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Thermoelectric Peltier coolers (PCs) are being increasingly used as temperature stabilizers for optoelectronic devices. Increasing integration drives PC miniaturization, requiring thermoelectric materials with good strength. We demonstrate a simultaneous gain of thermoelectric and mechanical performance in (Bi, Sb)2Te3, and successfully fabricate micro PCs (2 × 2 mm2 cross-section) that show excellent maximum cooling temperature difference of 89.3 K with a hot-side temperature of 348 K. A multi-step process involving annealing, hot-forging and composition design, is developed to modify the atomic defects and nano- and microstructures. The peak ZT is improved to ∼1.50 at 348 K, and the flexural and compressive strengths are significantly enhanced to ∼140 MPa and ∼224 MPa, respectively. These achievements hold great potential for advancing solid-state refrigeration technology in small spaces. [ABSTRACT FROM AUTHOR]

The widespread application of thermoelectric (TE) technology demands high‐performance materials, which has stimulated unceasing efforts devoted to the performance enhancement of Bi2Te3‐based commercialized thermoelectric materials. This study highlights the importance of the synthesis process for high‐performance achievement and demonstrates that the enhancement of the thermoelectric performance of (Bi,Sb)2Te3 can be achieved by applying cyclic spark plasma sintering to BixSb2–xTe3‐Te above its eutectic temperature. This facile process results in a unique microstructure characterized by the growth of grains and plentiful nanostructures. The enlarged grains lead to high charge carrier mobility that boosts the power factor. The abundant dislocations originating from the plastic deformation during cyclic liquid phase sintering and the pinning effect by the Sb‐rich nano‐precipitates result in low lattice thermal conductivity. Therefore, a high ZT value of over 1.46 is achieved, which is 50% higher than conventionally spark‐plasma‐sintered (Bi,Sb)2Te3. The proposed cyclic spark plasma liquid phase sintering process for TE performance enhancement is validated by the representative (Bi,Sb)2Te3 thermoelectric alloy and is applicable for other telluride‐based materials. [ABSTRACT FROM AUTHOR]

P -type Bi 2-x Sb x Te 3 is one of the most mature and widely used thermoelectric (TE) materials. Enhancing its performance is important and has generated significant research attention, with studies ranging from chemical doping to various fabrication processes. In this work, we applied a method combining mechanical alloying and spark plasma sintering to synthesize Cu-doped Bi 0.3 Sb 1.7 Te 3. By adjusting the doping amount of Cu, the electrical conductivity and power factor were improved with a reduced lattice thermal conductivity, leading to a high dimensionless figure of merit (ZT) up to 1.32 at 400 K. This high performance could be maintained even after the sintered sample was subjected to a 100 A electric current pulse (ECP) at 523 K for 30 min, despite some slight changes in the electrical transport properties. Interestingly, it was found that the ECP treatment induced grain refinement and nanoscale inhomogeneity that reduced the lattice thermal conductivity, which canceled the negative effect on the ZT that had been caused by the slight decline in power factor. This work validated the effectiveness of Cu-doping for Bi 2-x Sb x Te 3 , and it also demonstrated a facile method for the stability study of thermoelectric materials. The ECP treatment was adopted as a facile method to investigate the migration of Cu ions in Cu-doped p -type (Bi,Sb) 2 Te 3 , which can additionally induce grain refinement and nanoscale inhomogeneities. Image 1 (1) 0.05 at.% Cu doping leads to >20% ZT increase in powder-processed Bi 0.3 Sb 1.7 Te 3. (2) The Cu-doped (Bi,Sb) 2 Te 3 can maintain its enhanced performance even after being subjected to a high electric current pulse. (3) ECP treatment induced grain refinement and nanoscale inhomogeneities that reduced the lattice thermal conductivity. [ABSTRACT FROM AUTHOR]

Bi 2 Te 3 -based materials have been widely used in thermoelectric conversion technologies. Thermoelectric modules are fabricated from Bi 2 Te 3 -based ingots, but utilization of recycled scraps produced during the machining of thermoelectric elements has attracted attention because of limited material resources. In this work, we proposed a strategy for reusing ingot scraps to produce practical high-performance thermoelectric materials via a spark plasma sintering process by adjusting the composition of the scraps. It was found that the SPS process with a transient liquid phase resulting from excess added Te enhanced the thermoelectric performance, and a appropriately long soaking time was needed for SPS to maximize this enhancement. A longer sintering time helped improve the electrical transport properties, while simultaneously reducing the lattice thermal conductivity. Eventually, the highest ZT value of 1.33 and maximum conversion efficiency of 4.2% were obtained in the sample sintered for 15 min. This work provides an effective strategy for recycling industrial scraps of Bi 2 Te 3 -based thermoelectric materials and demonstrates the importance of soaking time optimization when spark plasma sintering is used for re-processing. Liquid Te-assisted sintering effectively enhances the thermoelectric performance of Bi-Sb-Te materials based on the recycled commercial ingot scraps. The enhancement can be further maximized by appropriately prolonging the sintering time which leads to large grains and abundant dislocations. [Display omitted] • High TE performance Bi-Sb-Te materials can be obtained by reusing the ingot scraps via liquid-assisted sintering. • The enhancement of TE performance can be maximized by appropriately prolonging the sintering time. • The present long time sintering can boost the ZT value and conversion efficiency up to 1.33 and 4.2%, respectively. [ABSTRACT FROM AUTHOR]