Enhanced Thermoelectric Performance in n-Type SrTiO₃/SiGe Composite

Abstract

Silicon germanium (SiGe) alloys hold promise for thermoelectric power generation at high temperatures and have been applied in deep-space missions. However, enhancement of the dimensionless thermoelectric figure-of-merit (ZT) is still needed for practical civil applications of SiGe. In this work, we report high-performance oxide/SiGe bulk composites that were obtained via hot-press sintering of mixed powders composed of phosphorus (P)-doped SiGe prepared via mechanical alloying, using a ball-milling technique and La−Nb-doped SrTiO 3 (La−Nb−STO). The La− Nb−STO powder was obtained from ball milling of a bulk La−Nb−STO sample that was sintered via hot pressing of hydrothermally synthesized La−Nb−STO powder. Controlling the amount of La−Nb−STO nanoparticles added to SiGe matrix increased the power factor by optimizing the electron concentration and mobility in the composite. In addition, compared with single-phase P-doped SiGe, the second phase decreased the thermal conductivity because of additional phonon scattering at the interface. As a result, a high ZT of 0.91 was realized in the n-type oxide/SiGe bulk composite at 1000 K, which was 18% larger than that for the typical materials used in space flight missions and 5% higher than the single-phase SiGe alloys obtained in the present study. The strategy used in this study could also be viable to further enhance the ZT of nanostructured n-type SiGe and SrTiO 3 -based oxide materials.

Prelithiation/Presodiation Techniques for Advanced Electrochemical Energy Storage Systems: Concepts, Applications, and Perspectives

“…In terms of electrode materials, prelithiation/presodiation could optimize their structures and improve electrochemical performances. [ 155–158 ] Zhu et al synthesized the prelithiated surface oxide layer (Li 2 SiO 3 ) to enable the high‐performance Si anode for lithium storage ( Figure a). [ 159 ] Significantly, the elaborated coating layer could strengthen integrity of electrode, suppress irreversible reactions, and supply efficient Li + diffusion channels.…”

Ultra-low thermal conductivity in B2O3 composited SiGe bulk with enhanced thermoelectric performance at medium temperature region

“…23 Sajid Ahmad et al, by mixing titanium dioxide nano-inclusions into P-type of SiGe-based TE materials, signicantly enhanced the thermoelectric performance and obtained a ZT value of 1.3 at 1000 K. 24 Jun Wang et al also obtained a high ZT value of 0.91 at 1000 K by combining strontium titanate particles in N-type silicon and germanium. 25 As mentioned above, the composite of nano-sized oxide particles with low thermal conductivity in the SiGe bulk can suppress the thermal conductivity signicantly, but there is also the risk of a signicant reduction in the conductivity and power factor. Therefore, the choice of composite oxides in SiGe is highlighted.…”

Thermoelectric enhancement of p-type Si 80Ge 20 alloy via co-compositing of dual oxides: Respective regulation for power factor and thermal conductivity by β-Ga 2O 3 and SiO 2 aerogel powders

“…Besides, the reduced a v indicated the weakened bonds via compositing of amorphous SiO 2 inclusions. The  of 2.38 W•m −1 •K −1 was achieved, which is significantly dropped by 32.6% in contrast to that of the pristine p-type SiGe counterpart; and the ZT of 0.9 was achieved at 600 ℃, which is better than those of most corresponding oxide-composited Si-based bulks [24,26,27,49]. Our scenario of dual-oxide composition provides a novel and green pathway for the enhancement of Si-based TE materials, which possesses prominent implications for clearly developing sustainable energy in the not-toodistant future.…”