✍ Scribed by Rolf-Dieter Hoffmann; Rainer Pöttgen
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Single phase SrPtIn, Sr 2 Pt 3 In 4 and Ca 2 Au 3 In 4 were prepared by high-frequency melting of the elements in water-cooled glassy carbon crucibles. X-ray diffraction of powders and single crystals yielded Pnma, oP12, a = 758.57(9) pm, b = 451.52(6) pm, c = 846.0(2) pm, wR2 = 0.0937, 467 F 2 values, 20 variables for SrPtIn, P62m, hP36, a = 1465.9(2) pm, c = 448.24(6) pm, wR2 = 0.0722, 1059 F 2 values, 44 variables for Sr 2 Pt 3 In 4 and Pnma, oP36, a = 1463.6(4) pm, b = 443.23(9) pm, c = 1272.3(2) pm, wR2 = 0.0694, 1344 F 2 values, 56 variables for Ca 2 Au 3 In 4 . SrPtIn adopts the TiNiSi type structure. The indium atoms have a distorted tetrahedral platinum coordination. These InPt 4/4 tetrahedra are edge-and corner-shared, forming a three-dimensional [PtIn] polyanion in which the strontium atoms are embedded. Sr 2 Pt 3 In 4 crystallizes with the Hf 2 Co 4 P 3 type structure with the more electronegative platinum atoms occupying the phosphorus sites while the indium atoms are located on the cobalt positions. Ca 2 Au 3 In 4 is a new site occupancy variant of the YCo 5 P 3 type. Gold atoms occupy the phosphorus sites and indium the cobalt sites, but one cobalt site is occupied by calcium atoms leading to the composition Ca 2 Au 3 In 4 . Common geometrical motifs of both structures are condensed, platinum(gold)-centered trigonal prisms formed by the alkaline earth and indium atoms. The platinum (gold) and indium atoms form complex three-dimensional [Pt 3 In 4 ] and [Au 3 In 4 ] polyanions, respectively. The alkaline earth cations are located in distorted hexagonal tubes.
📜 SIMILAR VOLUMES
Investigations of three systems lead to the stabilization of new pseudo-ternary RT(T' 0.5 X 1.5 ) and R 3 T 2 T' 2 X 4 compounds with TbFeSi 2 and U 3 Ni 4 Si 4 -type structures. These are characterized by a stacking of RT 2 X 2 (BaAl 4 -type) and RT'X (AlB 2 -type) layers. Therefore, the new alloys