Crystal structure of synthetic Pb4.32Sb3.68S8.68Cl2.32 A chlorine-bearing alternative to Pb4Sb4S11
Kostov-Kytin, Vladislav V.; Petrova, Rossitza; Maciček, Josef
European Journal of Mineralogy Volume 9 Number 6 (1997), p. 1191 - 1198
published: Dec 2, 1997
manuscript accepted: May 16, 1997
manuscript received: Apr 29, 1997
ArtNo. ESP147050906004, Price: 29.00 €
Abstract A new synthetic chlorine sulphosalt, Pb4.32Sb3.68S8.6sCl2.32, was prepared at 500 °C by gas-transport reaction. Microprobe analyses give: Pb - 50.7, Sb - 27.3, S - 17.0, Cl - 4.5 wt%; total 99.5 wt%. An X-ray single-crystal investigation including site-occupancy refinement and application of the bond-valence method, shows that the chlorine sulphosalt is isopointal to Pb4Sb4S11. Crystal data: space group Pbam, a = 15.04(4), b = 15.51(3), c = 4.09(1) Å, V = 954.1(7) Å3, Z = 2, F.W. = 1675.24, Dx = 5.83 g.cm-3, and R = 0.039 for 1012 reflections with I>3σ (I). The special position 0, 0, 1/2 is recognized as being entirely occupied by chlorine. Other chlorine atoms partially substitute on specific sulphur positions, in connection with mixed (Pb, Sb) sites according to the heterovalent substitution scheme Pb2+ + Cl- → Sb3+ + S2-. It is possible that the planar PD4CI group plays a key structural-determining role in the formation of high chlorine-bearing lead-antimony sulphosalts.