High thermoelectric performance of Cu2Te1 − x Sex alloys synthesized by mechanical alloying and hydrogen decrepitation method

Cu₂Te_1 − xSe_x alloys (x = 0, 0.05, 0.1, 0.15 and 0.2) were prepared by ball milling followed by hydrogen decrepitation method. The structural, chemical state and morphology of the prepared samples were analysed using XRD, XPS and FESEM analysis. From the XRD analysis, it is confirmed that pure phase of Cu₂Te is formed in pristine and additional structural formation was present in substituted samples. The electrical resistivity (ρ) and Seebeck coefficient (S) of Cu₂Te_1 − xSe_x alloys (x = 0,0.05,0.1,0.15 and 0.2) were measured as a function of temperature range between 303 and 673 K. The ρ of Cu₂Te at 673 K is 3.88 × 10^–4 Ωm and drastically reduced in the Cu₂Te_0.8Se_0.2 sample is to be 9.99 × 10^–5 Ωm. The Seebeck coefficient value increases at a higher (x = 0.2) content 159.24 µV/K compared to other samples. Higher power factor was achieved in the (x = 0.2) sample values of 220 µW K⁻² m⁻¹ at 673 K. Cu₂Te_0.8Se_0.2 sample show relatively high figure of merit (zT) of 0.295 at 673 K, compared to other samples.