Structure refinements of REAuSn (RE = Sm, Gd, Tm)

Abstract

Well-shaped single crystals of the stannides REAuSn (RE = Sm, Gd, Tm) were obtained from arc-melted ingots. The samples were investigated on the basis of X-ray powder and single crystal data: NdPtSb type, P63mc, Z = 2, a = 467.3(1), c = 748.9(2) pm, wR2 = 0.0468, BASF = 0.273(14), 273 F2 values, 12 variables for SmAuSn, a = 465.14(9), c = 742.4(1) pm, wR2 = 0.0686, 265 F2 values, 11 variables for GdAuSn, and MgAgAs type, F43m, Z = 4, a = 658.54(9) pm, wR2 = 0.0384, 120 F2 values, 5 variables for TmAuSn. The [AuSn] networks in SmAuSn and GdAuSn are two-dimensional with intralayer Au-Sn distances of 278 and 277 pm in the slightly puckered Au 3Sn3 hexagons, respectively. The interlayer Au-Sn distances of 308 and 302 pm are much longer. TmAuSn has a network of corner-sharing AuSn4/4 tetrahedra with Au-Sn distances of 285 pm. The thulium atoms fill octahedral sites formed by the tin atoms. The crystal chemistry of these REAuSn stannides is briefly discussed. © 2006 Verlag der Zeitschrift für Naturforschung.