title: A new look at bonding in trialuminides: reinvestigation of TaAl3.
abstract: Single crystals of TaAl3 were grown at high temperatures from an Al-rich, binary solution. TaAl3 adopts the D0(22) structure type, space group I4/mmm with a=3.8412(5) A, c=8.5402(17) A, and Z=2. The structure type, which is the preferred structure for all group 5 trialuminides and TiAl3 as well as the high-temperature form of HfAl3, is a binary coloring of the face-centered-cubic (fcc) arrangement. The distribution of Ta atoms creates a three-dimensional network of vertex and edge-sharing square pyramids of Al atoms. Temperature-dependent electrical resistivity and magnetic susceptibility measurements are consistent with TaAl3 being a metallic compound with a relatively low density of states at the Fermi surface. Furthermore, tight-binding electronic structure calculations are utilized to describe the bonding in these compounds and to compare their stability with respect to the alternative fcc-related, e.g., the D0(23) (ZrAl3-type) and the L1(2) (AuCu3-type), structures. A modified Wade's rule argument provides insights into the structural preferences.
authors.affiliation: Department of Chemistry, Iowa State University, Ames, Iowa 50011, USA.
authors.forename: Cathie L
authors.initials: CL
authors.lastname: Condron
authors.forename: Gordon J
authors.initials: GJ
authors.lastname: Miller
authors.forename: Joel D
authors.initials: JD
authors.lastname: Strand
authors.forename: Sergey L
authors.initials: SL
authors.lastname: Bud'ko
authors.forename: Paul C
authors.initials: PC
authors.lastname: Canfield