Enhanced thermoelectric properties of p-type Bi 0.5 Sb 1.5 Te 3 bulk alloys by electroless plating with Cu and annealing (original) (raw)
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In this research, the microstructure and transport properties of p-type Bi 0.5 Sb 1.5 Te 3 thermoelectric materials were investigated as a function of milling time. The p-type Bi 0.5 Sb 1.5 Te 3 alloys were fabricated by mechanical alloying of elemental chunks of bismuth, antimony, and tellurium. This was followed by plasma spark sintering at 673 K. The micro-Vickers hardness (98.7 Hv) was considerably improved in the 90-min sample due to the presence of fine grains in the matrix that prevented crack propagation via grain-boundary hardening. The lowest lattice thermal conductivity (0.63 W/mK) was obtained for the 90-min sample, a value slightly lower than the minimum total thermal conductivity (0.872 ± 0.5 W/mK at 300 K) due to strong scattering of phonons and carriers owing to the completely randomness of the distribution of the fine-grain structure in the bulk samples. The maximum figure-of-merit (ZT = 0.98 ± 0.5 at 300 K) was obtained for the 90-min sample due to its superior power factor values.
Herein, we report our work on large-scale production (2 kg/min) of BiSbTe alloy powders by gas at-omization and spark-plasma sintering. We tried to optimize the fundamental transport parameters (carrier concentration, mobility, effective mass, and thermal conductivity) for improved thermoelectric performance of p-type Bi 2 Te 3 by selecting different size ranges of powder particles. The Seebeck coefficient values were greatly enhanced (by 52%) due to increase in effective mass, and thermal conductivity was decreased (by 36%) using the <30 mm powder spark-plasma sintered sample (compared with GA sample) due to phonon scattering at the grain boundary. However, the 32e75 mm powder is preferable for attaining a high ZT value due to its high thermoelectric quality factor (b). The highest ZT value obtained was 1.23 at 350 K for the 32e75 mm powder bulk samples. This was an improvement of ~23% compared to the GA sample. The average ZT av of 1.15 in the temperature range 300e400 K, enables the alloy to be suitable for low temperature applications.
Enhanced Thermoelectric Properties of p-Type Bi0.5Sb1.5Te3-Cu8GeSe6 Composite Materials
ACS Applied Materials & Interfaces, 2022
Copper coated Bi 0.5 Sb 1.5 Te 3 powders were prepared through electroless plating with simplified pretreatment method. After hydrogen reduction, the powders are consolidated into bulk by spark plasma sintering. The lowest lattice thermal conductivity in Bi 0.5 Sb 1.5 Te 3 /Cu reduces to 0.25 W/m•K at 371.5 K after annealing. The figure of merit (ZT) of Bi 0.5 Sb 1.5 Te 3 /Cu ascends in a large scale and reaches 1.08 at 373 K and 423 K before and after annealing respectively. The average ZT values of Bi 0.5 Sb 1.5 Te 3 /Cu samples both rise from 0.36 to 0.82, which makes this material suitable for application in a wide temperature range.
Journal of Electronic Materials, 2018
Bi 2 Te 3) x À (Sb 2 Te 3) 1Àx alloys with high thermoelectric properties were fabricated for waste heat energy recovery by mechanical alloying followed by spark plasma sintering. The samples' diffraction peaks, such as the (015) positions, were slightly shifted from high to low 2h angles with decreasing Sb 2 Te 3 content due to the occupation of Sb sites by Bi atoms in the crystal lattice. The electrical conductivity increased with (Sb 2 Te 3) content due to an increase in carrier concentration. The sample with the nominal composition of (Bi 2 Te 3) 0.15 + (Sb 2 Te 3) 0.85 exhibited a maximum thermoelectric figure of merit, ZT of 1.3 ± 0.06 at 400 K, and 1.07 ± 0.06 at 300 K. This enhanced ZT was successfully achieved by increasing (Sb 2 Te 3) content, which reduces intrinsic conduction at higher temperatures by increasing carrier concentration and band gaps. The enhanced thermoelectric performance of the (Bi 2 Te 3) 0.15 + (Sb 2 Te 3) 0.85 TE materials can provide exceptional benefits for power generation and cooling applications around 400 K.
