Incorporation of Ni in Cu₂SnSe₃: An insight into the reduction in electrical resistivity

In the present study, Cu₂SnSe₃/x% Ni (x = 0, 1, 2 and 3 wt%) composite thermoelectric were synthesized using solid-state reaction followed by sintering in the mid-temperature range 300-570 K. XRD studies revealed that the samples have a diamond cubic structure with the F 4 ¯ 3 m space group. Scanning Electron Microscopy indicates that the synthesized samples possess homogeneous surfaces with fewer pores. The sample with 3% Ni exhibits an approximately eight-fold increase in electrical conductivity than the pure sample at 307 K. However, the addition of Ni decreased the Seebeck coefficient, resulting in a lower overall power factor (PF) for the composites. The highest PF of ∼420 μW/mK², was observed in the pristine sample at 570 K. Although Ni addition improves electrical properties, it negatively impacts the overall thermoelectric performance due to the significant reduction in Seebeck coefficient, thereby lowering the overall power factor.