Quaternary intermetallics RE2Pt3Ga4In (RE= Y, Gd-Tm) - intergrowth structures of NdRh2Sn4 and TiNiSi related stabs

摘要

The quaternary gallium-rich intermetallic phases RE2Pt3Ga4 In with RE=Y and Gd-Tm were synthesized by arc-melting of the elements and subsequent annealing. Small single crystals were obtained by high-frequency annealing of the samples in sealed tantalum ampoules. The polycrystalline samples were characterized through their X-ray powder patterns. The RE2Pt3Ga4 In phases crystallize with a site ordering variant of the orthorhombic Y2Rh3Sn5 type, space group Cmc2(1). The structures of Gd2Pt3Ga4In, Dy2Pt3Ga4.14In0.86, Er2Pt3Ga4.7In0.83 and Tm2Pt3Ga4.21In0.79 were refined from single-crystal X-ray diffraction data. The single crystals reveal small homogeneity ranges RE2Pt3Ga4 +/- xIn1 +/- x. The striking geometrical structural building units are slightly distorted trigonal prisms around the three crystallographically independent platinum atoms: Pt1@RE4Ga2, Pt2@RE2Ga4 and Pt3@RE2Ga2In2. Based on these prismatic building units, the RE2Pt3Ga4In structures can be described as intergrowth variants of TiNiSi and NdRh2Sn4 related structural slabs. Temperature dependent magnetic susceptibility studies of Gd2Pt3Ga4In and Tb 2 Pt3Ga4In show Curie-Weiss behavior and the experimental magnetic moments confirm stable trivalent gadolinium respectively terbium. Gd2Pt3Ga4In and Tb2Pt3Ga4In order antiferromagnetically at T-N = 15.8(1) and 26.0(1) K. Magnetization curves at 3 K show field-induced spin reorientations.