Syntheses, Crystal Structures, and Properties of EuRhIn, EuIr2, and EuIrSn2

Abstract

The title compounds were prepared from the elements by reactions in sealed tantalum tubes in a high-frequency furnace. Their structures were refined from single crystal X-ray diffractometer data: Pnma, a=744.4(1) pm, b=434.15(9) pm, c=845.5(1) pm, wR2=0.0433, 658 F2 values, 20 variables for EuRhIn, Fd3m, a=756.5(1) pm, wR2=0.0349, 94 F2 values, 5 variables for EuIr2, and Cmcm, a=434.78(3) pm, b=1124.0(1) pm, c=751.20(5) pm, wR2=0.0561, 565 F2 values, 16 variables for EuIrSn2. EuRhIn crystallizes with a TiNiSi type structure that consists of strongly puckered Rh3In3 hexagons. The europium atoms fill the channels within the three-dimensional [RhIn] polyanion. EuRhIn orders ferromagnetically at 22.0(5) K with a saturation magnetic moment of 6.7(1) μB/Eu at 4 K and 5.5 T. The divalent character of the europium atoms in EuRhIn was determined from temperature dependent susceptibility (7.9 μB/Eu in the high-temperature part) and 151Eu Mössbauer spectroscopic experiments. The latter show an isomer shift of δ=−8.30(2) mm/s at 78 K. At 4.2 K full magnetic hyperfine field splitting subjected to significant quadrupole splitting of ΔEQ=8 mm/s is observed. EuRhIn is a metallic conductor with a room temperature value of 58 μΩcm for the specific resistivity. The structure of the Laves phase EuIr2 is confirmed on the basis of single crystal X-ray data. The iridium atoms form a tetrahedral network with Ir–Ir distances of 268 pm. EuIrSn2 adopts a MgCuAl2 type structure that may be described as an iridium-filled variant of a distorted CaIn2-like sublattice of composition EuSn2. The tin atoms in the distorted and puckered hexagonal network have shorter (303 and 322 pm) and longer (343 pm) tin-tin contacts.