4 years ago

The Influence of the Valence Electron Concentration on the Structural Variation of the Laves Phases MgNi2–xGex

The Influence of the Valence Electron Concentration on the Structural Variation of the Laves Phases MgNi2–xGex
Lisa Siggelkow, Thomas F. Fässler, Viktor Hlukhyy
The influence of the partial substitution of Ni atoms by the similarly sized but electron-richer Ge atoms with a similar electronegativity in the binary Laves phase MgNi2 is investigated. A small degree of substitution in MgNi2–xGex (x = 0.1) leads to the change of the hexagonal MgNi2-type structure (C36) to the cubic C15 type, whereas higher amounts of Ge lead to the formation of the two new Laves phases Mg2Ni3Ge and MgNi1.30(5)Ge0.70, which were synthesized by the direct reaction of the elements in alumina and niobium crucibles using an induction furnace. The crystal structures of the two phases were determined by single-crystal X-ray diffraction. Mg2Ni3Ge (hR18-MgNi2–xGex, x = 0.5) crystallizes in the Y2Rh3Ge-type structure, which is an ordered variant of the cubic Laves phase MgCu2: space group R3m, a = 5.0300(7), c = 11.330(2) Å. hP36-MgNi2–xGex with x = 0.70(6) crystallizes as a superstructure of the hexagonal Laves phase MgZn2: space group P63/mcm, a = 8.6946(2), c = 7.8127(3) Å. MgNi1.3Ge0.7 represents a new structure type. Gradual substitution of Ni by Ge in the Laves phase MgNi2 corresponds to an increase in the valence electron concentration (VEC) in the ternary phase system and leads to the series MgCu2 (C15 type), hR18-Mg2Ni3Ge (superstructure of MgCu2 type), and hP36-MgNi1.3Ge0.7 (superstructure of MgZn2 type). The electronic structures are discussed based on band structure calculations, and the results are compared to the pristine Laves phase MgNi2, MgCu2, and MgZn2 with VEC = 2/3, 4/3 and 2, respectively.

Publisher URL: http://onlinelibrary.wiley.com/resolve/doi

DOI: 10.1002/zaac.201700180

You might also like
Discover & Discuss Important Research

Keeping up-to-date with research can feel impossible, with papers being published faster than you'll ever be able to read them. That's where Researcher comes in: we're simplifying discovery and making important discussions happen. With over 19,000 sources, including peer-reviewed journals, preprints, blogs, universities, podcasts and Live events across 10 research areas, you'll never miss what's important to you. It's like social media, but better. Oh, and we should mention - it's free.

  • Download from Google Play
  • Download from App Store
  • Download from AppInChina

Researcher displays publicly available abstracts and doesn’t host any full article content. If the content is open access, we will direct clicks from the abstracts to the publisher website and display the PDF copy on our platform. Clicks to view the full text will be directed to the publisher website, where only users with subscriptions or access through their institution are able to view the full article.