Decomposition behavior and thermoelectric properties of copper selenide—graphite composites

Cu2Se is a high ZT material consisting of cheap and earth abundant elements. Its thermoelectric performance mainly based on very low thermal conductivity associated with mobile atoms. This comes the drawback critical voltage, over which decomposes to elemental copper copper-deficient Cu2−xSe phase. Composites selenide graphite do not enhance voltage significantly as completely encapsulated by graphite. Thermoelectric properties pellets such composites obtained mixing pressing powder flakes are comparable pristine Cu2Se, but stability increases remarkably. Samples different grain sizes show that reproducibility measurements worse for larger grains, in addition lead inferior performance. Higher contents increase both electrical conductivity, an optimum figure merit observed fine-grained samples 4 wt. %