CuYb2Ge4O12, a new bidimensionally tunneled structure

Employing CuO as self flux crystals of CuYb2Ge4O12 have been grown for the first time, The crystal structure of CuYb2 Ge4O12 has been determined by single-crystal X-ray diffraction in the triclinic P (1) over bar (No. 2) space group to an R value of 6.1%, with a = 7.156(2) Angstrom, b = 7.937(3) Angstrom, c = 4.905(3) Angstrom, alpha = 86.63(3)degrees, beta = 102.41(4)degrees, gamma = 114.12(3)degrees, V = 248.2(2) Angstrom(3), Z = 1, and D-c = 5.97 gcm(-3). The novel tridimensional CuYb2Ge4O12 structure type can be conceived as formed by layers of (GeO4)(4) units of vertex-sharing GeO4 tetrahedra, chains of YbO7 polyhedra, and isolated CuO4 squares connecting (GeO4)(4) units, with channels or tunnels of size up to 4.08 Angstrom in the a and c directions. A comparison is made between the structure types of the title germanate and recently reported CuNd2Ge2O8. The temperature dependence from 350 to 1.8 K of the reciprocal de magnetic susceptibility for CuYb2Ge4O12 is shown and presents a deviation from linearity over the whole temperature range. The infrared spectrum between 1000 and 100 cm(-1) is given and related with those of comparable species. (C) 1996 academic Press, Inc.