Intricate Short-Range Ordering and Strongly Anisotropic Transport Properties of Li1-xSn2+xAs2

Kathleen Lee, Derrick Kaseman, Sabyasachi Sen, Ivan Hung, Zhehong Gan, Birgit Gerke, Rainer Pöttgen, Mikhail Feygenson, Jörg Neuefeind, Oleg I. Lebedev, Kirill Kovnir

Research output: Contribution to journalArticlepeer-review

34 Scopus citations

Abstract

A new ternary compound, Li1-xSn2+xAs2, 0.2 < x < 0.4, was synthesized via solid-state reaction of elements. The compound crystallizes in a layered structure in the R3¯m space group (No. 166) with Sn-As layers separated by layers of jointly occupied Li/Sn atoms. The Sn-As layers are comprised of Sn3As3 puckered hexagons in a chair conformation that share all edges. Li/Sn atoms in the interlayer space are surrounded by a regular As6 octahedron. Thorough investigation by synchrotron X-ray and neutron powder diffraction indicate no long-range Li/Sn ordering. In contrast, the local Li/Sn ordering was revealed by synergistic investigations via solid-state 6,7Li NMR spectroscopy, HRTEM, STEM, and neutron and X-ray pair distribution function analyses. Due to their different chemical natures, Li and Sn atoms tend to segregate into Li-rich and Sn-rich regions, creating substantial inhomogeneity on the nanoscale. The inhomogeneous local structure has a high impact on the physical properties of the synthesized compounds: the local Li/Sn ordering and multiple nanoscale interfaces result in unexpectedly low thermal conductivity and highly anisotropic resistivity in Li1-xSn2+xAs2. (Graph Presented).

Original languageEnglish
Pages (from-to)3622-3630
Number of pages9
JournalJournal of the American Chemical Society
Volume137
Issue number10
DOIs
StatePublished - Mar 18 2015

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