Yb_9+xCuMg_4–x (x = 0.034): A <i>κ</i>-Phase Formed by Lanthanoids

Autor(en)

Serena De Negri, Vitaliy Romaka, Paulo Solokha, Adriana Saccone, Gerald Giester, Herwig Michor, Peter F. Rogl

Abstrakt

Atom order in the crystal structures of Yb

₂Cu

_2-xMg (x = 0.17; Mo

₂FeB

₂-type; P4/mbm; a = 0.75592(2) nm; c = 0.40282(1) nm) and Yb

_9+xCuMg

_4-x (x = 0.034; Hf

₉Mo

₄B-type; P6

₃/mmc; a = 1.0169(5) nm; c = 1.0290(5) nm) was determined from powder and X-ray single-crystal counter data analyses supported by electron probe microanalyses. Among the group of the so-called κ-phases, Yb

_9+xCuMg

_4-x is the first representative formed by a lanthanoid element. The structure of this κ-phase can be viewed as a typical network of corner-connected empty Yb

₆-octahedra, which encompass Yb

₆Mg

₆-icosahedra (filled by a mix of Mg/Yb atoms) and Yb

₆-trigonal prisms centered by Cu atoms to complete the three-dimensional metal framework. From another point of view, the same structure is considered as built from infinite polyicosahedral columns of Yb

₉Mg

₄ composition with Cu atoms located in trigonal prismatic interstices, highlighting similarities with other Yb-rich Yb-Cu-Mg phases. Density functional theory (DFT) calculations classify Yb

₉CuMg

₄ as a polar intermetallic. Metallic-like behavior is inferred from the Sommerfeld constant, γ = 49.2 mJ/mol·K

², derived from the electronic density of states, calculated at the Fermi level. DFT integration of the f-density of states indicates almost completely filled f-states, revealing 13.6 and 13.7 electrons in the valence band for Yb1 and Yb2 atoms, respectively, close to the Yb

²⁺ ground state (

¹S

₀) for both Yb atoms. Magnetic susceptibility data recorded on the same compound are consistent with a nonmagnetic divalent Yb

²⁺ state. Temperature-dependent heat capacity data display a metallic behavior characterized by a small Sommerfeld constant γ = 64.8 mJ/mol·K

² and a rather low Debye temperature

_D = 140 K as typical for soft materials.

Organisation(en)

Institut für Mineralogie und Kristallographie, Institut für Materialchemie

Externe Organisation(en)

Università degli Studi di Genova, Lviv Polytechnic National University, Technische Universität Wien

Journal

Inorganic Chemistry

Band

55

Seiten

8174-8183

Anzahl der Seiten

10

ISSN

0020-1669

DOI

https://doi.org/10.1021/acs.inorgchem.6b01315

Publikationsdatum

07-2016

Peer-reviewed

Ja

ÖFOS 2012

104003 Anorganische Chemie, 104017 Physikalische Chemie, 104011 Materialchemie, 105113 Kristallographie

Schlagwörter

ASJC Scopus Sachgebiete

Inorganic Chemistry, Physical and Theoretical Chemistry

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/5f1c1ca0-3fe3-46b5-b828-8c544f44b71e