Structural, optical and transport properties of layered europium disulfide synthesized under high pressure

Materials readily forming stacks down to monolayer thickness and simultaneously possessing a finite bandgap are highly attractive from both fundamental and applied points of view. In this work, high-quality single-crystal samples of a novel layered compound, europium disulfide (EuS 2 ), were synthes...

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Bibliographic Details
Published in:CrystEngComm 2023-05, Vol.25 (19), p.2966-2978
Main Authors: Ekimov, E. A, Nikolaev, S. N, Ivanova, A. G, Sidorov, V. A, Shiryaev, A. A, Usmanov, I. I, Vasiliev, A. L, Artemov, V. V, Kondrin, M. V, Chernopitsskiy, M. A, Krivobok, V. S
Format: Article
Language:English
Subjects:
Crystal defects
Electrical resistivity
Energy gap
Europium
Europium compounds
Flakes (defects)
High pressure
High temperature
Infrared spectra
Low temperature
Optical properties
P-type semiconductors
Seebeck effect
Single crystals
Synthesis
Transport properties
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Summary:Materials readily forming stacks down to monolayer thickness and simultaneously possessing a finite bandgap are highly attractive from both fundamental and applied points of view. In this work, high-quality single-crystal samples of a novel layered compound, europium disulfide (EuS 2 ), were synthesized under high-temperature-high-pressure conditions and characterized by complementary methods. According to single-crystal X-ray diffraction, the compound crystallizes in a monoclinic structure (space group P 2 1 / a ). Flakes down to 1-2 nm thick can be obtained by mechanical exfoliation; the angular dependence of the polarized Raman intensity allows determination of the flakes' orientation. Infrared spectra demonstrate a rich structure in a broad energy range, possibly arising from excitonic effects and interatomic transitions in Eu ions. Measurements of the Seebeck coefficient and ab initio modeling show that the material is a p-type semiconductor with a 0.9 eV indirect bandgap. At low temperatures, electrical conductivity follows Mott's law, implying the presence of defects, possibly related to the disordering of covalent S-S bonds. A novel layered compound - europium disulfide - was synthesized under high-temperature-high-pressure conditions and characterized by complementary methods.
ISSN:1466-8033
1466-8033
DOI:10.1039/d2ce01647h