Mixed valency in Yb7Co4InGe12: A novel intermetallic compound stabilized in liquid indium

The quaternary compounds RE7Co4InGe12 (RE = Dy, Ho, Yb) were obtained from In flux reactions as thin silver needles. RE7Co4InGe12 crystallizes in the tetragonal P4/m space group under a new structure type which is characterized by columnar units forming three different types of channels with the RE atoms situated within these channels. Investigation of the Yb analog with magnetic susceptibility measurements, X-ray photoelectron spectroscopy (XPS) and X-ray absorption near edge spectroscopy (XANES) revealed that Yb7Co4InGe12 is a mixed-valence compound and that the relative Yb3+/Yb2+ ratio is slightly temperature-dependent. Additionally, resistivity measurements for Yb7Co4InGe12 exhibited negative magnetoresistance at low temperatures.