SITE OCCUPANCY WAVE AND UNPRECEDENTED INFINITE ZIGZAG (TE-2(2-))(N) CHAINS IN THE FLAT TE NETS OF THE NEW TERNARY RARE-EARTH TELLURIDE FAMILY ALN(3)TE(8)

The three isostructural compounds CsCe3Te8, RbCe3Te8, and KNd3Te8 were synthesized from the reaction of elemental copper and lanthanides in a molten alkali metal/polytelluride flux, They crystallize in the mono clinic space group P2(1)/a (No. 14) with a = 9.057(2) Angstrom, b = 12 .996(3) Angstrom, c = 14.840(3) Angstrom, beta = 98.74(2)degrees, V = 1726.4(7)Angstrom(3), and Z = 4 for CsCe3Te8; a = 9.051(2) Angstrom, b = 12.996(3) Angstrom, c = 14.376(3) Angstrom, beta = 98.87(2)degrees, V = 1670.8(7), Angstrom(3), and Z = 4 for RbCe3Te8; and a = 8.956(1) Angstrom, b = 12.836(2) Angstrom, c = 13.856(3) Angstrom, beta = 99.42 (1)degrees, V = 1571.3(3) Angstrom(3), and Z = 4 for KNd3Te8. The stru cture of all three compounds can be described as a defect NdTe3 type, consisting of an anionic Ln(3)Te(8)(-) layer that is charge balanced w ith A(+) cations, The anionic layer contains a square Te lattice net w ith an unprecedented ordered defect pattern site occupancy wave. Varia ble-temperature electrical conductivity and thermopower measurements a re reported. (C) 1998 Academic Press.