Monoclinic 122-Type BaIr(2)Ge(2) with a Channel Framework: A Structural Connection between Clathrate and Layered Compounds

A new 122-type phase, monoclinic BaIr(2)Ge(2) is successfully synthesized by arc melting; X-ray diffraction and scanning electron microscopy are used to purify the phase and determine its crystal structure. BaIr(2)Ge(2) adopts a clathrate-like channel framework structure of the monoclinic BaRh(2)Si(2)-type, with space group P2(1)/c. Structural comparisons of clathrate, ThCr(2)Si(2), CaBe(2)Ge(2), and BaRh(2)Si(2) structure types indicate that BaIr(2)Ge(2) can be considered as an intermediate between clathrate and layered compounds. Magnetic measurements show it to be diamagnetic and non-superconducting down to 1.8 K. Different from many layered or clathrate compounds, monoclinic BaIr(2)Ge(2) displays a metallic resistivity. Electronic structure calculations performed for BaIr(2)Ge(2) support its observed structural stability and physical properties.