Phase Composition and Thermoelectric Properties of Materials Based on Cu2 –xSe (0.03 ≤ x ≤ 0.23)

• Published in: Nanobiotechnology Reports (Online) 2021, Vol.16 (3), p.351-356
• Main Authors: Ivanov, A. A., Akchrin, R. Kh, Bogomolov, D. I., Bublik, V. T., Voronov, M. V., Lavrentev, M. G., Panchenko, V. P., Parkhomenko, Y. N., Tabachkova, N. Y.
• Format: Article
• Language: English
• Subjects: Chemical composition; Chemistry and Materials Science; Composition effects; Copper selenides; Current carriers; Deviation; Figure of merit; Functional and Construction Nanomaterials; Industrial and Production Engineering; Machines; Manufacturing; Material properties; Materials Science; Nanotechnology; Phase composition; Plasma sintering; Processes; Room temperature; Spark plasma sintering; Thermal conductivity; Thermoelectric materials; Two phase materials
• ISSN: 2635-1676; 1995-0780; 2635-1684; 1995-0799
• DOI: 10.1134/S2635167621030083

The phase composition and thermoelectric properties of Cu 2 – x Se samples with different deviations from the stoichiometric composition ( x = 0.03, 0.08, 0.13, 0.18, and 0.23) are studied. Bulk thermoelectric materials based on Cu 2 – x Se are synthesized by spark plasma sintering. The phase composition is studied using the X-ray diffraction method. Depending on the chemical composition, the materials based on Cu 2 – x Se at room temperature can be either a single-phase material containing only the cubic β-Cu 2 Se phase or a two-phase material containing a mixture of monoclinic α-Cu 2 Se and cubic β-Cu 2 Se phases. It is shown that the deviation of the stoichiometric composition has a substantial effect on the electrophysical characteristics of the material. With an increase in the deviation of the stoichiometric composition, the concentration of the main charge carriers in Cu 2 – x Se increases because of the formation of copper vacancies. The change in the thermal conductivity substantially contributes to the thermoelectric figure of merit of Cu 2 – x Se compounds. In the investigated range of chemical compositions, the maximum values of thermoelectric figure of merit around ZT ~ 1.3 at 600°C are observed in samples with the Cu 1.97 Se composition.