The stannides
RE2Au
3Sn
6 (
RE = La, Ce, Pr, Nd, Sm) were synthesized from the elements by arc-melting. Small single crystals were grown by annealing samples in sealed tantalum tubes in an induction furnace with a special annealing sequence. The polycrystalline phases were characterized through their X-ray powder diffraction pattern. The structures of Ce
2Au
3Sn
6, Pr
2Au
3Sn
6, and Nd
2Au
3Sn
6 were refined from single-crystal X-ray diffractometer data. The
RE2Au
3Sn
6 stannides crystallize with the orthorhombic La
2Zn
3Ge
6 type, space group
Cmcm. The basic structural building units are Au1@Sn
4 tetrahedra and Au2@Sn
5 square pyramids. These units are condensed to layers and the structure can be described by a simple stacking of tetrahedral and pyramidal layers with the rare earth cations in between. Temperature dependent susceptibility studies indicate that all rare earth atoms are in the trivalent oxidation state, as their effective magnetic moments match the expected values of the free
RE3+ ions. Pr
2Au
3Sn
6 and Nd
2Au
3Sn
6 exhibit antiferromagnetic ordering at
TN = 6.3(1) and 6.7(1) K. Investigations of the electrical resistivity of La
2Au
3Sn
6 and Ce
2Au
3Sn
6 confirmed that these compounds are metallic, for La
2Au
3Sn
6 a lower resistivity was observed, in line with the absence of screening unpaired electrons.
119Sn Mössbauer spectra for La
2Au
3Sn
6, Ce
2Au
3Sn
6, Pr
2Au
3Sn
6 and Nd
2Au
3Sn
6 show a complex superposition of three sub-spectra which can be differentiated through their distinctly different quadrupole splitting parameters. The isomer shifts (1.87 to 2.22 mm · s
–1) indicate significant
s electron density at the tin nuclei.
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