Twinnite, Pb₀₈Tl_0.1Sb_1.3As_0.8S₄, the OD character and the question of its polytypism

TY - JOUR

T1 - Twinnite, Pb08Tl0.1Sb1.3As0.8S4, the OD character and the question of its polytypism

AU - Topa, Dan

AU - Makovicky, Emil

PY - 2012

Y1 - 2012

N2 - 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 P1 in terms of twinnite lattice.

AB - 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 P1 in terms of twinnite lattice.

U2 - 10.1524/zkri.2012.1491

DO - 10.1524/zkri.2012.1491

M3 - Journal article

SN - 2194-4946

VL - 227

SP - 468

EP - 475

JO - Zeitschfrift fur Kristallographie

JF - Zeitschfrift fur Kristallographie

IS - In memoriam Professor Friedrich Liebau, Part I

ER -