Synthesis and Thermoelectric Properties of TiO2/Cu2SnSe3 Composites

Thermoelectric (TE) materials are a kind of energy material which can directly convert waste heat into electricity based on TE effects. Ternary Cu2SnSe3 material with diamond-like structure has become one of the potential TE materials due to its low thermal conductivity and adjustable electrical conductivity. In this study, the Cu2SnSe3 powder was prepared by vacuum melting-quenching-annealing-grinding process. The nano-TiO2 particles were introduced into the Cu2SnSe3 matrix by ball milling. Spark plasma sintering (SPS) was employed to fabricate the TiO2/Cu2SnSe3 composites. The X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM) were used to study the phase and microstructure of TiO2/Cu2SnSe3 composites. Electrical resistivity, Seebeck coefficient, and thermal conductivity measurement were applied to analyze the thermoelectric properties. For the 1.4%TiO2/Cu2SnSe3 composite, the electrical conductivity was improved whereas the Seebeck coefficient was lower than that of pure Cu2SnSe3. For other TiO2/Cu2SnSe3 samples, the Seebeck coefficient was improved while the electrical conductivity was reduced. The thermal conductivity of TiO2/Cu2SnSe3 composites was lower than that of Cu2SnSe3 matrix, which is attributed to the lower carrier conductivity. A maximum ZT of 0.30 at 700 K for the 1.0%TiO2/Cu2SnSe3 composite was obtained, which was 17% higher than that of the pure Cu2SnSe3 at 700 K.