Enhanced thermoelectric performance of n-type Si80Ge20P3-TiO2 composites

Thermoelectric materials, such as SiGe alloys, have gained significant attention for their application in electricity generation at high temperatures. However, improving the thermal and electrical transport properties of n-type SiGe remains a challenge. In this work, n-type Silicon-Germanium alloys (SiGe) with dispersed nano-TiO₂ particles (Si₈₀Ge₂₀P₃-x wt% nano-TiO₂, x = 0, 3, 4, 5, 6) were synthesized by ball milling followed by spark plasma sintering. The effects of nano-TiO₂ particles on the electrical and thermal transport properties were investigated. The power factor of n-type SiGe alloys dispersed nano-TiO₂ particles was slightly decreased. However, the thermal conductivity had a significant reduction because of enhanced phonon scattering resulted from the multi-dimensional defect features. Coherent interfaces formed between SiGe alloys and nano-TiO₂ particles can generate phonon scattering in the range of medium to long wavelength. A dimensionless figure-of-merit (zT) of 1.64 at 1073 K was obtained in the sample of Si₈₀Ge₂₀P₃-4 wt% nano-TiO₂, which is 40% higher than the Si₈₀Ge₂₀P₃ alloy. This work provides a new approach to optimizing the thermoelectric performance and promoting the potential applications.