ELECTRONIC AND OPTICAL PROPERTIES OF QUATERNARY SULFIDE Tl2HgSnS4
DOI:
https://doi.org/10.32782/pet-2024-2-4Keywords:
electronic and optical properties, electronic structure, atomic coordinates, absorption edgeAbstract
Among the sequaternary chalcogenides, thallium, mercury, tinsulfide Tl2HgSnS4 is of particular interest. This sulfide is a unique quaternary compound that exists in the quasi-ternary system Tl2S-HgS-SnS2. Its non-centrosymmetric tetragonal structure (I4-2m) suggests some promising use of Tl2HgSnS4 in nonlinear optics. Mercury and tin atoms have four sulfur atoms in their immediate surroundings. In the Tl2HgSnS4 structure, thallium atoms occupy 4c Wyckoff positions, mercury atoms occupy 2b, tin atoms fill 2a, and sulfur atoms occupy 8i positions. In the Tl2HgSnS4 structure, Tl atoms are characterized by a tetragonal-antiprismatic surrounding by S atoms. In addition, thallium, mercury, and tin atoms form trigonal prisms in the immediate surroundings of sulfur atoms in the Tl2HgSnS4structure. It is known that knowledge of electronic and optical properties, as well as the features of the nature of chemical bonding in solids are of great importance, since it allows to understand and predict the physicochemical properties of the compounds. In this work, we have conducted a combined theoretical and experimental study of the electronic structure and optical properties of the Tl2HgSnS4 crystal. In particular, we have investigated the X-ray photoelectron (XP) spectra of core level and valence electrons (VB), as well as the X-ray emission (XE) S Kβ1,3 band (valence S p states) for the Tl2HgSnS4 crystal grown by the Bridgman-Stockbarger method. Particularly, in this study, we have developed an effective method for experimental studying the electronic structure of crystals by X-ray photoelectron spectroscopy (XPS), which allows eliminating the presence of hydrocarbon impurities adsorbed on the crystal surface. To estimate the band gap energy of the Tl2HgSnS4 crystal, the optical absorption edge at room temperature was investigated. To verify the experimental results, ab initio calculations of the optical absorption edge of the Tl2HgSnS4 compound were performed.
References
Piskach L. V., Mozolyuk M. Yu, Fedorchuk A.O., et al. Phase equilibria in the Tl2S–HgS–SnS2system at 520 K and crystal structure of Tl2HgSnS4. Chem. Met. Alloys, 2017. P. 136–141.
Atuchin V. V., Galashov E. N., Khyzhun O. Y., Bekenev V. L., Pokrovsky L. D., Borovlev Y. A., Zhdankov V. N. Low Thermal Gradient Czochralski growth of large CdWO4 crystals and electronic properties of (010) cleaved surface. J. Solid State Chem, 2016. V. 236. P. 24–31.
Lavrentyev A. A., Gabrelian B. V., Vu V. T., Shkumat P. N., Ocheretova V. A., Parasyuk O. V., O. Y. Khyzhun. Electronic structure and optical properties of Cu2CdGeS4: DFT calculations and X-ray spectroscopy measurements. Opt. Mater., 2015. V. 47. P. 435–444
Ocheretova V. A., Parasyuk O. V., Fedorchuk A. O., Khyzhun O. Y. Electronic structure of Cu2CdGeSe4 single crystalas determined from X-ray spectroscopy data. Mater. Chem. Phys., 2015. V. 160. P. 345–351.
Tarasova A. Y., Isaenko L. I., Kesler V. G., Pashkov V. M., Yelisseyev A. P., Denysyuk N. M., Khyzhun O. Y. Electronic structure and fundamental absorption edges of KPb2Br5, K0.5Rb0.5Pb2Br5 and RbPb2Br5 single crystals. J. Phys. Chem. Solids, 2012. V. 73. P. 674–682.
Vu T. V., Lavrentyev A. A., Gabrelian B. V., Ocheretova V. A., Parasyuk O. V., Khyzhun O. Y. Electronic bandstructure and optical constants of Pb2GeS4: Abinitiocalculationsand X-rayspectroscopyexperiments. J. Mater. Sci.: Mater. Electron., 2018. V. 29, P. 16088-16100.
Briggs, D. Seach P.M. Practical Surface Analysis (2nd Ed.): Vol. 1: Auger and X-Ray Photoelectron Spectroscopy, John Willey & Sons Ltd., Chichester, 1990.
Perdew J. P., Burke S., Ernzerhof M. Generalized Gradient Approximation Made Simple. Phys. Rev. Lett. 1996. V. 77, P. 3865–3868.
