Synthesis and Characterization of Three New Lithium-Scandium Hexathiohypodiphosphates: Li4–3xScxP2S6 (x = 0.358), m-LiScP2S6, and t-LiScP2S6

Leslie Mareike Schoop, Roland Eger, Florian Pielnhofer, Christian Schneider, Jürgen Nuss, Bettina Valeska Lotsch

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Abstract

We report the first examples of lithium rare earth metal hexathiohypodiphosphates(IV). Three new lithium-scandium hexathiohypodiphosphates(IV) were synthesized and characterized. The compounds crystallize in three different structure types, featuring isolated ethane-like [P2S6]4– hexathiohypodiphosphate(IV) units. Li2.926Sc0.358P2S6 or Li4–3xScxP2S6 (x = 0.358) crystallizes in the space group P31m (no. 162) with a = b = 6.0966(5) Å, c = 6.5866(6) Å, V = 212.02(4) Å3, and Z = 1. The compound is isostructural to Li2FeP2S6 as well as the Li ion conductor Li4–2xMgxP2S6 (x = 1/3, 2/3). Monoclinic LiScP2S6 was found to be a layered compound with van der Waals gaps. The layers consist of edge sharing octahedra that are occupied by Li, Sc, and P2 in an alternating fashion. It is isostructural to LiAlP2S6 and crystallizes in the space group C2/c (no. 15) with a = 6.933(1) Å, b = 10.754(2) Å, c = 11.694(2) Å, β = 94.41(3)°, V = 869.3(3) Å3, and Z = 4. Trigonal LiScP2S6 crystallizes in the space group P31c (no. 163) with a = b = 6.363(1) Å, c = 12.386(3) Å, V = 434.3(2) Å3, and Z = 2, and is isostructural to AgInP2S6 and AgScP2S6. Its structure is closely related to the monoclinic version, except that trigonal LiScP2S6 features disordered [P2/2P6/6S6]4– units. The new phases were investigated by Raman spectroscopy, thermal analysis, and DFT calculations. We further demonstrate that Li4–3xScxP2S6 shows significantly enhanced Li ion conductivity compared to the parent compound Li4P2S6.

Original languageEnglish (US)
Pages (from-to)1854-1862
Number of pages9
JournalZeitschrift fur Anorganische und Allgemeine Chemie
Volume644
Issue number24
DOIs
StatePublished - Dec 31 2018

All Science Journal Classification (ASJC) codes

  • Inorganic Chemistry

Keywords

  • LiScPS
  • Lithium
  • Lithium ion conductivity
  • Lithium-scandium hexathiohypodiphosphate
  • Scandium

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