Yb3AuGe2In3: An Ordered Variant of the YbAuIn Structure Exhibiting Mixed-Valent Yb Behavior

Yb3AuGe2In3 was obtained as large single crystals in high yield from reactions run in liquid indium. Single crystal X-ray diffraction data show that Yb3AuGe2In3 is an ordered variant of YbAuIn with lattice constants, a = b = 7.3153(8) A and c = 4.4210(5) A, and space group P62m. The parent compound YbAuIn was also studied for comparison. YbAuIn crystallizes in the ZrNiAl structure type, hexagonal, P62m space group with lattice parameters a = b = 7.7127(11) A and c = 4.0294(8) A. In Yb3AuGe2In3, Ge substitutes for one of the two Au positions in the ternary compound Yb3Au3In3. The structure can be described as alternating [Ge2In3] and [Yb3Au] slabs that stack along the c-axis. The magnetic susceptibility data follow a modified Curie−Weiss law. The effective magnetic moment μeff of 0.52 μB/Yb atom was deduced from the Curie constant and Curie−Weiss constant of θp = −1.5 K indicating antiferromagnetic interactions in Yb3AuGe2In3. X-ray absorption near edge spectroscopy (XANES) measurements indicate intermed...