These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Structure and bonding in Yb4MgGe4: Yb2+/Yb3+ mixed-valency and charge separation.
    Author: Tobash PH, Bobev S.
    Journal: J Am Chem Soc; 2006 Mar 22; 128(11):3532-3. PubMed ID: 16536522.
    Abstract:
    Reported are the synthesis and the structural characterization of a new derivative of the RE5Tt4 family (RE = Rare-earth; Tt = Tetrel, = Si, Ge, i.e., group 14 element), Yb5-xMgxGe4 (x approximately 1). Crystal data for Yb4.04(1)Mg0.96(1)Ge4 at 23 degrees C: orthorhombic, space group Pnma (No. 62), Z = 4; a = 7.155(2) A, b = 14.769(5) A, c = 7.688(2) A; V = 812.5(4) A3. This phase is an example of a substitution of lanthanide metal (Yb) with a nonmagnetic element (Mg) within this structure type. Its structure can alternatively be described as an intergrowth of the hypothetical Yb2MgGe2, which features flat infinite [MgGe2]4- layers and the hypothetical YbGe with [Ge2]6- dimers. The flat [MgGe2]4- layers propagate in two dimensions (a and c), and they are offset by a distance of 1/4.a with respect to one another and are interspaced with layers of [Ge2]6- dimers and Yb cations filling the space between them. According to the structural and physical property data, Yb4MgGe4 is a heterogeneous mixed-valent compound, i.e. a system where one of the two symmetry-inequivalent Yb sites has atoms in closed-shell Yb2+ configuration, whereas the Yb3+ cations occupy a different crystallographic site.
    [Abstract] [Full Text] [Related] [New Search]