Crystal structures of the compounds Cu 2CoSi(Ge,Sn)S 4 and Cu 2CoGe(Sn)Se 4

Abstract

Single phase samples of the compounds Cu 2CoSi(Ge,Sn)S 4 and Cu 2CoGe(Sn)Se 4 were prepared. The crystal structures of these compounds were investigated using X-ray powder diffraction. The compounds Cu 2CoSi(Ge,Sn)S 4 and Cu 2CoSnSe 4 crystallize in the stannite structure (space group I 4 ̄ 2 m) with the lattice parameters: a=0.52644(1) nm , c=1.03160(5) nm (Cu 2CoSiS 4), a=0.52957(1) nm , c=1.04709(5) nm (Cu 2CoGeS 4), a=0.53956(8) nm , c=1.0789(3) nm (Cu 2CoSnS 4) and a=0.56676(2) nm , c=1.13146(9) nm (Cu 2CoSnSe 4). The atomic parameters were refined in the isotropic approximation ( R I=0.0770, 0.0736, 0.0638; and 0.0541 for Cu 2CoSiS 4, Cu 2CoGeS 4, Cu 2CoSnS 4 and Cu 2CoSnSe 4, respectively). The Cu 2CoGeSe 4 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 I=0.0429).