• 한국재료학회지
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• 제8권3호
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• pp.245-251
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• 1998

Bi를 첨가한 n형 PbTe 가압소결체를 기계적 합금화 공정으로 제조하여, 소결 특성과 열전특성을 분석하고 이를 용해/분쇄법으로 제조한 PbTe가압소결체와 비교하였다. 기계적 합금화 공정으로 제조한 PbTe가압소결체에는 용해/분쇄법으로 제조한 시편에 비해 Seebeck계수가 음의 값으로 증가하였으며, 전기비저항이 증가하고 열전도도가 감소하였다. 또한 기계적 합금화 공정으로 제조한 PbTe에서 최대성능지수가 증가하였으며, \ulcorner대성능지수를 나타내는 온도가 저온으로 이동하였다. 0.3wt% Bi를 첨가한 PbTe를 $650^{\circ}C$에서 가압소결시 기계적 합금화 공정으로 제조한 시편은 $200^{\circ}C$에서 $1.33\times10^{-3}/K$의 최대성능지수를 나타내었으며, 용해/분쇄법으로 제조한 시편은 $400^{\circ}C$에서 $1.07\times10^{-3}/K$의 최대성능지수를 나타내었다.

• 혜화의학회지
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• 제15권1호
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• pp.33-40
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• 2006

Objectives : This study is aimed to investigate acupuncture treatments for blurred vision, tinnitus, difficulty in urination and bi-syndrome caused by aging process through oriental medical documents. methods : We researched 21 oriental medical classics for the acupuncture treatments of blurred vision, tinnitus, difficulty in urination and bi-syndrome caused by aging or deficiency. Results & conclusions : 1. Disharmony between yin and yang, disharmony between organs, disharmony of essence, qi, spirit, blood and body fluid are the main features of aging. 2. ST36, BL18, BL10, CV24, ST1, BL23 have been most frequently used for acupuncture to treat blurred vision caused by aging. For moxibustion, ST36 has been most frequently used. 3. GB2, TE21, TE17, SI19, TE3 are the mainly used points for acupuncture to treat tinnitus and deafness caused by aging. For moxibustion, LI1 and BL15 have been most frequently used. 4. CV3, CV7, CV4, BL67, LR8, LR4 have been most frequently used to treat difficulty in urination caused by aging. 5. LI11, GB34, GB30, LI4, ST36, TE10, TE5, Sama (extra point) have been most frequently used to treat numbness, paralysis and bi syndrome caused by aging.

• 한국분말재료학회지
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• 제24권2호
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• pp.141-146
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• 2017

$Bi_2Te_3$ powders are recovered by wet chemical reduction for waste n-type thermoelectric chips, and the recovered particles with different morphologies are prepared using various surfactants such as cetyltrimethylammonium bromide (CTAB), sodium dodecylbenzenesulfonate (SDBS), and ethylenediaminetetraacetic acid (EDTA). When citric acid is added as the surfactant, the shape of the aggregated particles shows no distinctive features. On the other hand, rod-shaped particles are formed in the sample with CTAB, and sheet-like particles are synthesized with the addition of SDBS. Further, particles with a tripod shape are observed when EDTA is added as the surfactant. The growth mechanism of the particle shapes depending on the surfactant is investigated, with a focus on the nucleation and growth phenomena. These results help to elucidate the intrinsic formation mechanism of the rod, plate, and tripod structures of the $Bi_2Te_3$ recovered by the wet reduction process.

• 한국재료학회지
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• 제15권1호
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• pp.14-18
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• 2005

Ni-Cr-Sn-Bi alloys were prepared by air melting and sand casting method and their anti-galling behaviors were examined. Anti-galling properties were dominantly influenced by Bi-rich low temperature precipitates. Alloying effects on the anti-galling properties were investigated for several alloying elements to improve anti-galling properties of the alloy. An alloy with $1-3wt\%$ of Te showed markedly improved anti-galling properties. Metallographic and tribological tests were carried out to find out reasons for excellent properties. It was found that Te containing alloy has finely distributed precipitates of Bi-rich phase. The addition of Te changed the morphology of the Ni-rich primary phase from globular to fine dendritic. As a result, the anti-galling phase precipitated between dendrite arms with fine distribution showed excellent anti-galling properties.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2018년도 춘계학술대회 논문집
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• pp.81-81
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• 2018

