Temperature dependent local atomic displacements in NaSn2As2 system

G. M. Pugliese, F. Stramaglia, Y. Goto, K. Terashima, L. Simonelli, H. Fujiwara, A. Puri, C. Marini, M. Y. Hacisalihoglu, F. D'Acapito, T. Yokoya, T. Mizokawa, Y. Mizuguchi, N. L. Saini*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)


NaSn2As2 is mechanically exfoliable layered van der Waals (vdW) Zintl phase that is getting interesting due to its low thermal conductivity and recently observed superconductivity. Here, we have investigated the temperature dependent local structure of NaSn2As2 by a combined analysis of As K-edge and Sn K-edge extended x-ray absorption fine structure measurements. The system is intrinsically disordered with the interatomic distances largely consistent to those estimated by average structure measurements. The stretching force constants of different bond distances have been determined using temperature dependent mean square relative displacements. The Sn-As distance is the strongest bond in this system, having covalent nature, unlike the weaker interlayer distances which are characterized by vdW type bonding. Among them, As-Na distance is slightly weaker than Sn-Sn(i) below ∼200 K and tends to get stronger above this temperature. The anomalous behavior of As-Na bond suggests that the mechanical exfoliation in this system is likely to be temperature dependent. The anomaly in the interlayer atomic correlations may be due to a charge density wave-like instability around this temperature, indicated by earlier experiments. The local structure and disorder are discussed in relation to the physical properties of NaSn2As2

Original languageEnglish
Article number425402
JournalJournal of Physics Condensed Matter
Issue number42
Publication statusPublished - 2019 Jul 23

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics


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