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Bismuth telluride-based materials are well known for their excellent thermoelectric (TE) properties within the near-room temperature range. However, the poor thermoelectric performance of their n-type counterparts has posed a major hindrance to the application of bismuth telluride-based thermoelectric generator (TEG). In this study, a dual optimization approach was implemented. Specifically, 2D ceramic nano-sized hexagonal boron nitride (h-BN) was introduced into n-type Bi 2 Te 2.7 Se 0.3 (BTS) to enhance its performance, aligning it with p-type materials. It is indicated that ceramic h-BN decoration leads to the emergence of a high density of dislocations, which boosts the phonon scattering and reduces lattice thermal conductivity significantly. Meanwhile, a high carrier mobility is maintained to ensure an improved power factor. With the addition of moderate ceramic h-BN, the composite material achieved a ZT value of 1.1 at 400 K. The geometric configuration of TEG was optimized using finite element methods to strike the optimal balance between output power (P o u t ) and efficiency (η). Based on the structure optimization results, the predicted P o u t and η increased by 48 % and 36 %, respectively. The fabricated TEG demonstrated to achieve an efficiency of 6.4 %. This work allows the evolution from bismuth telluride-based prototype to a functional TEG advanced in room-temperature heat recovery. [ABSTRACT FROM AUTHOR]

Due to their superior thermoelectric capabilities, Bi 2 Te 3 -based materials have long been a popular area of study in the thermoelectric field. However, further advancements in the energy conversion efficiency of Bi 2 Te 3 -based thermoelectric modules are constrained by the low figure of merit of n -type Bi 2 Te 3. Here, we describe an efficient method for enhancing the electrical and thermal characteristics of n -type Bi 2 Te 2.7 Se 0.3 (BTS) material by dispersing TiO 2 ceramic nanoparticles (NPs) in the matrix of the BTS. In more detail, the energy potential barrier, created by the matrix and the addition of TiO 2 NPs, causes an energy filtering effect, which in turn raises the Seebeck coefficient. The lattice thermal conductivity is decreased as a result of dislocations at the TiO 2 /BTS interface and an increase in grain boundary density brought on by the fine grain strengthening of TiO 2 ceramic NPs. Last but not least, the ZT max for the BTS + 3 wt% TiO 2 sample increased to 1.31, representing an improvement of 52% over the pristine sample. Additionally, at a maximum temperature differential of 150K, we have built a thermoelectric module with a power output and energy conversion efficiency of 7.2 W and 5.9%, respectively. This study introduces a viable approach towards the rational design of advanced n -type Bi 2 Te 2.7 Se 0.3 materials. [ABSTRACT FROM AUTHOR]

Bismuth telluride (Bi 2 Te 3)-based thermoelectric materials have been commercially utilized for refrigeration and energy conversion at room/near room temperature. However, n -type Bi 2 Te 3 compounds always exhibit inferior performance compared with their p-type counterparts, which is pronouncedly impeding Bi 2 Te 3 -based energy converters from further optimizations. Herein, a promising ZT value (ZT = 1.33) was obtained in n-type Bi 2 Te 2.7 Se 0.3 (BTS) materials by using an interface engineering strategy to synergistically optimize the electron and phonon transport properties. In detail, ZrO 2 ceramic nanoparticles (NPs) were entered into BTS matrix to construct high-density heterogeneous interfaces. The heterogeneous interfaces strongly scatter phonons and lower energy carriers, leading to decreased thermal conductivity and increased Seebeck coefficient, while the electrical conductivity is not sacrificed due to the compromise of the slightly reduced carrier mobility by interfacial scattering and the increased carrier concentration by ZrO 2 NPs doping. A planar module consisting of 127 pairs of p-n single legs were assembled. At the temperature difference of 200 K, the output power and energy conversion efficiency reached 9.6 W and 6.2%, respectively. This strategy provides a feasible way to rationally design advanced n-type Bi 2 Te 2.7 Se 0.3 materials with excellent thermoelectric and mechanical properties induced by high-density heterogeneous interfaces. [ABSTRACT FROM AUTHOR]

The performance of n-type Bi 2 Te 3 materials prepared by selective laser melting (SLM) 3D printing technology tends to be lower than p-type materials. Herein, a bottom-up interface engineering strategy based on Atomic Layer Deposition (ALD) is presented to improve the properties of n-type Bi 2 Te 2.7 Se 0.3 (BTS) materials prepared by SLM. To validate this strategy, a ZnO ultrathin layer was applied to the grain boundaries of BTS, synergistically optimizing carrier/phonon transport. In terms of electrical transport, the energy filtering effect triggered by the constructed ZnO/BTS interface effectively enhances the Seebeck coefficient of the Bi 2 Te 3 material printed by SLM, substantially increasing the power factor. Additionally, the high thermal stability of the ALD-deposited ZnO ultrathin layer effectively suppresses the volatilization of Te in BTS, regulating the carrier concentration. Regarding thermal transport properties, the multiscale defects introduced by the non-equilibrium solidification process during SLM printing cause effective phonon scattering across a wide frequency range, which in turn reduces the thermal conductivity of the material. Atomic-level interface modification in SLM-printed BTS enhanced the ZT value to 1.25. Exploiting this superior thermoelectric performance, a thermoelectric module was constructed. It demonstrated a conversion efficiency of 5.7 % with a temperature difference of 200 K, comparable to the advanced Bi 2 Te 3 -based thermoelectric modules. The integration of an ALD interface modification strategy with SLM technology has not only demonstrated potential applications in Bi 2 Te 3 -based thermoelectric material development, but also bears significant importance for the accelerated advancement of high-performance thermoelectric materials in other systems. • Atomic interface engineering modulates electro-thermal transport in 3D printed n-Bi 2 Te 2.7 Se 0.3. • Adjustable ZnO layer thickness controls ZnO/BTS composition and structure at the atomic level. • Optimized ZnO/BST samples show high power factor, strong phonon scattering, and ZT~1.25 at 373 K. • The thermoelectric module achieves 5.7% conversion efficiency with a 200 K temperature difference. [ABSTRACT FROM AUTHOR]

