Zintl Phases K<inf>4–x</inf>Na<inf>x</inf>Si<inf>4</inf> (1 ≤ x ≤ 2.2) and K<inf>7</inf>NaSi<inf>8</inf>: Synthesis, Crystal Structures, and Solid-State NMR Spectroscopic Investigations
European Journal of Inorganic Chemistry
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Scherf, L., Pecher, O., Griffith, K., Haarmann, F., Grey, C., & Fässler, T. (2016). Zintl Phases K<inf>4–x</inf>Na<inf>x</inf>Si<inf>4</inf> (1 ≤ x ≤ 2.2) and K<inf>7</inf>NaSi<inf>8</inf>: Synthesis, Crystal Structures, and Solid-State NMR Spectroscopic Investigations. European Journal of Inorganic Chemistry, 2016 4674-4682. https://doi.org/10.1002/ejic.201600735
The Zintl phases K₄₋ₓNaₓSi₄ (1 ≤ x ≤ 2.2) and K₇NaSi₈ are the first representatives of the K–Na–Si system, and both contain tetrahedral [Si₄]⁴⁻ clusters and a charge-balancing number of K⁺ and Na⁺ cations. All phases of K₄₋ₓNaₓSi₄ (1 ≤ x ≤ 2.2) crystallize in a new structure type with space group P2₁/n, as determined by single-crystal X-ray diffraction analysis of the parent phase K₃NaSi₄. Rietveld refinement of the X-ray diffraction data showed that the solid solutions follow Vegard's rule. K₇NaSi₈ can only be synthesized by diffusion-controlled reaction of binary precursors and is isostructural with known A₇A′T₈ (A = Na–Cs; A′ = Li, Na; T = Si, Ge) phases. A combination of solid-state NMR investigations and quantum mechanical calculations served to show the anisotropic chemical bonding behavior of all the atoms in K₇NaSi₈, which is additionally compared with the related phases A₇NaSi₈ (A = Rb, Cs).
We gratefully acknowledge fruitful discussions with Dr. Rachel N. Kerber (Cambridge). L. M. S. is grateful for financial support by the Fonds der Chemischen Industrie and a fellowship from the Studienstiftung des deutschen Volkes. This work was performed using the Darwin Supercomputer of the University of Cambridge High Performance Computing Service (http://www.hpc.cam.ac.uk/), provided by Dell Inc. using Strategic Research Infrastructure Funding from the Higher Education Funding Council for England and funding from the Science and Technology Facilities Council. K. J. G. thanks the Winston Churchill Foundation of the United States and the Herchel Smith Scholarship for financial support.
European Commission (655444)
External DOI: https://doi.org/10.1002/ejic.201600735
This record's URL: https://www.repository.cam.ac.uk/handle/1810/257438