Investigation in the binary system Yb-Ga: crystal structure of the Ga-rich compound YbGa3.34.
Compounds within the Yb-Ga binary system were prepared by direct melting of the elements, and their crystal structure was solved from single crystal X-ray diffraction. YbGa(2) crystallizes in the hexagonal system, P6(3)/mmc, a = 4.4527(2), c = 7.1969(3) A, and YbGa(4) is monoclinic, C2/m, a = 6.129(2), b = 6.1096(14), c = 6.097(2) A, beta = 119.05(5) degrees . A new compound of formula YbGa(3.34) was identified in this system, and its crystal structure determined in the orthorhombic Immm space group, a = 4.2049(4), b = 4.3320(5), c = 25.691(3) A. While atoms are fully ordered in YbGa(2) and YbGa(4), partial atomic disorder occurs in YbGa(3.34) where gallium triangular units are found to substitute for some Yb atoms. The electronic structures have been calculated by first principles density functional theory methods using ordered models in supercells. Crystal structures and bonding therein are analyzed on the basis of gallium three-dimensional (3D) anionic networks and are compared with similar compounds. YbGa(3.34) marks the boundary between layered and 3D intergrown gallium frameworks.
Agrégats, Interfaces, Materiaux pour l'Energie Institut Charles Gerhardt, UMR 5253 CNRS UM2, CC015, Université de Montpellier 2, Sciences et Techniques du Languedoc, 34095 Montpellier Cedex 5, France. mtillard@univ-montp2.fr
Monique
M
Tillard
Claude
C
Belin