• Proceedings of the Materials Research Society of Korea Conference
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• 1994.05a
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• pp.46-47
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• 1994

• Korean Journal of Materials Research
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• v.10 no.3
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• pp.246-252
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• 2000

Thermoelectric properties of the $Bi_2(Te_{0.85}Se_{0.15})_3$ alloy, prepared by mechanical alloying and hot pressing, were investigated with the variation of the hot-pressing temperature ranging from $300^{\circ}C$ to $550^{\circ}C$. Contrary to the p-type behavior of single crystal, the hot-pressed $Bi_2(Te_{0.85}Se_{0.15})_3$ alloy exhibited n-type conduction without addition of donor dopant. When the $Bi_2(Te_{0.85}Se_{0.15})_3$ powders were annealed in $(50{\%}\;H_2+50{\%}\;Ar)$ atmosphere, the hot-pressed specimens exhibited a positive Seebeck coefficient due to the reduction of the electron concentration by removal of the oxide layer on the powder surface and annealing-out of the excess Te vacancies. Figure-of-merit of the hot-pressed $Bi_2(Te_{0.85}Se_{0.15})_3$ alloy was improved by hot pressing at temperatures above $450^{\circ}C$, and the maximum value of $1.92{\times}10^{-3}/K$ was obtained for the specimen hot-pressed at $550^{\circ}C$.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.4 no.4
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• pp.363-369
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• 1994

Bimuth telluride base thermoelectrics are prepared by AC current applied hot pressing method. It is possible to minimize the defects arising from the vaporization of Te, thanks to the very short processing time compared to the single crystal growing method. The optimum conditions for the AC applied hot pressing of 95 mol% $Bi_2Te_3-5 mol% Bi_2Se_3$ thermoelectrics are sintering at $400^{\circ}C$, for 2 minutes, under 1500 kgf/$\textrm{cm}^2$, with the particle size of $125 to 250 {\mu}m$, range of powder. The resultant Z value (figure of merit) was $2.2{\times}10^{-3}/K$.

• Journal of the Korean Vacuum Society
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• v.3 no.3
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• pp.309-315
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• 1994

순간증착법으로 p형(Bi0.5Sb1.5Te3)과 n형(Bi2Te24Se0.6)열전박막을 제조하여 상온에서 Seebeck 계 수, 전기전도도 및 열전성능지수를 측정하였다. 또한 금속재 mask를 이용하여 다중접점 박막형 열전소 자를 제작하고 그 작동특성을 조사하였다. 이때 소자의 고온부와 저온부의 온도를 직접측정하기 위하여 copper/constantan 박막을 접점부에 증착하여 열전쌍이 되게 하였다. p/n 접점이 5쌍이 소자의 경우 Peltier 효과에 의해 생성된 최대온도차는 22K이었다.

• Proceedings of the Korean Vacuum Society Conference
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• 1993.07a
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• pp.93-94
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• 1993

• Journal of Powder Materials
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• v.5 no.1
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• pp.50-56
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• 1998

A new process using rapid solidification (melt spinning method) followed by pressing and sintering was investigated to produce the n-type thermoelectric ribbons of 90% $Bi_2Te_3$+10% $Bi_2Se_3$ doped with $CdCl_2$. Quenched ribbons are very brittle and consisted of homogeneous $Bi_2Te_3-Bi_2Se_3$ pseudo-binary solid solutions. Property variations of the materials was investigated as a function of variables, such as dopant $CdCl_2$ quantity and sintering temperature. When the process parameters were optimized, the maximum figure of merit was $2.146{\times}10^{-3}K^{-1}$.

• Journal of Powder Materials
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• v.22 no.4
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• pp.254-259
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• 2015

$Bi_2Te_3$ related compounds show the best thermoelectric properties at room temperature. However, n-type $Bi_2Te_{2.7}Se_{0.3}$ showed no improvement on ZT values. To improve the thermolectric propterties of n-type $Bi_2Te_{2.7}Se_{0.3}$, this research has Cu-doped n-type powder. This study focused on effects of Cu-doping method on the thermoelectric properties of n-type materials, and evaluated the comparison between the Cu chemical and mechanical doping. The synthesized powder was manufactured by the spark plasma sintering(SPS). The thermoelectric properties of the sintered body were evaluated by measuring their Seebeck coefficient, electrical resistivity, thermal conductivity, and hall coefficient. An introduction of a small amount of Cu reduced the thermal conductivity and improved the electrical properties with Seebeck coefficient. The authors provided the optimal concentration of $Cu_{0.1}Bi_{1.99}Se_{0.3}Te_{2.7}$. A figure of merit (ZT) value of 1.22 was obtained for $Cu_{0.1}Bi_{1.9}Se_{0.3}Te_{2.7}$ at 373K by Cu chemical doping, which was obviously higher than those of $Cu_{0.1}Bi_{1.9}Se_{0.3}Te_{2.7}$ at 373K by Cu mechanical doping (ZT=0.56) and Cu-free $Bi_2Se_{0.3}Te_{2.7}$ (ZT=0.51).

• Nuclear Engineering and Technology
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• v.55 no.8
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• pp.3080-3087
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• 2023

Thermoelectric (TE) materials working in radioisotope thermoelectric generators are irradiated by neutrons throughout its service; thus, investigating the neutron irradiation stability of TE devices is necessary. Herein, the influence of neutron irradiation with fluences of 4.56 × 10¹⁰ and 1 × 10¹³ n/cm² by pulsed neutron reactor on the electrical and thermal transport properties of n-type Bi₂Te_2.7Se_0.3 and p-type Bi_0.5Sb_1.5Te₃ thermoelectric alloys prepared by cold-pressing and molding is investigated. After neutron irradiation, the properties of thermoelectric materials fluctuate, which is related to the material type and irradiation fluence. Different from p-type thermoelectric materials, neutron irradiation has a positive effect on n-type Bi₂Te_2.7Se_0.3 materials. This result might be due to the increase of carrier mobility and the optimization of electrical conductivity. Afterward, the effects of p-type and n-type TE devices with different treatments on the output performance of TE devices are further discussed. The positive and negative effects caused by irradiation can cancel each other to a certain extent. For TE devices paired with p-type Bi_0.5Sb_1.5Te₃ and n-type Bi₂Te_2.7Se_0.3 thermoelectric legs, the generated power and conversion efficiency are stable after neutron irradiation.

• Proceedings of the Materials Research Society of Korea Conference
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• 1994.05a
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• pp.44-45
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• 1994

• Journal of the Microelectronics and Packaging Society
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• v.18 no.4
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• pp.55-61
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• 2011

The n-type $Bi_2(Te_{0.9}Se_{0.1})_3$ powers were fabricated by mechanical alloying, mixed with tungsten(W) powders, and hot-pressed at $550^{\circ}C$ for 30 minutes. Thermoelectric properties of the hot-pressed $Bi_2(Te_{0.9}Se_{0.1})_3$ were characterized as a function of the volume percent of tungsten-powder addition. The power factor of the hot-pressed $Bi_2(Te_{0.9}Se_{0.1})_3$ was $21.9{\times}10^{-4}$ $W/m-K^2$, and was improved to $30.5{\times}10^{-4}$ $W/m-K^2$ by dispersion of 1 vol% W powders. While the dimensionless figure-of-merit of the $Bi_2(Te_{0.9}Se_{0.1})_3$ hot-pressed without dispersion of W powders was measured as 0.52 at room temperature, it became substantially enhanced to 0.95 with addition of 1 vol% W powders.