New intermetallics YbAu₂In₄ and Yb₂Au₃In₅

Abstract

The intermetallic compounds YbAu₂In₄ and Yb₂Au₃In₅ were obtained as single crystals in high yield from reactions run in liquid indium. Single crystal X-ray diffraction data of YbAu₂In₄ showed that it crystallizes as a new structure type in the monoclinic space group P2₁/m and lattice constants a = 7.6536(19) Å, b = 4.5424(11) Å, c = 9.591(2) Å and β = 107.838(4)°. The YbAu₂In₄ compound is composed of a complex [Au₂In₄]³⁻ polyanionic network in which the rare-earth ions are embedded. Yb₂Au₃In₅ crystallizes in the polar space group Cmc2₁ with the Y₂Rh₃Sn₅ type structure and lattice constants a = 4.5351(9) Å, b = 26.824(5) Å, and c = 7.4641(15) Å. The gold and indium atoms define a complex three-dimensional [Au₃In₅] network with a broad range of Au−In (2.751(2) Å−3.0518(16) Å) and In−In (3.062(3) Å−3.3024(19) Å) distances. Magnetic susceptibility measurements of YbAu₂In₄ revealed a transition at 25 K. Below the transition, the susceptibility of YbAu₂In₄ follows Curie−Weiss behavior with an effective paramagnetic moment of 0.79 μ_B/Yb. Magnetic susceptibility measurements on Yb₂Au₃In₅ show a mixed valent ytterbium and the magnetic moment within the linear region (<100 K) of 1.95 μ_B/Yb. Heat capacity data for YbAu₂In₄ and Yb₂Au₃In₅ give Debye temperatures of 185 and 153 K, respectively.