• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 추계학술대회 논문집
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• pp.83-84
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• 2007

Sn-filled and Ni-doped $CoSb_3$ skutterudites were prepared by encapsulated induction melting, and their filling and doping effects on thermoelectric properties were investigated. Single phase ${\delta}-CoSb_3$ was successfully obtained by encapsulated induction melting and subsequent heat treatment at 823K for 5 days. Nickel atoms acted as electron donors by substituting cobalt atoms. Thermoelectric properties were remarkably improved by Sn filling and Ni doping.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
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• pp.138-139
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• 2006

Metal organic chemical vapor deposition has been investigated for growth of $Sb_{2-x}Bi_xTe_3$ films on (001) GaAs substrates using diisopropyltelluride, triethylantimony and trimethylbismuth as metal organic sources. The thermoelectric properties were measured at room temperature and include Seebeck coefficient, electrical conductivity and Hall effect. In-plane carrier concentration and electrical Hall mobility were highly dependent on precursor's composition ratio and deposition temperature. The thermoelectric Power factor($={\alpha}^2{\sigma}$) was calculated from theses properties. The best Power factor was $2.6\;{\times}\;10^{-3}W/mK^2$, given by grown $Sb_{1.6}Bi_{0.4}Te_3$ at $450^{\circ}C$. These materials could potentially be incorporated into advanced thermoelectric unicouples for a variety of power generation applications.

• 한국재료학회지
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• 제15권10호
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• pp.667-670
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• 2005

Binary skutterudite $CoSb_3$ compounds were prepared by the arc melting and hot pressing processes and their thermoelectric properties were investigated in the range from 300 to 600 K. Annealing effect was correlated to phase transformation and homogenization. Thermoelectric properties of the arc-melted and hot-pressed $CoSb_3$ were discussed and compared. Undoped intrinsic $CoSb_3$ prepared by the arc melting showed p-type conduction, while it showed metallic behavior with increasing measuring temperature. However, hot pressed specimens showed n-type conduction, possibly due to Sb evaporation. Thermoelectric properties were remarkably improved by annealing In vacuum and they were closely related to phase transformation.

• 폴리머
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• 제37권5호
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• pp.638-641
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• 2013

유연 열전소자를 제조하기 위한 열전재료로서, graphite nanosheet(GNS)와 poly(vinylidene fluoride) (PVDF)를 복합화하여 GNS/PVDF 복합체를 제조하였다. GNS의 함량에 따른 전기전도도, 열전도도, 지벡상수를 측정하여 열전성능을 확인하였다. GNS의 함량이 10에서 70 wt%로 증가하면서 전기전도도는 389에서 1512 S/m로 향상되는 결과를 보였다. 복합체의 전기전도도가 크게 증가하는 반면에 지벡 상수는 26.7에서 31.2 ${\mu}V/K$로 큰 변화를 보이지 않았으며, 열전도도 역시 0.24 W/m K를 유지하면서 변화를 보이지 않았다. 고분자와의 복합화를 통하여 GNS 자체의 높은 열전도도를 낮춤으로써 향상된 열전성능을 갖는 열전재료를 제조할 수 있었다.

• 한국재료학회지
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• 제32권3호
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• pp.132-138
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• 2022

Zintl phase Mg₃Sb₂ is a promising thermoelectric material in medium to high temperature range due to its low band gap energy and characteristic electron-crystal phonon-glass behavior. P-type Mg₃Sb₂ has conventionally exhibited lower thermoelectric properties compared to its n-type counterparts, which have poor electrical conductivity. To address these problems, a small amount of Sn doping was considered in this alloy system. P-type Mg₃Sb₂ was synthesized by controlled melting, pulverizing, and subsequent vacuum hot pressing (VHP) method. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to investigate phases and microstructure development during the process. Single phase Mg₃Sb₂ was successfully formed when 16 at.% of Mg was excessively added to the system. Nominal compositions of Mg_3.8Sb_2-xSn_x (0 ≤ x ≤ 0.008) were considered in this study. Thermoelectric properties were evaluated in terms of Seebeck coefficient, electrical conductivity, and thermal conductivity. A peak ZT value ≈ 0.32 was found for the specimen Mg_3.8Sb_1.994Sn_0.006 at 873 K, showing an improved ZT value compared to intrinsic one. Transport properties were also evaluated and discussed.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.304.2-304.2
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• 2014

