Synthesis and thermoelectric properties of Cu1.8 S

Abstract

The aim of this study was to determine the influence of synthesis method of Cu <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1.8</sub> S material for its thermoelectric properties. The material was synthesized by hydrothermal and high temperature method and then densified by Spark Plasma Sintering (SPS) technique. Structural, phase and chemical composition analyses were examined with X-ray diffraction (XRD) and scanning electron microscopy (SEM). The investigations of thermoelectric properties, i.e.: electrical conductivity, the Seebeck coefficient and the thermal conductivity, were carried out in the temperature range from RT to 910 K. On the basis of the experimental data, the temperature dependencies of the thermoelectric figure of merit ZT were calculated. Detailed analysis of all obtained results was performed withadditional insight into the role of the synthesis method on received thermoelectric properties. Superionic thermoelectric materials based on Cu <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> X (X = S, Se, Te) are intensively studied in recent years due to the very high values of their ZT parameter [1]. Unfortunately, their transport properties are unstable becouse of the high mobility of copper ions [2]. Cu <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1.8</sub> S is much more stable compared to Cu <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> S and used to be obtained mainly by the mechanical alloying method [3, 4]. In this work, the Cu <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1.8</sub> S material was received by hydrothermal synthesis and high-temperature synthesis, and then their transport properties were examined and compared.