Bi-Te계 열전소자는 상온에서의 열전 효율이 우수하기 때문에 항공, 컴퓨터 등의 열전발전 또는 열전냉각 모듈에 널리 사용된다. 이 열전소자를 활용한 열전모듈은 다수의 n형 및 p형 열전소자가 세라믹 위에 형성된 Cu 전극에 전기적으로 직렬이 되도록 서로 솔더링 접합이 되어 있는 구조를 가지고 있다. 이처럼 직렬 연결된 방식에서는 높은 접합강도를 필요로 한다. 열전모듈 제작 시 Bi-Te 계 소자를 바로 Cu 기판에 접합시키면 솔더에 들어있는 Sn과 기판의 Cu가 접합하는 과정에서 소재 내로 확산하여 접합강도를 저하시킨다. 이러한 열전모듈의 접합강도 저하를 막기 위해 무전해 Ni-W-P 도금층을 확산 방지층으로 적용하였다. 본 연구에서는 Ni-W-P 도금이 Bi-Te 계 열전 모듈의 접합강도에 미치는 영향을 조사하였다. 본 연구에서는 Bi-Te계 열전소자에 양호한 밀착성을 가지는 Ni-W-P 도금층을 형성시키기 위해서 알루미나 분말을 이용한 sand-blasting 방법을 사용하여 Bi-Te 소재 표면에 분사하는 방법으로 표면을 거칠게 하였다. 그 후 무전해 Ni-W-P 도금을 $85^{\circ}C$에서 20분간 실시하여 약 4um의 Ni-W-P 도금층을 형성시켰다. 열전 모듈은 Sn-Ag-Cu 솔더를 사용하여 제작하였으며 접합강도는 Bonding tester를 사용하여 측정하였다. 제작한 열전 모듈의 단면 및 파단면 관찰을 통하여 접합강도가 변하는 요인을 조사하였다. 제작한 열전 모듈의 단면을 FE-EPMA로 관찰한 결과 Ni-W-P 도금층이 Bi-Te 소자와 Sn과 Cu사이의 확산을 방지하는 확산방지층 역할을 하는 것을 관찰할 수 있었다. 또한 열처리 전 열전모듈과 200도, 150시간 열처리 후 접합강도를 각각 측정해 본 결과, 열처리 후의 접합강도가 상승하는 것을 확인 할 수 있었다. 따라서 Bi-Te계 열전모듈 제작에 무전해 Ni-W-P 도금층을 형성시키므로 인해 확산방지층의 생성과 접합강도의 상승에 도움을 주었다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2013년도 춘계학술대회 논문집
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• pp.833-834
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• 2013

• 한국분말재료학회지
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• 제23권2호
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• pp.120-125
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• 2016

P-type ternary $Bi_{0.5}Sb_{1.5}Te_3$ alloys are fabricated via mechanical alloying (MA) and spark plasma sintering (SPS). Different ball sizes are used in the MA process, and their effect on the microstructure; hardness, and thermoelectric properties of the p-type BiSbTe alloys are investigated. The phases of milled powders and bulks are identified using an X-ray diffraction technique. The morphology of milled powders and fracture surface of compacted samples are examined using scanning electron microscopy. The morphology, phase, and grain structures of the samples are not altered by the use of different ball sizes in the MA process. Measurements of the thermoelectric (TE) transport properties including the electrical conductivity, Seebeck coefficient, and power factor are measured at temperatures of 300-400 K for samples treated by SPS. The TE properties do not depend on the ball size used in the MA process.

• Journal of Magnetics
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• 제10권4호
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• pp.149-151
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• 2005

The electric properties of a single crystal bismuth telluride doped with a small concentration of Erbium, $Bi_{z-x}Er_xTe_3$ with x = 0.002, are investigated as a function of temperature. The resistivity was obtained by using the van der Pauw method. The measured electrical resistivity is 78 ${\mu}{\Omega}cm$ at 4.2 K. The charge density of $Bi_{z-x}Er_xTe_3$ is found to be $2{\times}10^{19}/cm^3$ at 4.2 K. It turns out that $Bi_{z-x}Er_xTe_3$ is a p-type semiconductor. It is discussed that the high mobility and less density support that $Bi_{z-x}Er_xTe_3$ is a potential sensor with high energy resolution. Comparison with an established material (i.e. Au:Er alloy) is also discussed.

• E2M - 전기 전자와 첨단 소재
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• 제9권1호
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• pp.67-75
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• 1996

This paper has presented the characteristics of thermoelectric devices and the plots of thermoelectric cooling and heating as a function of currents for different temperatures. The maximum cooling and heating(.DELTA.T) for (BiSb)$\_$2/Te$\_$3/ and Bi$\_$2/(TeSe)$\_$3/ as a function of currents is about 75.deg. C, A solderable ceramic insulated thermoelectric module. Each module contains 31 thermoelectric devices. Thermoelectric material is a quaternary alloy of bismuth, tellurium, selenium, and antimony with small amounts of suitable dopants, carefully processed to produce an oriented polycrystalline ingot with superior anisotropic thermoelectric properties. Metallized ceramic plates afford maximum electrical insulation and thermal conduction. Operating temperature range is from -156.deg. C to +104.deg. C. The amount of Peltier cooling is directly proportional to the current through the sample, and the temperature gradient at the thermoelectric materials junctions will depend on the system geometry.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.459-460
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• 2006

N-type $Bi_2Te_3-Sb_2Te_3$ solid solutions doped with 1$CdCl_2$ was prepared by melt spinning, crushing and vacuum sintering processes. Microstructure, bending strength and thermoelectric property were investigated as a function of the doping quantity from 0.03wt.% to 0.10wt.% and sintering temperature from $400^{\circ}C$ to $500^{\circ}C$, and finally compared with those of conventionally fabricated alloys. The alloy showed a good structural homogeneity as well as bending strength of $3.88Kgf/mm^2$. The highest thermoelectric figure of merit was obtained by doping 0.03wt.% and sintering at $500^{\circ}C$.