Electron-Precise Semiconducting ReGa2Ge: Extending the IrIn3 Structure Type to Group 7 of the Periodic Table

Maxim S Likhanov; Valeriy Yu Verchenko; Andrei A Gippius; Sergei V Zhurenko; Alexey V Tkachev; Zheng Wei; Evgeny V Dikarev; Alexey N Kuznetsov; Andrei V Shevelkov

doi:10.1021/acs.inorgchem.0c01805

Electron-Precise Semiconducting ReGa₂Ge: Extending the IrIn₃ Structure Type to Group 7 of the Periodic Table

Inorg Chem. 2020 Sep 8;59(17):12748-12757. doi: 10.1021/acs.inorgchem.0c01805. Epub 2020 Aug 26.

Authors

Maxim S Likhanov¹, Valeriy Yu Verchenko^{1

2}, Andrei A Gippius^{3

4}, Sergei V Zhurenko^{3

4}, Alexey V Tkachev⁴, Zheng Wei⁵, Evgeny V Dikarev⁵, Alexey N Kuznetsov^{1

6}, Andrei V Shevelkov¹

Affiliations

¹ Department of Chemistry, Lomonosov Moscow State University, Moscow, 119991, Russia.
² National Institute of Chemical Physics and Biophysics, Tallinn, 12618, Estonia.
³ Department of Physics, Lomonosov Moscow State University, Moscow 119991, Russia.
⁴ P.N. Lebedev Physics Institute RAS, Moscow 119991, Russia.
⁵ Department of Chemistry, University at Albany, SUNY, Albany, New York 12222, United States.
⁶ N. S. Kurnakov Institute of General and Inorganic Chemistry RAS, Moscow, 119991, Russia.

PMID: 32845622
DOI: 10.1021/acs.inorgchem.0c01805

Abstract

Intermetallic compounds with semiconducting properties are rare, but they give rise to advanced materials for energy conversion and saving applications. Here, we present ReGa₂Ge, a new electron-precise narrow-gap intermetallic semiconductor. The compound crystallizes in the IrIn₃ structure type (space group P4₂/mnm, a = 6.5734(3) Å, c = 6.7450(8) Å, and Z = 4), where Re atoms occupy the Ir site, while Ga and Ge jointly populate the In sites. ^69,71Ga nuclear quadrupole resonance spectroscopy indicates nonstatistical partially ordered distribution of Ga and Ge over two available crystallographic sites; however, the Ga:Ge ratio is exactly 2:1 without noticeable homogeneity range. The stoichiometry of ReGa₂Ge ensures its precise valence electron count, which is 17 e^- per formula unit. Accordingly, a narrow energy gap opens up at the Fermi energy in the electronic structure. Electrical resistivity, Seebeck coefficient, and thermal conductivity are in agreement with the semiconducting behavior deduced from the electronic structure calculations and point to prospective thermoelectric properties at high temperatures. Bonding analysis reveals dominant covalency in Re-E (E = Ga, Ge) and Re-Re interactions.