in the structure has been confirmed by EDS analysis. Chromium substitutes indium exclusively at one of three In sites, viz. at one of the positions with site symmetry 2/m (Wyckoff position 2a). In the crystal structure, edge-sharing InSe6 octa­hedra, and (In,Cr)Se6 octa­hedra and InSe4 tetra­hedra make up two types of columns that are linked into a framework in which two different types of channels parallel to [010] are present. The Tl atoms are located in the larger of the channels, whereas the other, smaller channel remains unoccupied.

No MeSH data available.