New ternary lanthanide transition-metal tellurides: Dy6MTe2, M = Fe, Co, Ni

The isotypic title compounds together with R6CoTe2 for R = Y, La have been synthesized in Ta containers at high temperature and their lattice paramete rs refined from Guinier X-ray powder diffraction data. The structure of thi s family has been detailed in space group P (6) over bar 2m (Z = 1) by sing le-crystal X-ray diffraction data for the case of Dy6FeTe2 (a = 8.236(3) An gstrom, c = 4.0107(2) Angstrom, 23 degreesC, R(F)/R-w = 3.6/3.8%). The over all structure is of the Zr6CoAl2 type, an ordered derivative of the Fe2P ty pe. Extended Huckel calculations help to interpret the stabilization of thi s structure by iron or electron-richer elements. Strong Dy-Fe interactions in more to chains are a noteworthy feature. (C) 2000 Academic Press.