• Energy Research

AbstractThermoelectric materials are highly promising for waste heat harvesting. Although thermoelectric materials research has expanded over the years, bismuth telluride‐based alloys are still the best for near‐room‐temperature applications. In this work, a ≈38% enhancement of the average ZT (300−473 K) to 1.21 is achieved by mixing Bi0.4Sb1.6Te3 with an emerging thermoelectric material Sb2Si2Te6, which is significantly higher than that of most BiySb2−yTe3‐based composites. This enhancement is facilitated by the unique interface region between the Bi0.4Sb1.6Te3 matrix and Sb2Si2Te6‐based precipitates with an orderly atomic arrangement, which promotes the transport of charge carriers with minimal scattering, overcoming a common factor that is limiting ZT enhancement in such composites. At the same time, high‐density dislocations in the same region can effectively scatter the phonons, decoupling the electron‐phonon transport. This results in a ≈56% enhancement of the thermoelectric quality factor at 373 K, from 0.41 for the pristine sample to 0.64 for the composite sample. A single‐leg device is fabricated with a high efficiency of 5.4% at ΔT = 164 K further demonstrating the efficacy of the Sb2Si2Te6 compositing strategy and the importance of the precipitate‐matrix interface microstructure in improving the performance of materials for relatively low‐temperature applications.

Achieving high electronic mobility and excellent thermoelectric performance in GeTe through Ge vacancy suppression and band structure engineering.

Two-step sintering efficiently enhances zT by tuning the microstructure in a wide range from atomic defects to micrometer second phase.

Na+ diffuses and re-dissolves into matrix grains, resulting in carrier concentration modulation and thereby superior high temperature TE performances.

This review summarizes the crystal structures, microstructures, electronic structures, physical/chemical properties, and effective methods to enhance the thermoelectric performance of the BiCuSeO system.

Introducing local structural heterogeneity can be a feasible way to achieve a high and thermally stable piezoelectric response in lead-free piezoelectrics.

Nanopores with modified surfaces introduced by simultaneously adding BiI3 and Zn significantly improved the ZT value of (Bi,Sb)2Te3.

The structural origin of enhanced piezoelectric performance and stability in KNN-based ceramics can be attributed to the hierarchical nanodomain architecture with phase coexistence.

This work revealed that BiCuSeO oxyselenide is a potential oxide-based thermoelectric material, whose dimensionless figure of merit (ZT) reaches ∼0.70 at 773 K. High phase-purity BiCuSeO polycrystalline materials with fine grains were synthesized by a facile method combining a solid-state reaction and spark plasma sintering. Purifying the constitutive phase and reducing the grain sizes by introducing a high-energy ball milling process before spark plasma sintering were found to be effective in property enhancement. The resultant single-phased BiCuSeO sample derived from ball-milled powders shows good electrical conductivity above 4.0 × 103 S m−1 and a large Seebeck coefficient above 200 μV K−1. This compound has a low thermal conductivity (∼0.5 W m−1 K−1), which is associated with its low phonon transport speed and Young's modulus. Results indicated that BiCuSeO-based materials are promising for energy conversion applications in the moderate temperature range.