RE 13Pd25+x Zn28–x (RE = Y, Ho–Lu) – A 4 × 4 × 4 tungsten superstructure with short Pd/Zn dumbbells as structural motif

Abstract

Abstract The rare earth-based zinc compounds RE 13Pd25+x Zn28–x (RE = Y, Ho–Lu) were synthesized from the elements in sealed niobium ampoules with a maximum reaction temperature of 1470 K followed by different annealing sequences. The structures of all compounds were refined from single crystal X-ray diffraction data, indicating substantial Zn/Pd mixing on one 8c and one 24g zinc site. Exemplarily, the homogeneity range of the solid solution Yb13Pd25+x Zn28–x was manifested from samples of different starting compositions and five single crystal data sets. The RE 13Pd25+x Zn28–x structures are cubic, space group I4̅3m with lattice parameters ranging from 1295 to 1307 pm, as a function of the rare earth element and the Zn/Pd mixing. Hierarchically, one can derive the RE 13Pd25+x Zn28–x structures from the simple bcc packing. A group–subgroup scheme was developed for this new 4 × 4 × 4 tungsten superstructure which shows vacancy ordering and dumbbell formation. Temperature dependent magnetic susceptibility measurements show diamagnetism for a Lu13Pd29Zn24 sample and Curie–Weiss paramagnetism for Tm13Pd29Zn24 down to 3 K.