Temperature-dependent crystallographic studies and electronic structure of Ba2Cd3Bi4

The ternary compound Ba2Cd3Bi4 crystallizes in the C-centered orthorhombic space group Cmce (No. 64) with its own type (Pearson's symbol oC36; a=7.019(3) Å, b=17.389(7) Å and c=9.246(3) Å determined at –23 °C). Although the structure of this intermetallic compound with transition metal in d10 configuration has already been established, details such as the rather unusual coordination of the Cd-atoms and the elongation in specific direction of their anisotropic displacement parameters had not been explained. These facts, along with the higher than 12% R-values from the original structure determination prompted the systematic structural studies by single-crystal X-ray diffraction at several different temperatures. The results from these studies confirm strong temperature dependence of the cadmiums’ anisotropic displacement parameters, concomitant rather large thermal expansion along the crystallographic b-axis. Electronic band structure calculations performed by the TB-LMTO-ASA method are also reported.

Ba2Cd3Bi4, a long-known ternary intermetallic phase whose structure had not been well characterized, was reexamined and the structure refined at four different temperatures. The study proved the existence of a small position disorder, associated with the weakly bound Cd atoms.Figure optionsDownload as PowerPoint slide