Mössbauer-spectroscopic characterization of the stannides Sr₂Pd₂Sn and Eu₂Pd₂Sn

Abstract The Ca 2 Pd 2 Ge-type stannides Sr 2 Pd 2 Sn and Eu 2 Pd 2 Sn were synthesized by reaction of the elements in sealed tantalum ampoules in a high-frequency furnace and characterized by powder X-ray diffraction. The structure of Sr 2 Pd 2 Sn ( Fdd 2, a = 1063.95(5), b = 1623.22(9), c = 594.63(14) pm, w R 2 = 0.0472, 972 F 2 values and 26 variables) was refined from single-crystal X-ray diffractometer data. The striking structural motif features equidistant chains formed by the palladium atoms (304.7 pm Pd–Pd), which are interlinked by the tin atoms (266.9 and 268.7 pm Pd–Sn). Together, the palladium and tin atoms form a three-dimensional [Pd 2 Sn] δ – polyanionic network in which the strontium atoms reside in larger cavities. The divalent character of europium in Eu 2 Pd 2 Sn was manifested by 151 Eu Mössbauer spectroscopy. The isomer shift is δ = −9.48(1) mm s −1 at room temperature. The results of 119 Sn Mössbauer-spectroscopic experiments have confirmed the tin site determined by the single-crystal study, the isomer shifts being δ = 1.71(1) mm s −1 for Eu 2 Pd 2 Sn and δ = 1.73(1) mm s −1 for Sr 2 Pd 2 Sn. Sr 2 Pd 2 Sn is a Pauli paramagnet with a susceptibility of 2.2(1) × 10 −5 emu mol −1 at room temperature. Eu 2 Pd 2 Sn shows Curie-Weiss paramagnetism with an experimental magnetic moment of 7.85(1) µ B per Eu atom, confirming divalent europium. The europium magnetic moments order antiferromagnetically at T N = 14 K.