Enhanced thermoelectric performance of n-type Si80Ge20P3-TiO2 composites

Abstract

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.