Crystal structures of the compounds Cu2CoSi(Ge,Sn)S4 and Cu2CoGe(Sn)Se4

Single phase samples of the compounds Cu2CoSi(Ge,Sn)S-4 and Cu2CoGe(Sn)Se-4 were prepared. The crystal structures of these compounds were investigated using X-ray powder diffraction. The compounds Cu2CoSi(Ge,Sn)S-4 and Cu2CoSnSe4 crystallize in the stannite structure (space group I42m) with the lattice parameters: a = 0.52644(1) nm, c = 1.03160(5) nm (Cu2CoSiS4), a 0.52957(1) nm, c = 1.04709(5) nm (Cu2CoGeS4), a = 0.53956(8) nm, c = 1.0799(3) nm (Cu2CoSnS4) and a = 0.56676(2) nm, c = 1.13146(9) nm (Cu2CoSnSe4). The atomic parameters were refined in the isotropic approximation (R-1 = 0.0770, 0.0736, 0.0638; and 0.0541 for Cu2CoSiS4, Cu2CoGeS4, Cu2CoSnS4 and Cu2CoSnSe4, respectively). The Cu2CoGeSe4 compound crystallizes in an orthorhombic unit cell (space group F222) with the lattice parameters a = 0.55858(6) nm, b = 0.55560(6) nm, c = 0.54935(5) nm (R-1 = 0.0429). (C) 2004 Elsevier B.V. All rights reserved.