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

Autor: 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.
Zdroj: Nanobiotechnology Reports; May 2021, Vol. 16 Issue: 3 p351-356, 6p
Abstrakt: Abstract: The phase composition and thermoelectric properties of Cu2 –xSe 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 Cu2 –xSe 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 Cu2 –xSe at room temperature can be either a single-phase material containing only the cubic β-Cu2Se phase or a two-phase material containing a mixture of monoclinic α-Cu2Se and cubic β-Cu2Se 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 Cu2 –xSe increases because of the formation of copper vacancies. The change in the thermal conductivity substantially contributes to the thermoelectric figure of merit of Cu2 –xSe 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 Cu1.97Se composition.
Databáze: Supplemental Index