SYNTHESIS AND STRUCTURES OF THE QUATERNARY SULFIDES KGASNS4, KINGES4, AND KGAGES4

The new quaternary compounds KGaSnS4, KInGeS4, and KGaGeS4 have been synthesized by the reaction of K2S5 with elemental Ga or In, Sn or Ge, and S at 900°C. The crystal structures of the three compounds have been determined by single-crystal X-ray diffraction techniques. Crystal data: KGaSnS4-space group P1, Z = 4, a = 7.152(2), b = 7.847(2), and c = 15.163(3) Å, α = 83.78(2)°, β = 87.21(2)°, γ = 63.83(2)° (T = 153 K), R(F2) = 0.147 for 3068 observations and 130 variables, R(F) = 0.073 for 2432 observations having F2o > 3σ(F2o); KInGeS4-space group P1, Z = 4, a = 7.200(5), b = 7.739(5), and c = 15.037(10) Å, α = 91.83(3)°, β = 99.26(4)°, γ = 112.01(4)° (T = 294 K), R(F2) = 0.124 for 4832 observations and 131 variables, R(F) = 0.048 for 1956 observations having F2o > 3σ(F2o); KGaGeS4-space group P21 a, Z = 4, a = 6.853(2), b = 15.956(5), and c = 7.108(2) Å, β = 111.95(1)° (T = 115 K), R(F2) = 0.060 for 2235 observations and 65 variables, R(F) = 0.027 for 1925 observations having F2o > 3σ(F2o). While the three crystal structures differ, they show close similarities. All three structures are made up of layers of metal-centered tetrahedra separated by potassium ions. The main group metal atoms are disordered to varying degrees among the tetrahedra. In each structure the tetrahedra form corner-sharing chains along the a axis and these chains are connected by pairs of edge-sharing tetrahedra. The layers in KInGeS4 and KGaGeS4 have the same structure while that in KGaSnS4 is different, owing to the different ways the edge-sharing tetrahedral pairs connect the chains. All three compounds are poor conductors. © 1992.