Crystal structure of Dy₁₁Ge_4.33In_5.67 and Tm₁₁Ge₄In₆ from X-ray single-crystal and powder data

Abstract

Single crystals of Dy11Ge4.33In5.67 were grown from a sample of the starting composition Dy55Ge20In25 by arc-melting and subsequent annealing. Dy11Ge4.33In5.67 crystallizes with the Sm11Ge4In6-type structure, space group I4/mmm, which was refined from single-crystal X-ray diffractometer data: a = 11.4329(16), c = 16.168(3) Å, wR2 = 0.0341, 927 F 2 values and 42 refined parameters. The isotypic compound Tm11Ge4In6 was characterized by X-ray powder diffraction: a = 11.262(2), c = 15.979(3) Å, R Bragg = 3.53%. The Sm11Ge4In6-type structure is a coloring variant of the Ho11Ge10 type, realized through germanium-indium ordering. The p-element substructure has four crystallographically independent sites: isolated germanium atoms (Ge4− Zintl anions), In4 squares and In/Ge–In/Ge dumb-bells with pronounced Ge/In mixing.