Details

Autor(en) / Beteiligte

• Pinto, Daniela
• Garavelli, Anna
• Bindi, Luca

Titel

Fluorite-related one-dimensional units in natural bismuth oxysulfates: the crystal structures of Bi 14 O 16 (SO 4 ) 5 and Bi 30 O 33 (SO 4 ) 9 (AsO 4 ) 2

Ist Teil von

• Acta crystallographica Section B, Structural science, crystal engineering and materials, 2015-10, Vol.71 (5), p.514-523

Erscheinungsjahr

2015

Quelle

Wiley Blackwell Single Titles

Beschreibungen/Notizen

• The crystal structures of two new natural Bi oxysulfates with the formula Bi 14 O 16 (SO 4 ) 5 [labelled new phase I ; monoclinic, space group C 2, a = 21.658 (4), b = 5.6648 (9), c = 15.092 (3) Å, β = 119.433 (11)° and Z = 2] and Bi 30 O 33 (SO 4 ) 9 (AsO 4 ) 2 [labelled new phase II ; triclinic, space group P 1, a = 5.670 (3), b = 13.9408 (9), c = 22.7908 (18) Å, α = 80.903 (5), β = 82.854 (14), γ = 78.27 (2)° and Z = 1] from the high-temperature fumarole deposit of the La Fossa crater at Vulcano (Aeolian Islands, Italy) are reported. The structures are built up by a combination of fluorite-related Bi—O units and isolated (SO 4 ) 2− tetrahedra ( new phase I ) or both (SO 4 ) 2− and (AsO 4 ) 3− tetrahedra ( new phase II ). Owing to the effect of stereoactive lone pairs of Bi 3+ , Bi—O units in both the structures can be suitably described in terms of oxo-centered OBi 4 tetrahedra. The structure of Bi 14 O 16 (SO 4 ) 5 is based upon one-dimensional [O 16 Bi 14 ] 10+ ribbons formed by six chains of edge-sharing OBi 4 tetrahedra extending along [010]. In the structure of Bi 30 O 33 (SO 4 ) 9 (AsO 4 ) 2 the same ribbon type coexists with another one-dimensional ribbon formed by seven chains of edge-sharing OBi 4 tetrahedra and with the composition [O 17 Bi 16 ] 14+ . Ribbons of the same type are joined by (SO 4 ) 2− and (AsO 4 ) 3− tetrahedra along [010] – if a reduced triclinic unit-cell setting is considered – so forming two different (001) slabs which alternate to each other along [001] and are joined by additional (SO 4 ) 2− tetrahedra. New phase I represents the natural analogues of synthetic Bi 14 O 16 (SO 4 ) 5 , but with an ordered structure model.