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

Single phase samples of the compounds Cu2CoSi(Ge,Sn)S4 and Cu2CoGe(Sn)Se4 were prepared. The crystal structures of these compounds were investigated using X-ray powder diffraction. The compounds Cu2CoSi(Ge,Sn)S4 and Cu2CoSnSe4 crystallize in the stannite structure (space group I<F>&4macr;</F>2m) with the lattice parameters: <F>a=0.52644(1) nm</F>, <F>c=1.03160(5) nm</F> (Cu2CoSiS4), <F>a=0.52957(1) nm</F>, <F>c=1.04709(5) nm</F> (Cu2CoGeS4), <F>a=0.53956(8) nm</F>, <F>c=1.0789(3) nm</F> (Cu2CoSnS4) and <F>a=0.56676(2) nm</F>, <F>c=1.13146(9) nm</F> (Cu2CoSnSe4). The atomic parameters were refined in the isotropic approximation (<F>RI=0.0770</F>, 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 <F>a=0.55858(6) nm</F>, <F>b=0.55560(6) nm</F>, <F>c=0.54935(5) nm</F> (<F>RI=0.0429</F>). [Copyright &y& Elsevier]