High thermoelectric performance of In-doped Cu2SnSe3 prepared by fast combustion synthesis

Abstract

Bulk In-doped Cu₂SnSe₃ samples have been prepared by a fast, one-step method combining the synthesis and sintering process, named high-pressure combustion synthesis (HPCS), and they were also prepared by conventional spark plasma sintering (SPS) for comparison. The relative densities of the In-doped Cu₂SnSe₃ samples are above 98%, a little higher than the 96% by SPS. The thermodynamic parameters and reaction kinetics of the HPCS process are investigated, showing the maximum combustion temperature of 708 K and combustion wave propagation velocity of 2 mm s⁻¹. The thermoelectric properties of the Cu₂Sn_1−xIn_xSe₃ samples (HPCS) with x ranging from 0 to 0.20 have been measured in the temperature range of 323–773 K. The electrical conductivity at 323 K is greatly enhanced by almost 6 times from 2.2 × 10⁴ S m⁻¹ to 12.9 × 10⁴ S m⁻¹ by the substitution of Sn with In (x = 0.15). The maximum ZT reaches 0.56 at 773 K for the sample of x = 0.10, which is about 20% higher than that of the unadulterated sample. Compared with the samples prepared by HPCS-SPS, the maximum ZT reaches 1.28 at 823 K for the In doping content of x = 0.10, which is much higher than that for the HPCS samples, attributing to the much lower thermal conductivity caused by strong boundaries scattering. The combustion synthesis offers a fast and more efficient approach for the fabrication of Cu₂SnSe₃ materials with reduced time and energy consumption.