Issue 5, 2020

Measured and simulated thermoelectric properties of FeAs2−xSex (x = 0.30–1.0): from marcasite to arsenopyrite structure

Abstract

FeAs2−xSex (x = 0.30–1.0) samples were synthesized as phase pure powders by conventional solid-state techniques and as single crystals (x = 0.50) from chemical vapor transport. The composition of the crystals was determined to be Fe1.025(3)As1.55(3)Se0.42(3), crystallizing in the marcasite structure type, Pnnm space group. FeAs2−xSex (0 < x < 1) was found to undergo a marcasite-to-arsenopyrite (P21/c space group) structural phase transition at x ∼ 0.65. The structures are similar, with the marcasite structure best described as a solid solution of As/Se, whereas the arsenopyrite has ordered anion sites. Magnetic susceptibility and thermoelectric property measurements from 300–2 K were performed on single crystals, FeAs1.50Se0.50. Paramagnetic behavior is observed from 300 to 17 K and a Seebeck coefficient of −33 μV K−1, an electrical resistivity of 4.07 mΩ cm, and a very low κl of 0.22 W m−1 K−1 at 300 K are observed. In order to determine the impact of the structural transition on the high-temperature thermoelectric properties, polycrystalline FeAs2−xSex (x = 0.30, 0.75, 0.85, 1.0) samples were consolidated into dense pellets for measurements of thermoelectric properties. The x = 0.85 sample shows the best thermoelectric performance. The electronic structure of FeAsSe was calculated with DFT and transport properties were approximately modeled above 500 K.

Graphical abstract: Measured and simulated thermoelectric properties of FeAs2−xSex (x = 0.30–1.0): from marcasite to arsenopyrite structure

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Article information

Article type
Paper
Submitted
02 Jūn. 2020
Accepted
24 Jūl. 2020
First published
27 Jūl. 2020
This article is Open Access
Creative Commons BY-NC license

Mater. Adv., 2020,1, 1390-1398

Measured and simulated thermoelectric properties of FeAs2−xSex (x = 0.30–1.0): from marcasite to arsenopyrite structure

C. J. Perez, K. P. Devlin, C. M. Skaggs, X. Tan, C. E. Frank, J. R. Badger, C. Kang, T. J. Emge, S. M. Kauzlarich, V. Taufour, G. Kotliar, S. H. Lapidus and M. Greenblatt, Mater. Adv., 2020, 1, 1390 DOI: 10.1039/D0MA00371A

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