Enhancement in the Figure of Merit of p-type BiSb alloys through multiple valence-band doping (original) (raw)
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Enhancement in the figure of merit of p-type Bi100−xSbx alloys through multiple valence-band doping
Applied Physics Letters, 2012
High temperature Z-meter setup for characterizing thermoelectric material under large temperature gradient Rev. Sci. Instrum. 83, 075117 (2012) Zn migration during spark plasma sintering of thermoelectric Zn4Sb3 Appl. Phys. Lett. 101, 043901 (2012) Electronic structure and thermoelectric properties of nanostructured EuTi1−xNbxO3−δ (x=0.00; 0.02) Appl. Phys. Lett. 101, 033908 Electrical and thermoelectric properties of single-wall carbon nanotube doped Bi2Te3 Appl. Phys. Lett. 101, 031909 Large thermoelectric power factor in p-type Si (110)/[110] ultra-thin-layers compared to differently oriented channels N-type Bi 100Àx Sb x alloys have the highest thermoelectric figure of merit (zT) of all materials below 200 K; here, we investigate how filling multiple valence band pockets at the T and H-points of the Brillouin zone produces high zT's in p-type Sn-doped material. This approach, theoretically predicted to potentially give zT > 1 in Bi, was used in PbTe. We report thermopower, electrical and thermal conductivity (2 to 400 K) measurements of single crystals with 12 x 37 and polycrystals (x ¼ 50-90), higher Sb concentrations than previous studies. We obtain a 60% improvement in zT to 0.13. V C 2012 American Institute of Physics.
High thermoelectric performance BiSbTe alloy with unique low-dimensional structure
Journal of Applied Physics, 2009
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RSC Advances, 2018
Bi 0.88Àx Zn x Sb 0.12 alloys with x ¼ 0.00, 0.05, 0.10, and 0.15 were prepared using hydrothermal synthesis in combination with evacuating-and-encapsulating sintering. The effects of partial Zn substitution for Bi and different sintering temperatures on the thermoelectric properties of Bi 0.88Àx Zn x Sb 0.12 alloys were investigated between 25 K and 425 K. Both the electrical conductivity and absolute thermopower are enhanced for the set of alloys sintered at 250 C. The maximum power factor of 57.60 mW cm À1 K À2 is attained for the x ¼ 0.05 alloy sintered at 250 C. As compared with Zn-free Bi 0.88 Sb 0.12 , both the total thermal conductivity and lattice component are reduced upon Zn doping. Bipolar conduction is observed in both electronic and thermal transport. The maximum zT of 0.47 is attained at 275 K for the x ¼ 0.05 alloy sintered at 250 C.
Journal of Materials Research and Technology, 2022
or thermal to electric energy conversion, designing a high efficiency thermoelectric material entails simultaneously optimizing multiple properties of the material. Although it may appear simple to increase electrical power while minimizing thermal losses, the complicated link between these parameters makes optimization difficult, necessitating a more sophisticated approach. The one-pot zone melting method was used to fabricate undoped and Sb doped Bi2Te3 (Bi2−xSbxTe3; x = 0.0, 0.2, 0.6, and 1.0) in pellets form. X-ray diffraction (XRD), Raman and selected area electron diffraction (SAED) revealed rhombohedral polycrystalline nature and a unique high intensity of the Eg2 optical mode according to the nanosheet nature of the alloys as observed in the scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images. Besides, High Resolution TEM (HRTEM) micrographs depicted twin boundary effect with an angle of 120° for Bi1.8Sb0.2Te3 alloys, which may enhance the electronic transport and the thermoelectric properties of the fabricated compounds. To obtain selective and detailed local structural information of Bi2−xSbxTe3 matrix, synchrotron radiation-based X-ray absorption spectroscopy (XAS) measurements were performed at around Bi L3-edge. A significant influence of the Sb/Bi substitution on the local/atomic structure was observed through the gradual elongation of the average in-plane Bi–Sb bond distance. The combination of different off-line structural characterization techniques such as XRD, Raman, SEM, and HRTEM with synchrotron based XAS technique and Laser-Beam Deflection Spectroscopy (BDS) is necessary to fully describe the samples nature and to get average crystal, morphological and local/electronic structural information for unveiling the BiSbTe mechanism in thermoelectric generation.
