Data di Pubblicazione:
2012
Citazione:
New Ternary Germanides La4Mg5Ge6and La4Mg7Ge6: Crystal Structure and Chemical Bonding / P. Solokha, S. De Negri, M. Skrobanska, A. Saccone, V. Pavlyuk, D.M. Proserpio. - In: INORGANIC CHEMISTRY. - ISSN 0020-1669. - 51:1(2012), pp. 207-214.
Abstract:
The synthesis, structural characterization, and chemical-bonding
peculiarities of the two new polar lanthanum−magnesium germanides
La4Mg5Ge6 and La4Mg7Ge6 are reported. The crystal structures of these
intermetallics were determined by single-crystal X-ray diffraction analysis.
The La4Mg5Ge6 phase crystallizes in the orthorhombic Gd4Zn5Ge6 structure
type [Cmc21, oS60, Z = 4, a = 4.5030(7) Å, b = 20.085(3) Å, c = 16.207(3) Å,
wR2 = 0.0451, 1470 F2 values, 93 variables]. The La4Mg7Ge6 phase represents
a new structure type with a monoclinic unit cell [C2/m, mS34, Z = 2, a =
16.878(3) Å, b = 4.4702(9) Å, c = 12.660(3) Å, β = 122.25(3)°, wR2 =
0.0375, 1466 F2 values, 54 variables]. Crystallographic analysis together
with linear muffin-tin orbital band structure calculations reveals the presence of strongly bonded 3D polyanionic [Mg−Ge]
networks balanced by positively charged La atoms in both stoichiometric compounds. The La4Mg5Ge6 compound is related to
Zintl phases, showing a prominent density of states pseudogap at the Fermi level. A distinctive feature of the La4Mg5Ge6 structure is
the presence of Ge−Ge covalent dumbbells; in La4Mg7Ge6, the higher Mg content generates a polyanionic network consisting
exclusively of Mg−Ge heterocontacts. Nevertheless, the frameworks of the two phases are structurally similar, as is highlighted in
this work.
Tipologia IRIS:
01 - Articolo su periodico
Elenco autori:
P. Solokha, S. De Negri, M. Skrobanska, A. Saccone, V. Pavlyuk, D.M. Proserpio
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