Facile rapid synthesis of a nanocrystalline Cu2Te multi-phase transition material and its thermoelectric performance

A highly efficient facile method was used to synthesize Cu2Te via spark plasma sintering (SPS) of high-energy ball-milled elemental powders, followed by annealing, which dramatically reduced the whole process time. The multiple phase transitions of Cu2Te over an extensive temperature range were determined using a combination of high temperature X-ray diffraction (HTXRD) and differential scanning calorimetry (DSC). This merit endows Cu2Te with the ability to trigger multiple critical scatterings from room temperature up to 900 K. Microscopic investigation showed that the Cu2Te prepared by this rapid method possesses tiny dispersive precipitates, with sizes in the range of 50-100 nm, that could serve as obstacles for the transfer of mid-wavelength phonons. As a result, a ZT value of similar to 0.52 at 1000 K was obtained for the sample annealed for 10 h after SPS.