- Effect of Hydrogen Reduction Treatment on Room-Temperature Thermoelectric Performance of p-type Thermoelectric Powders
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Kyung-Tae Kim, Kyeong-Mi Jang, Gook-Hyun Ha
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J Korean Powder Metall Inst. 2010;17(2):136-141.
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DOI: https://doi.org/10.4150/KPMI.2010.17.2.136
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- Bismuth-telluride based (Bi_0.2Sb_0.8)_2Te_3 thermoelectric powders were fabricated by two-step planetary milling process which produces bimodal size distribution ranging 400;nm;sim;2;µm. The powders were reduced in hydrogen atmosphere to minimize oxygen contents which cause degradation of thermoelectric performance by decreasing electrical conductivity. Oxygen contents were decreased from 0.48% to 0.25% by the reduction process. In this study, both the as-synthesized and the reduced powders were consolidated by the spark plasma sintering process at 350°C for 10 min at the heating rate of 100°C/min and then their thermoelectric properties were investigated. The sintered samples using the reduced p-type thermoelectric powders show 15% lower specific electrical resistivity (0.8;mOmegacdotcm) than those of the as-synthesized powders while Seebeck coefficient and thermal conductivity do not change a lot. The results confirmed that ZT value of thermoelectric performance at room temperature was improved by 15% due to high electric conductivity caused by the controlled oxygen contents present at bismuth telluride materials.
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Citations
Citations to this article as recorded by  - Influence of Metal-Coating Layer on an Electrical Resistivity of Thick-Film-Type Thermoelectric Modules Fabricated by a Screen Printing Process
Kyung-Tae Kim, Hye-Young Koo, Gook-Hyun Ha
Journal of Korean Powder Metallurgy Institute.2011; 18(5): 423. CrossRef
- Fabrication and Thermoelectric Properties of Carbon Nanotube/Bi2Te3 Composites
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Kyung-Tae Kim, Kyeong-Mi Jang, Kyong-Ju Kim, Gook-Hyun Ha
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J Korean Powder Metall Inst. 2010;17(2):107-112.
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DOI: https://doi.org/10.4150/KPMI.2010.17.2.107
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Abstract
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- Carbon-nanotube-embedded bismuth telluride (CNT/Bi_2Te_3) matrix composites were fabricated by a powder metallurgy process. Composite powders, whereby 5 vol.% of functionalized CNTs were homogeneously mixed with Bi_2Te_3 alloying powders, were successfully synthesized by using high-energy ball milling process. The powders were consolidated into bulk CNT/Bi_2Te_3 composites by spark plasma sintering process at 350°C for 10 min. The fabricated composites showed the uniform mixing and homogeneous dispersion of CNTs in the Bi_2Te_3 matrix. Seebeck coefficient of CNT/Bi_2Te_3 composites reveals that the composite has n-type semiconducting characteristics with values ranging -55;µV/K to -95;µV/K with increasing temperature. Furthermore, the significant reduction in thermal conductivity has been clearly observed in the composites. The results showed that CNT addition to thermoelectric materials could be useful method to obtain high thermoelectric performance.
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