Morphology and the Thermoelectric Properties of γ-GdxDy1 – xS1.5 – y Solid Solution Ceramics

• Published in: Physics of the solid state 2020, Vol.62 (4), p.611-620
• Main Authors: Sotnikov, A. V., Bakovets, V. V., Ohta, Michihiro, Agazhanov, A. Sh, Stankus, S. V.
• Format: Article
• Language: English
• Subjects: Composition; Crystallites; Dysprosium; Electrical resistivity; Figure of merit; Gadolinium; Heat conductivity; Heat transfer; Morphology; Physics; Physics and Astronomy; Seebeck effect; Semiconductors; Solid solutions; Solid State Physics; Thermal conductivity; Thermoelectricity
• ISSN: 1063-7834; 1090-6460
• DOI: 10.1134/S1063783420040216

The temperature dependences of the Seebeck coefficient, the electrical conductivity ( T = 300–873 K) and also the heat conductivity coefficient, and the thermoelectric figure of merit ( T = 300–770 K) of polycrystalline samples of solid solutions based on gadolinium and dysprosium sulfides of compositions γ‑Gd x Dy 1 –   x S 1.49 ( x = 0.1, 0.2, 0.3, 0.4) have been studied. It is found that the morphological features of the samples, namely, specifically of the crystallite surface that causes a change in the number of the deformation centers, determines the thermal conductivity of γ-Gd x Dy 1 –   x S 1.49 solid solutions; the thermal conductivity of the composition with x = 0.2 is found to decrease anomalously. For this composition, the lowest values of the Seebeck coefficient –371 μV/K at 873 K, resistivity 880 μΩ m at 873 K, and the thermal conductivity coefficient 0.68 ± 0.03 W/m K at 770 K have been obtained; in this case, the thermoelectric figure of merit achieves the value ZT = 0.23.