The crystal structure of gustavite, PbAgBi3S6. Analysis of twinning and polytypism using the OD approach.
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The crystal structure of gustavite, PbAgBi3S6. Analysis of twinning and polytypism using the OD approach. / Makovicky, Emil; Topa, Dan.
In: European Journal of Mineralogy, Vol. 23, No. 4, 07.2011, p. 537-550.Research output: Contribution to journal › Journal article › Research › peer-review
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TY - JOUR
T1 - The crystal structure of gustavite, PbAgBi3S6. Analysis of twinning and polytypism using the OD approach.
AU - Makovicky, Emil
AU - Topa, Dan
PY - 2011/7
Y1 - 2011/7
N2 - The crystal structure of gustavite Pb1.06Ag0.95Bi2.80Sb0.20S5.99 from Rotgu¨lden, Lungau, Salzburg Land, Austria, was refined to R1 ¼ 2.76 % using single-crystal X-ray diffraction data. Refined unit-cell parameters are a 7.0567(14), b 19.6905(39), c 8.2219(16) A ° , b 106.961(3) , unit-cell volume 1092.7(2) A ° 3 and space group is P21/c. The structure contains a bicapped trigonal prismatic Pb site, a [001] string of Ag and Bi1 octahedral sites and a similar string of Bi2 and Bi3 coordination octahedra. Sb is concentrated in the Bi3 site whereas Bi1 and Ag contain a fraction (0.1–0.14 atom) of the opposite species; the latter is explained by a presence of twin lamellae or antiphase domains in the crystal. In accordance with its frequently observed twinning, gustavite is an OD (order-disorder) structure that can be described by zig-zag unit layers with layer symmetry P(2/n) 21/c 2/m and the interlayer symmetry elements {(22/n1,1/2) 21/n1/2,2 21/2/ a2}. An alternative OD description uses planar unit layers with the layer symmetry P(2/ b) 21/c 21/m and the interlayer elements 22/n1,–1/2 21/n1/2,2 21/2/a2. The former description adheres closely to the details of coordination of bismuth observed in the structure whereas the latter description is based on a more abstract structure model.
AB - The crystal structure of gustavite Pb1.06Ag0.95Bi2.80Sb0.20S5.99 from Rotgu¨lden, Lungau, Salzburg Land, Austria, was refined to R1 ¼ 2.76 % using single-crystal X-ray diffraction data. Refined unit-cell parameters are a 7.0567(14), b 19.6905(39), c 8.2219(16) A ° , b 106.961(3) , unit-cell volume 1092.7(2) A ° 3 and space group is P21/c. The structure contains a bicapped trigonal prismatic Pb site, a [001] string of Ag and Bi1 octahedral sites and a similar string of Bi2 and Bi3 coordination octahedra. Sb is concentrated in the Bi3 site whereas Bi1 and Ag contain a fraction (0.1–0.14 atom) of the opposite species; the latter is explained by a presence of twin lamellae or antiphase domains in the crystal. In accordance with its frequently observed twinning, gustavite is an OD (order-disorder) structure that can be described by zig-zag unit layers with layer symmetry P(2/n) 21/c 2/m and the interlayer symmetry elements {(22/n1,1/2) 21/n1/2,2 21/2/ a2}. An alternative OD description uses planar unit layers with the layer symmetry P(2/ b) 21/c 21/m and the interlayer elements 22/n1,–1/2 21/n1/2,2 21/2/a2. The former description adheres closely to the details of coordination of bismuth observed in the structure whereas the latter description is based on a more abstract structure model.
U2 - 10.1127/0935-1221/2011/0023-2114
DO - 10.1127/0935-1221/2011/0023-2114
M3 - Journal article
VL - 23
SP - 537
EP - 550
JO - European Journal of Mineralogy
JF - European Journal of Mineralogy
SN - 0935-1221
IS - 4
ER -
ID: 36091064