Thermoelectric Properties of Sb₂Te₃-Based Nanocomposites with Graphite

Abstract

Antimony-telluride-based nanocomposite samples containing different weight fractions of graphite (Sb₂Te₃ + x% graphite, where x = 0.0, 0.5, 1.0, and 2.5%) are synthesized and studied. The samples are produced by a solid-state reaction with the use of a ball mill. X-ray diffraction measurements show that the Sb₂Te₃ phase is present in the nanocomposites. All of the diffraction peaks are identified as corresponding to the rhombohedral structure of symmetry $R\bar {3}m$. No additional peaks related to graphite are observed because of its low content. Moreover, the X-ray data show the insolubility of graphite in Sb₂Te₃: the peaks related to Sb₂Te₃ remain unchanged upon the addition of graphite. The thermal conductivity, thermoelectric power, and resistivity of the samples are studied in the temperature range 80 K ≤ T ≤ 320 K. The thermal conductivity k of the nanocomposite decreases several times compared to the thermal conductivity of single-crystal Sb₂Te₃ and reaches k ≈ 0.95 W m^–1 K^–1 at x = 0.5%. The parameter k unsteadily depends on the content of graphite. The thermoelectric power of the nanocomposites with graphite at x = 1.0% is higher compared to that of nanostructured Sb₂Te₃.