Thermoelectric generators held great promise through energy harvesting from waste heat. Their practical application, however, is greatly constrained by poor raw material utilization and tedious processing in fabricating desired shapes. Herein, a state‐of‐the‐art process is reported for 3D printing the half‐Heusler (Nb0.88Hf0.12FeSb) thermoelectric material using laser powder bed fusion (LPBF). The multi‐dimensional intra‐ and inter‐granular defects created by this process greatly suppress thermal conductivity by providing numerous phonon scattering centers. The resulting LPBF‐fabricated half‐Heusler exhibits a high figure of merit ≈1.2 at 923 K and a single‐leg maximum efficiency of ≈3.3% at a temperature difference (ΔT) of 371 K. Hafnium oxide nanoparticles generated during LPBF effectively prevent crack propagation, ensuring competent mechanical performance and reliable thermoelectric output. The findings highlight the significant potential of LPBF in driving the next industrial revolution of highly efficient and customizable thermoelectric materials. [ABSTRACT FROM AUTHOR]

Rational design of microstructure in thermoelectric materials is conducive to improve the thermoelectric properties. Bismuth telluride alloys are easy to form texture during sintering due to the weak van der Waals bonding between the Te-Te layers. However, high content of texture will greatly deteriorate the out-of-plane electrical properties and in-plane thermal properties. Herein, the bulk sample of n-type Bi 2 Te 2.7 Se 0.3 with controllable texture degree was obtained by selective laser melting (SLM) 3D printing technology. By setting the appropriate laser power density, the epitaxial growth of some grains in the melt pool can be suppressed and controlled texturing of the material can be achieved. The printed Bi 2 Te 2.7 Se 0.3 alloy shows texture-dependent thermoelectric properties by texture control ensuring that the Bi 2 Te 2.7 Se 0.3 alloy has both high carrier mobility and strong phonon scattering, leading to a competitive ZT ∼ 1.21 at 373 K. Based on excellent thermoelectric properties, we have assembled a 127-pair thermoelectric module with a conversion efficiency of 6.2 % at a temperature difference of 213 K, and the corresponding output performance is comparable to that of state-of-art bismuth telluride thermoelectric modules. This study illustrates the potential of texture engineering based on SLM printing in developing high-performance thermoelectric materials. • Linking selective laser melting 3D printing with texture engineering to manipulate the thermoelectric properties. • Achieving texture-degree-control by 3D printing to optimize the thermoelectric performance of Bi 2 Te 2.7 Se 0.3 materials. • The texture-controlled Bi 2 Te 2.7 Se 0.3 alloy has a competitive ZT ∼1.21 at 373 K. • The assembled state-of-art bismuth telluride TE module has a high energy conversion efficiency ∼ 6.2 %. [ABSTRACT FROM AUTHOR]

Plasma-facing components (PFCs) have consistently been one of the most crucial elements in modern magnetic confinement nuclear fusion devices. However, conventional metallurgical fabrication methods struggle to achieve the integral shaping of complex structures, and the control of interface strength is another challenging of its own. Additive manufacturing is a highly promising approach capable of achieving one-time forming of various intricate structures. In this study, the structurally optimized tungsten-Reduced Activation Ferritic/Martensitic (RAFM) steel PFCs were prepared using Selective Laser Melting (SLM) technology. Subsequently, the performance of the PFCs was analyzed through thermal fatigue load tests, thermodynamic simulations, and micro-mechanical experiments. The research revealed that the hypervapotron structure can reduce temperatures by >20.6 % compared to circular tubular cooling structures. Simultaneously, direct bonding between tungsten and steel was achieved through additive manufacturing technology. Elements (Fe, W, Cr, C, etc.) could undergo mutual diffusion, gradually reducing the mechanical properties of the interface under thermal loads. Furthermore, stress concentration and thresholds (from 1.18 GPa to 1.59 GPa) were identified on the interface, and cracking occurred when the tensile strength on the interface fell below this value. This indicates that the PFCs module directly connected with W/RAFM by additive manufacturing can withstand a limited cycles of 5 MW/m² fatigue thermal shocks. But if by adding some interlayer elements to prevent the mutual diffusion, mitigate the structural softening effect caused by thermal fatigue, and relieve the interfacial stress, which would mitigate this problem, and should be one of the next development directions for the PFCs fabricated by additive manufacturing. This work provides crucial references for the development of future PFCs. [ABSTRACT FROM AUTHOR]