Chalcogenides (Te,Se) and pnictogens(Bi,Sb) materials have been widely investigated as thermoelectric materials. Especially, Bi2Te3 (Bismuth telluride) compound thermoelectric materials in thin film and nanowires are known to have the highest thermoelectric figure of merit ZT at room temperature. Currently, the thermoelectric material research is mostly driven in two directions: (1) enhancing the Seebeck coefficient, electrical conductivity using quantum confinement effects and (2) decreasing thermal conductivity using phonon scattering effect. Herein we demonstrated influence of annealing temperature on structural and thermoelectrical properties of Bismuth-telluride-selenide ternary compound thin film. Te-rich Bismuth-telluride-selenide ternary compound thin film prepared co-deposited by thermal evaporation techniques. After annealing treatment, co-deposited thin film was transformed amorphous phase to Bi2Te3-Bi2Te2Se1 polycrystalline thin film. In the experiment, to investigate the structural and thermoelectric characteristics of Bi2Te3-i2Te2Se1 films, we measured Rutherford Backscattering spectrometry (RBS), X-ray diffraction (XRD), Raman spectroscopy, Scanning eletron microscopy (SEM), Transmission electron microscopy (TEM), Seebeck coefficient measurement and Hall measurement. After annealing treatment, electrical conductivity and Seebeck coefficient was increased by defect states dominated by selenium vacant sites. These charged selenium vacancies behave as electron donors, resulting in carrier concentration was increased. Moreover, Thermal conductivity was significantly decreased because phonon scattering was enhanced through the grain boundary in Bi2Te3-Bi2Te2Se1 polycrystalline compound. As a result, The enhancement of thermoelectric figure-of-merit could be obtained by optimal annealing treatment.

• 마이크로전자및패키징학회지
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• 제26권4호
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• pp.149-156
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• 2019

5쌍의 Bi₂Te₃계 p-n 가압소결체 열전레그들로 구성되어 있으며 상하부 기판이 없고 내부는 polydimethylsiloxane (PDMS)로 충진되어 있는 신축열전모듈을 형성하고, 이의 신축특성과 발전특성을 분석하였다. 신축열전모듈에 변형률 0~0.1 범위의 신축변형 싸이클을 10회 인가하여도 모듈의 integrity가 잘 유지되었으며, 인장변형률이 0.2로 증가시 Cu 전극과 열전레그 사이의 접합부 파단에 의해 모듈이 open 되었다. 신축열전모듈은 열전레그 양단간의 온도차가 2.2 K일 때 4.6 mV의 open circuit 전압을 나타내었으며, 변형률 0~0.1 범위의 인장변형에 의한 open circuit 전압의 변화는 5% 미만이었다. 신축열전모듈은 0.1의 변형률로 인장된 상태에서 레그 양단간 온도차 2.2 K에 의해 18.5 ㎼의 최대발전출력을 나타내었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.425-425
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• 2008

Bismuth-antimony-telluride based thermoelectric thin film materials were prepared by metal organic vapor phase deposition using trimethylbismuth, triethylantimony and diisopropyltelluride as metal organic sources. A planar type thermoelectric device has been fabricated using p-type $Bi_{0.4}Sb_{1.6}Te_3$ and n-type $Bi_2Te_3$ thin films. Firstly, the p-type thermoelectric element was patterned after growth of $4{\mu}m$ thickness of $Bi_{0.4}Sb_{1.6}Te_3$ layer. Again n-type $Bi_2Te_3$ film was grown onto the patterned p-type thermoelectric film and n-type strips are formed by using selective chemical etchant for $Bi_2Te_3$. The top electrical connector was formed by thermally deposited metal film. The generator consists of 20 pairs of p- and n-type legs. We demonstrate complex structures of different conduction types of thermoelectric element on same substrate by two separate runs of MOCVD with etch-stop layer and selective etchant for n-type thermoelectric material. Device performance was evaluated on a number of thermoelectric devices. To demonstrate power generation, one side of the device was heated by heating block and the voltage output was measured. The highest estimated power of 1.3mW is obtained at the temperature difference of 45K. We provide a promising approach for fabricating thin film thermoelectric generators by using MOCVD grown thermoelectric materials which can employ nanostructures for high thermoelectric properties.

• 한국재료학회지
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• 제18권4호
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• pp.175-180
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• 2008

In this study, the thermoelectric power and resistivity of the perovskite manganite $La_{0.75}Ba_{0.25}MnO_3$ were investigated in the temperature range 300K-1200K. The electrical resistivity and thermoelectric power indicate a transport mechanism dominated by adiabatic small-polaron hopping. The power factor increases from $2{\times}10^{-6}W/mK^2$ to $1{\times}10^{-5}W/mK^2$ as to the temperature increases from 400K to 1200K, which indicates that the compound is highly feasible as a thermoelectric material at high temperatures.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2008년도 춘계학술대회 논문집
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• pp.525-527
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• 2008

N-Type $SbI_3$-doped $95%{Bi_2}{Te_3}-5%{Bi_2}{Se_3}$ compounds were prepared by a gas atomization and Magnetic Pulsed Compaction process. The dynamic recrystallization and thermoelectric properties of the MPCed bulks with consolidation temperatures and times were investigated by a combination of microscopy, XRD and thermoelectric property testing. The microstructure of MPCed bulk shows homogeneous and fine distribution through consolidated bulks due to dynamic recrystallization during hot MPC. This research presented the challenges toward the successful consolidation of thermoelectric powder using magnetic pulsed compaction (MPC).