Phase Transformation Driven by Valence Electron Concentration: Tuning Interslab Bond Distances in Gd5GaxGe4-xJournal of the American Chemical Society
Publication VersionPublished Version
AbstractX-ray single crystal and powder diffraction studies on the Gd5GaxGe4-x system with 0 ≤ x ≤ 2.2 reveal dependence of interslab T−T dimer distances and crystal structures themselves on valence electron concentration (T is a mixture of Ga and Ge atoms). While the Gd5GaxGe4-x phases with 0 ≤ x ≤ 0.6 and valence electron concentration of 30.4−31 e-/formula crystallize with the Sm5Ge4-type structure, in which all interslab T−T dimers are broken (distances exceeding 3.4 Å), the phases with 1 ≤ x ≤ 2.2 and valence electron concentration of 28.8−30 e-/formula adopt the Pu5Rh4- or Gd5Si4-type structures with T−T dimers between the slabs. An orthorhombic Pu5Rh4-type structure, which is intermediate between the Gd5Si4- and Sm5Ge4-type structures, has been identified for the Gd5GaGe3 composition. Tight-binding linear-muffin-tin-orbital calculations show that substitution of three-valent Ga by four-valent Ge leads to larger population of the antibonding states within the dimers and, thus, to dimer stretching and eventually to dimer cleavage.
Copyright OwnerAmerican Chemical Society
Citation InformationYurij Mozharivskyj, Wonyoung Choe, Alexandra O. Pecharsky and Gordon J. Miller. "Phase Transformation Driven by Valence Electron Concentration: Tuning Interslab Bond Distances in Gd5GaxGe4-x" Journal of the American Chemical Society Vol. 125 Iss. 49 (2003) p. 15183 - 15190
Available at: http://works.bepress.com/gordon-miller/75/