Structures cristallines de Zr 6Cu 8Si 12 et Hf 2CuGe 4 et caractérisation d'une famille de composés semimétalliques “pseudolamellaires” de formule ZrSi 2Cu x où x = 0,5, 1 et 1,33

Abstract

The structures of Zr 6Cu 8Si 12 and Hf 2CuGe 4 compounds were determined. Zr 6Cu 8Si 12 was studied by single-crystal X-ray diffraction analysis. The structure is of a new type (space group, I4/ mmm): Z = 1, a = 3.738(2) A ̊ , c = 28.223(8) A ̊ , D X = 5.86 Mg m −3, μ( Ag Kα) = 19.58 mm −1 and F(000) = 640. The final weighted R value was 0.074 for 404 reflections. Hf 2CuGe 4 was studied by powder X-ray diffraction analysis (Cu Kα radiation; space group, Cmcm): Z = 4, a = 3.758(1) A ̊ , b = 32.94(1) A ̊ , c = 3.749(1) A ̊ and R = 0.10 for 30 reflections. Hf 2CuGe 4 is isostructural with Zr 2CuGe 4, Hf 2CuSi 4 and Zr 2CuSi 4. The new structures are closely related to the ZrSi 2 and ZrCuSiAs structure types. Zr 6Cu 8Si 12 and Zr 2CuSi 4 complete a structural family with the formula ZrSi 2Cu x ( x = 0.5, 1 and 1.33) of “pseudolamellar” semimetallic compounds characterized by the intercalation of copper atom planes in the ZrSi 2 structure.