Effects of Processing Parameters on Thermoelectric Properties of n-Type Bi2Te2.3Se0.7 Thermoelectric Materials

In this study, the effects of different powder metallurgy processing routes on the thermoelectric properties of n-type Bi 2 Te 2 .3 Se₀.₇alloys were systematically investigated.Three powder metallurgy processes were used in this study: (A) ball milling followed by spark plasma sintering (SPS), (B) ball milling combined with vacuum induction melting (VIM) prior to SPS, and (C) ball milling -VIM -ball milling and finally SPS.The effect of an SPS pressure of 50 MPa on the thermoelectric performance was also evaluated.Among all the processing conditions, Process A combined with an SPS pressure of 50 MPa resulted in the highest thermoelectric performance.This processing route effectively preserved continuous carrier transport pathways while maintaining abundant grain boundaries and fine microstructural features, thereby enhancing phonon scattering and suppressing lattice thermal conductivity to approximately 0.45 W•m -1 •K -1 at 390 K. Consequently, the highest dimensionless figure of merit (ZT ≈ 0.81) was achieved at 390 K.These results demonstrate that optimizing the balance between electrical and thermal conductivities through appropriate processing parameters is critical for maximizing the thermoelectric efficiency of n-type Bi 2 Te 2.3 Se 0.7 alloys.