Ternary and Quaternary Rare-Earth Transition-Metal Germanides

• Author / Creator

  Zhang, Dong

• Ternary and quaternary germanides containing rare-earth and transition metals are of interest because of their structural diversity and the potential for interactions between f- and d-electrons. Within the Ce–Rh–Ge system, three new ternary phases Ce3Rh11Ge5, CeRh5Ge3, and CeRh3Ge2 were prepared and their structures were determined by powder and single-crystal X-ray diffraction. Their bonding was examined by calculating electron localization functions and performing a Bader charge analysis, which confirms the description of the structures as consisting of electropositive Ce atoms embedded within an anionic network of Rh and Ge atoms. Within the RE–M–X–Ge (RE = rare-earth metal; M = Mn–Ni; X = Ag, Cd) system, 73 quaternary germanides RE4M2XGe4 adopting the same monoclinic structure (Ho4Ni2InGe4-type) were prepared. A prominent feature in these germanides is the presence of deficient X sites coordinated weakly to Ge atoms in square planar geometry, which may have implications for the low thermal conductivity predicted in these compounds, as confirmed in Nd4Mn2AgGe4. Some representatives of these germanides exhibit additional disorder between the M and X atoms, as seen in Nd4(Mn0.78(1)Ag0.22(1))2Ag0.83(1)Ge4. Solid solutions of these germanides in combination with silicon was investigated in the series Nd4Mn2Cd(Ge1–ySiy)4, in which two intermediate members as well as the end members were characterized structurally.

• Subjects / Keywords

  • Intermetallic
  • Crystal structure
  • Germanides
  • Electronic structure
  • Thermal properties

• Graduation date

  Spring 2019

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/r3-8pqk-n069

• License

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