Nano Letters, 2010
Herein, we report the synthesis of multiscale nanostructured p-type (Bi,Sb) 2 Te 3 bulk materials by melt-spinning single elements of Bi, Sb, and Te followed by a spark plasma sintering process. The samples that were most optimized with the resulting composition (Bi 0.48 Sb 1.52 Te 3 ) and specific nanostructures showed an increase of ∼50% or more in the figure of merit, ZT, over that of the commercial bulk material between 280 and 475 K, making it suitable for commercial applications related to both power generation and refrigeration. The results of high-resolution electron microscopy and small angle and inelastic neutron scattering along with corresponding thermoelectric property measurements corroborate that the 10-20 nm nanocrystalline domains with coherent boundaries are the key constituent that accounts for the resulting exceptionally low lattice thermal conductivity and significant improvement of ZT.
In this work, we fabricated Bi 0.5 Sb 1.5 Te 3 thermoelectric alloys using the mass-production technique, and subsequently Fe 2 O 3 and Fe-85Ni alloy nanoparti-cles were dispersed in the matrix by high energy ball milling and consolidated using spark plasma sintering technique. The influence of Fe 2 O 3 and Fe-85Ni alloy spherical nanoparticles in Bi 0.5 Sb 1.5 Te 3 (BST) matrix on thermoelectric transport properties has been investigated. The x-ray diffraction and scanning electron microscopy results show that the nanoparticles were dispersed in the matrix. The spark plasma sintered bulk BST/Fe 2 O 3 composite sample exhibited high Seebeck coefficient which was 39% higher than the bare BST due to low carrier concentration and a significant reduction in the thermal conductivity (38%) owing to enhanced carrier scattering by the dispersed nanopar-ticles compared to that of the bare BST sample. As a result, the maximum ZT values for the BST, BST/Fe 2 O 3 , and BST/Fe-85Ni samples were found as 1.17, 0.98, and 0.88 at 375 K, respectively. Micro Vickers hardness of BST/Fe 2 O 3 and BST/Fe-85Ni composite samples was significantly enhanced compared to bare Bi 0.5 Sb 1.5 Te 3 sample.
Bismuth telluride has already been utilized as a thermoelectric material near room temperature for a long time. Higher mechanical strength is still needed in order to prevent unexpected cleavage during manufacturing process of modules, and a further improvement in thermoelectric performance is also longed. For a high-performance thermoelectric material, a fine-grained microstructure is desirable owing to low thermal conductivity as well as high strength and toughness. We focused on the effectiveness of a combination of mechanical alloying (MA) process of starting materials and subsequent hot-extrusion process. The bulk extrudates of p-type Bi0.4Sb1.6Te3 compound have sound appearances, high density, fine-grained microstructures with single phase and also the enhanced thermoelectric performance. As a result, a significant improvement in both thermoelectric and mechanical performances of p-type Bi0.4Sb1.6Te3 compounds was obtained by the combination of MA process of starting materials...
Archives of Metallurgy and Materials
The dispersion of nanoparticles in the host matrix is a novel approach to enhance the thermoelectric performance. In this work, we incorporate the TiC (x = 0, 1 and 2 wt.%) nanoparticles into a p-type Bi 0.5 Sb 1.5 Te 3 matrix, and their effects on microstructure and thermoelectric properties were systematically investigated. The existence of TiC contents in a base matrix was confirmed by energy dispersive X-ray spectroscopy analysis. The grain size decreases with increasing the addition of TiC content due to grain boundary hardening where the dispersed nanoparticles acted as pinning points in the entire matrix. The electrical conductivity significantly decreased and the Seebeck coefficient was slightly enhanced, which attributes to the decrease in carrier concentration by the addition of TiC content. Meanwhile, the lowest thermal conductivity of 0.97 W/mK for the 2 wt.% TiC nanocomposite sample, which is ~16% lower than 0 wt.% TiC sample. The maximum figure of merit of 0.90 was obtained at 350 K for the 0 wt.% TiC sample due to high electrical conductivity. Moreover, the Vickers hardness was improved with increase the addition of TiC contents.
2019
The dispersion of nanoparticles in the host matrix is a novel approach to enhance the thermoelectric performance. In this work, we incorporate the TiC (x = 0, 1 and 2 wt.%) nanoparticles into a p-type Bi0.5Sb1.5Te3 matrix, and their effects on microstructure and thermoelectric properties were systematically investigated. The existence of TiC contents in a base matrix was confirmed by energy dispersive X-ray spectroscopy analysis. The grain size decreases with increasing the addition of TiC content due to grain boundary hardening where the dispersed nanoparticles acted as pinning points in the entire matrix. The electrical conductivity significantly decreased and the Seebeck coefficient was slightly enhanced, which attributes to the decrease in carrier concentration by the addition of TiC content. Meanwhile, the lowest thermal conductivity of 0.97 W/mK for the 2 wt.% TiC nanocomposite sample, which is ~16% lower than 0 wt.% TiC sample. The maximum figure of merit of 0.90 was obtained...