Ames Laboratory; Chemistry
Chemistry, Ames Laboratory
Using density functional theory, the crystal structure variation of AAuAl (A = Ca, Sc, and Ti) from orthorhombic Co2Si-type to distorted hexagonal Fe2P-type and then Ni2In-type structures is shown to correlate with their electronic struc-tures and valence electron counts, sizes of the active metals A, and site preferences for Au and Al atoms, which are arranged to maximize Au−Al nearest neighbor contacts. An evaluation of chemical pressure imposed by the varying A metals using total energy vs. volume calculations indicates that larger unit cell volumes favor the orthorhombic structure whereas smaller vol-umes favor the hexagonal structures. The electronic origin of the Mg2Ga-type crystal structure of ScAuAl, refined as a distorted Fe2P-type supercell doubled along the c-axis, indicates a Peierls-type distortion mechanism of the Au-chains along the c-axis.
Department of Energy Subject Categories
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
Iowa State University Digital Repository, Ames IA (United States)