Реферат: Thermoelectric materials have attracted considerable attention due to their possibility for the direct conversion of waste heat into electrical energy. The thermoelectric generators (TEGs) based on the high-efficient thermoelectric materials could provide an alternative for traditional power generation sources. In recent years, material science is focused on the optimization of existing and development of new high-performance thermoelectric materials based on lanthanide and transition metal chalcogenides. The electrophysical properties of the thermoelectric materials are significantly affected by the electronic structure features. For instance, Seebeck coefficient (S) is one of the main characteristics of the thermoelectric materials and can be represented as follows: , (1) where k is the Boltzmann constant, e – the electron charge, Nc and Nv – the effective densities of states (DOS) in the conduction and the valence band, n, p, μn and μp – the concentration and mobility of electrons (n) and holes (p), respectively. As it can be seen from the equation (1), the Seebeck coefficient value is determined by the DOS distribution in the conduction and the valence band. Thus, the electronic structure study is one of the key aspects in the prediction and optimization of the thermoelectric properties of the functional materials. For p-type semiconductors, the thermoelectric properties are determined by the DOS distribution in the valence band, for n-type semiconductors – the distribution in the conduction band. The cation-substituted solid solutions MxMn1-xS (M – transition metal or lanthanide) based on MnS-matrix are promising functional materials with magnetic and thermoelectric properties. The functional properties of MxMn1-xS could be modified by the type and concentration of the doping atoms (M). The cation-substituted solid solutions LnxMn1-xS with lanthanides have demonstrated the most promising values of Seebeck coefficient (up to 18000 μV/K for Gd0.01Mn0.05S at 900K /1/ ). This fact allows one to consider the lanthanide-dopes solid solutions as promising functional materials. Here we report a study of the electronic structure features of the lanthanide-doped solid solutions LnxMn1-xS (Ln = Dy, Tm, Yb; x = 0.01; 0.05). The data on the conduction band structure could be obtained by the X-ray absorption edges near edge structure (XANES) spectroscopy. The local environment and oxidation state of sulfur atoms in LnxMn1-xS was unaffected by cationic substitution. The combination of the experimental data with results of quantum-chemical calculations allowed one to determine the partial contributions of DOS in the absorption edge structure, thereby, to study the features of the conduction band electronic structure formation of LnxMn1-xS. The authors are grateful for support to the Ministry of Science and Higher Education of the Russian Federation (project No. 121031700313-8).

Библиографическая ссылка: Syrokvashin M. , Korotaev E. , Nikolenko A.
Conduction Band Electronic Structure Features of Manganese Sulfide Solid Solutions Doped with Lanthanides
International Conference "Synchrotron and Free electron laser Radiation: generation and application" 27-30 Jun 2022