Journal of Powder Materials

Kyung-Tae Kim

4 Articles

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; J Korean Powder Metall Inst. 2011;18(5):423-429.; DOI: https://doi.org/10.4150/KPMI.2011.18.5.423

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Thermoelectric-thick films were fabricated by using a screen printing process of n and p-type bismuth-telluride-based pastes. The screen-printed thick films have approximately 30 µm in thickness and show rough surfaces yielding an empty gap between an electrode and the thick film. The gap might result in an increase of an electrical resistivity of the fabricated thick-film-type thermoelectric module. In this study, we suggest a conductive metal coating onto the surfaces of the screen-printed paste in order to reduce the contact resistance in the module. As a result, the electrical resistivity of the thermoelectric module having a gold coating layer was significantly reduced up to 30% compared to that of a module without any metal coating. This result indicates that an introduction of conductive metal layers is effective to decrease the contact resistivity of a thick-film-typed thermoelectric module processed by screen printing.

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Flexible Thermoelectric Device Using Thick Films for Energy Harvesting from the Human Body
Han Ki Cho, Da Hye Kim, Hye Sun Sin, Churl-Hee Cho, Seungwoo Han
Journal of the Korean Ceramic Society.2017; 54(6): 518. CrossRef

Synthesis of Bi-Sb-Te-based Thermoelectric Powder by an Oxide-reduction Process: Gil-Geun Lee, Sung-Hyun Kim, Gook-Hyun Ha, Kyung-Tae Kim; J Korean Powder Metall Inst. 2010;17(4):336-341.; DOI: https://doi.org/10.4150/KPMI.2010.17.4.336

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The present study focused on the synthesis of Bi-Sb-Te-based thermoelectric powder by an oxidereduction process. The phase structure, particle size of the synthesized powders were analyzed using XRD and SEM. The synthesized powder was sintered by the spark plasma sintering method. The thermoelectric property of the sintered body was evaluated by measuring the Seebeck coefficient and specific electric resistivity. The Bi_0.5Sb_1.5Te_3 powder had been synthesized by a combination of mechanical milling, calcination and reduction processes using mixture of Bi_2O_3, Sb_2O_3 and TeO_2 powders. The sintered body of the Bi_0.5Sb_1.5Te_3 powder synthesized by an oxide-reduction process showed p-type thermoelectric characteristics, even though it had lower thermoelectric properties than the sintered body of the Bi_0.5Sb_1.5Te_3 thermoelectric powder synthesized by the conventional melting-crushing method.

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Synthesis of N-type Bi2Te2.7Se0.3 Compounds through Oxide-Reduction Process and Related Thermoelectric Transport Properties
Young Soo Lim, Bae Gun Park, Gil-Geun Lee
Korean Journal of Metals and Materials.2022; 60(6): 463. CrossRef
The Electric and Thermal Properties of Spark Plasma Sintered Bi0.5Sb1.5Te3
Gil-Geun Lee, Young-Hoon Choi, Gook-Hyun Ha
Journal of Korean Powder Metallurgy Institute.2012; 19(4): 285. CrossRef
Synthesis and Characterization of (AgSbTe2)15(GeTe)85Thermoelectric Powder by Gas Atomization Process
Hyo-Seob Kim, Jin-Kyu Lee, Jar-Myung Koo, Byong-Sun Chun, Soon-Jik Hong
Journal of Korean Powder Metallurgy Institute.2011; 18(5): 449. CrossRef
Thermoelectric Properties of Bi2Te2.7Se0.3Powder Synthesized by an Oxide-Reduction Process
Bae-Gun Park, Gil-Geun Lee, Woo-Yeol Kim, Gook-Hyun Ha
Journal of Korean Powder Metallurgy Institute.2011; 18(5): 437. CrossRef

Effect of Hydrogen Reduction Treatment on Room-Temperature Thermoelectric Performance of p-type Thermoelectric Powders: Kyung-Tae Kim, Kyeong-Mi Jang, Gook-Hyun Ha; J Korean Powder Metall Inst. 2010;17(2):136-141.; 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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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: Kyung-Tae Kim, Kyeong-Mi Jang, Kyong-Ju Kim, Gook-Hyun Ha; J Korean Powder Metall Inst. 2010;17(2):107-112.; DOI: https://doi.org/10.4150/KPMI.2010.17.2.107

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Abstract PDF: 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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