Thermal and electronic properties of Bi1−xSbx alloys
Journal of Alloys and Compounds, 2009
Polycrystalline Bi 1 − x Sb x (x = 0.10, 0.12 and 0.15) semiconducting alloys were synthesized by mechanical alloying in order to achieve homogeneous thermoelectric materials with improved mechanical strength. The homogeneity of the powder samples were repeatedly checked by X-ray diffraction and scanning electron microscopy to standardize the milling conditions. The best possible homogenized material was developed with the milling conditions of BPR 30:1, ball diameter 30 mm, 400 rpm and milling time of 15 h. The electrical resistivity, thermoelectric power and thermal conductivity were measured in the temperature range 300-500 K. It was found through these experiments that the composition with x = 0.12 behaved in a normal semiconducting way, whereas the other two compositions (x = 0.10 and 0.15) showed degenerate semiconductor behaviour. These features have been qualitatively explained from the band structure and interband scattering mechanisms.
Annalen der Physik, 2019
To achieve high-performance n-type PbTe-based thermoelectric materials, this work provides a synergetic strategy to improve electrical transport property with indium (In) element doping and reduces thermal conductivity with sulfur (S) element alloying. In n-type PbTe, In doping can tune the carrier density in the whole working temperature range, causing the carrier density to increase from 2.18 × 10 19 cm −3 at 300 K to 4.84 × 10 19 cm −3 at 823 K in Pb 0.98 In 0.005 Sb 0.015 Te. The optimized carrier density can further modulate electrical conductivity and Seebeck coefficient, finally contributing to a substantial increase of power factor, and a maximum power factor increase from 19.7 µW cm −1 K −2 in Pb 0.985 Sb 0.015 Te to 28.2 µW cm −1 K −2 in Pb 0.9775 In 0.0075 Sb 0.015 Te. Based on the optimally In-doped PbTe, S alloying is introduced to suppress phonon propagation by forming a complete solid solution, which could effectively reduce lattice thermal conductivity and simultaneously benefit carrier mobility to maintain high power factor. With S alloying, the minimum lattice thermal conductivity decreases from 0.76 Wm −1 K −1 in Pb 0.985 Sb 0.015 Te to 0.42 Wm −1 K −1 in Pb 0.98 In 0.005 Sb 0.015 Te 0.88 S 0.12. Combining the advantages of both In doping and S alloying, the peak ZT value and averaged ZT (ZT ave) (300-873 K) are boosted from 1.0 and 0.60 in Pb 0.985 Sb 0.015 Te to 1.4 and 0.87 in Pb 0.98 In 0.005 Sb 0.015 Te 0.94 S 0.06 .
Room temperature Bi2Te3-based thermoelectric materials with high performance
Journal of Materials Science: Materials in Electronics, 2020
Several off-stoichiometric compositions Bi 0.5 Sb 1.5+x Te 3+δ (x = 0.2; δ = 0, 0.12, 0.14) were deliberately synthesized to produce in-situ composites based on compositional engineering approach. The structural characterization of these materials employing XRD, SEM, and HR-TEM reveals the formation of in-situ-composites containing Bi 0.5 Sb 1.5 Te 3 as matrix phase and minor phases of either Sb rich or Te rich in different compositions. Thermoelectric properties of these Bi 0.5 Sb 1.5+x Te 3+δ (x = 0.2; δ = 0, 0.12, 0.14) composites were studied in a wide range of temperatures extending from room temperature to 500 K. The electronic transport of these composites exhibits p-type semiconducting materials. The lowest thermal conductivity of ~ 0.69 W/m K @310 K was observed for Bi 0.5 Sb 1.7 Te 3.12 composite, which was noted to be 14% reduced thermal conductivity when compared with that of the state-of-the-art Bi 0.5 Sb 1.5 Te 3 (κ = 0.82 W/m K) material. In addition to this, an enhanced power factor was also observed in Bi 0.5 Sb 1.7 Te 3.12 which is primarily due to increased electrical conductivity of these materials. This enhanced power factor of the composition of Bi 0.5 Sb 1.7 Te 3.12 coupled with reduced thermal conductivity yields to high ZT ~ 1.13 at nearly room temperature, making these materials viable for large scale applications.
RSC Advances, 2018
Bi 0.88Àx Zn x Sb 0.12 alloys with x ¼ 0.00, 0.05, 0.10, and 0.15 were prepared using hydrothermal synthesis in combination with evacuating-and-encapsulating sintering. The effects of partial Zn substitution for Bi and different sintering temperatures on the thermoelectric properties of Bi 0.88Àx Zn x Sb 0.12 alloys were investigated between 25 K and 425 K. Both the electrical conductivity and absolute thermopower are enhanced for the set of alloys sintered at 250 C. The maximum power factor of 57.60 mW cm À1 K À2 is attained for the x ¼ 0.05 alloy sintered at 250 C. As compared with Zn-free Bi 0.88 Sb 0.12 , both the total thermal conductivity and lattice component are reduced upon Zn doping. Bipolar conduction is observed in both electronic and thermal transport. The maximum zT of 0.47 is attained at 275 K for the x ¼ 0.05 alloy sintered at 250 C.