Phase characterization, thermal stability, high-temperature transport properties, and electronic structure of rare-earth zintl phosphides Eu 3M2P4 (M = Ga, In)

Tanghong Yi, Gaigong Zhang, Naohito Tsujii, Jean Pierre Fleurial, Alex Zevalkink, G. Jeffrey Snyder, Niels Grønbech-Jensen, Susan M. Kauzlarich

Research output: Contribution to journalArticlepeer-review

7 Scopus citations

Abstract

Two rare-earth-containing ternary phosphides, Eu3Ga 2P4 and Eu3In2P4, were synthesized by a two-step solid-state method with stoichiometric amounts of the constitutional elements. Refinements of the powder X-ray diffraction are consistent with the reported single-crystal structure with space group C2/c for Eu3Ga2P4 and Pnnm for Eu3In 2P4. Thermal gravimetry and differential scanning calorimetry (TG-DSC) measurements reveal high thermal stability up to 1273 K. Thermal diffusivity measurements from room temperature to 800 K demonstrate thermal conductivity as low as 0.6 W/m·K for both compounds. Seebeck coefficient measurements from room temperature to 800 K indicate that both compounds are small band gap semiconductors. Eu3Ga2P 4 shows p-type conductivity and Eu3In2P 4 p-type conductivity in the temperature range 300-700 K and n-type conductivity above 700 K. Electronic structure calculations result in band gaps of 0.60 and 0.29 eV for Eu3Ga2P4 and Eu 3In2P4, respectively. As expected for a valence precise Zintl phase, electrical resistivity is large, approximately 2600 and 560 mΩ·cm for Eu3Ga2P4 and Eu 3In2P4 at room temperature, respectively. Measurements of transport properties suggest that these Zintl phosphides have potential for being good high-temperature thermoelectric materials with optimization of the charge carrier concentration by appropriate extrinsic dopants.

Original languageEnglish (US)
Pages (from-to)3787-3794
Number of pages8
JournalInorganic Chemistry
Volume52
Issue number7
DOIs
StatePublished - Apr 1 2013

ASJC Scopus subject areas

  • Inorganic Chemistry
  • Physical and Theoretical Chemistry

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