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

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.

Bismuth telluride‐based materials are already being commercially developed for thermoelectric (TE) cooling devices and power generators. However, the relatively low efficiency, which is characterized by a TE figure of merit, zT, is the main obstacle to more widespread application. Significant advances in the TE performance have been made through boundary engineering via embedding nanoinclusions or nanoscale grains. Herein, an effective approach to greatly enhance the TE performance of p‐type BiSbTe material by incorporating carbon microfibers is reported. A high zT of 1.4 at 375 K and high average zT of 1.25 for temperatures in the range of 300 to 500 K is achieved in the BiSbTe/carbon microfiber (BST/CF) composite materials. Their superior TE performance originates from the low thermal conductivity and the relatively high power factor. A TE unicouple device based on the p‐type BST/CF composite material and the commercially available n‐type bismuth telluride‐based material shows a huge cooling temperature drop in the operating temperature range of 299–375 K, and is greatly superior to the unicouple device made of both commercial p‐type and n‐type bismuth telluride‐based material. The materials demonstrate a high average zT and excellent mechanical properties and are strong candidates for practical applications.

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trical conductivity, S is Seebeck coefficient, T is the absolute temperature, and κ is the thermal conductivity (κ = electronic (κ e) + lattice thermal conductivity (κ L)). [2,3] The state-of-the-art bismuth telluride-based thermoelectric (TE) materials have been used for refrigeration applications. [4] However, their ZT is limited to about 1 at room temperature, making such cooling devices less powerful and cost-competitive than other conventional technologies such as mechanical vapor-compression cooling systems. Further improving the ZT would facilitate their widespread application in industrial waste heat harvesting and electronic device cooling. [5] Maximizing ZT requires the enhancement of the power factor (PF = S 2 σ) and the reduction of thermal conductivity. [6,7] Several approaches have recently been implemented to enhance ZT, including improvement of PF by optimizing carrier concentration, [8-10] band convergence, [11,12] resonant levels, [13] energy barrier filtering, [14] and reducing κ L by alloying, [15] all-scale hierarchical architectures [16-18] and nanostructuring. [19-21] In particular, reduction of κ L by nanostructuring or through formation of nanocomposites has been demonstrated to be an effective Based on the Seebeck and Peltier effects, state-of-the-art bismuth telluridebased thermoelectric materials, which are capable of direct and reversible conversion of thermal to electrical energy, have great potential in energy harvesting and solid-state refrigerators. However, their widespread use is limited by their low conversion efficiency, which is determined by the dimensionless figure-of-merit (ZT). Significant enhancement of ZT is a great challenge owing to the common interdependence of electrical and thermal conductivity. Here, it is demonstrated that by incorporating nanoamorphous boron into the p-type Bi 0.5 Sb 1.5 Te 3 , a record high ZT of 1.6 at 375 K is achieved. It is shown that a high density of nanostructures and dislocations due to the incorporation of the boron inclusions, leads to a significant reduction of thermal conductivity and improved charge transport. The findings represent an important step to further promote the development of thermoelectric technology and its widespread application in solid-state refrigeration and power generation from waste heat.

Peltier devices utilizing thermoelectric (TE) materials are expected to be used for precise temperature management in 5G and next-generation communication technologies. This demand has driven efforts to develop high-TE-performance Bi2Te3-based...

A series of single-phased Cu2S1−xSex bulks were prepared by using mechanical alloying (MA) combined with spark plasma sintering (SPS). Our results suggest that the TE properties of Cu2S can be greatly enhanced by simultaneously increasing PF and decreasing κ via doping a sole Se element.

The influence of metal vapour on the arc behaviour during the arc-splitting process in the quenching chamber of a low-voltage circuit breaker is investigated numerically. A three-dimensional magnetohydrodynamic model of air arc plasma, taking into account the production of metal vapour from erosion of an iron splitter plate, is developed. An equation describing conservation of the iron vapour mass is added to the standard mass, momentum and energy conservation equations. The influence of the iron vapour on the thermodynamic and transport properties of the gas mixture is considered. The arc voltage, distributions of temperature, gas flow and mass fraction of iron vapour in the arc chamber are calculated. The formation of new arc roots on the splitter plate is examined. The simulation results indicate that this is strongly influenced by the presence of iron vapour from the splitter plate, due to the increased electrical conductivity in the arc root formation region. The consequences of this are dramatic. The presence of metal vapour causes the arc to attach first to the cathode side of the splitter plate, and electromagnetic forces then cause the arc on this side to move more rapidly than the arc on the anode side. The opposite occurs if metal vapour is neglected. High-speed photography of arc motion is used to confirm the arc motion predicted in the presence of metal vapour. Further, the calculated arc voltage taking into account metal vapour is lower than that calculated neglecting metal vapour, because of the increased electrical conductivity, and agrees much better with the measured voltage.