Low-temperature structure and lattice dynamics of the thermoelectric clathrate Sn 24P 19.3I 8

Vladimir V. Novikov, Alexander V. Matovnikov, Dmitrii V. Avdashchenko, Nikolai V. Mitroshenkov, Evgeny Dikarev, Satoshi Takamizawa, Maria A. Kirsanova, Andrei V. Shevelkov

Research output: Contribution to journalArticlepeer-review

18 Citations (Scopus)

Abstract

The crystal structure of the thermoelectric clathrate Sn 24P 19.3I 8 was determined down to 10 K showing no variations with the temperature. Even at 10 K Sn 24P 19.3I 8 crystallizes in the type-I clathrate structure, space group Pm3-n, with the cubic unit cell parameter ranging from 10.9173 at 10 K to 10.9554 at room temperature. In its crystal structure, tin and phosphorus atoms form the framework that traps the guest iodine atoms in the polyhedral cavities of two different shapes. The temperature-dependent crystal structure data and the results of the heat capacity measurements revealed the localized vibrations of the guest atoms inside the oversized cavities with the characteristic Einstein temperatures of θ E1 = 60 K and θ E2 = 78 K, whereas the characteristic Debye temperature for Sn 24P 19.3I 8 is 265 K. The room temperature lattice thermal conductivity was calculated using the Debye model to be κ L = 0.85 W m -1 K -1, which is in excellent agreement with the experimentally measured data and demonstrates that the thermal conductivity is almost entirely phononic.

Original languageEnglish
Pages (from-to)174-179
Number of pages6
JournalJournal of Alloys and Compounds
Volume520
DOIs
Publication statusPublished - 15 Apr 2012

Keywords

  • Clathrates
  • Crystal structure
  • Heat capacity
  • Lattice dynamics
  • Thermoelectric materials

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