A New Look at Bonding in Trialuminides:  Reinvestigation of TaAl3

• Published in: Inorganic chemistry Vol. 42; no. 25; pp. 8371 - 8376
• Main Authors: Condron, Cathie L, Miller, Gordon J, Strand, Joel D, Bud'k, Sergey L, Canfield, Paul C
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 15-12-2003
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/ic034927m

Single crystals of TaAl3 were grown at high temperatures from an Al-rich, binary solution. TaAl3 adopts the D022 structure type, space group I4/mmm with a = 3.8412(5) Å, c = 8.5402(17) Å, 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 D023 (ZrAl3-type) and the L12 (AuCu3-type), structures. A modified Wade's rule argument provides insights into the structural preferences.