• Title/Summary/Keyword: TE5

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Synthesis of Bi-Sb-Te-based Thermoelectric Powder by an Oxide-reduction Process (산화물 환원공정에 의한 Bi-Sb-Te계 열전분말 합성)

  • Lee, Gil-Geun;Kim, Sung-Hyun;Ha, Gook-Hyun;Kim, Kyung-Tae
    • Journal of Powder Materials
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    • v.17 no.4
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    • pp.336-341
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    • 2010
  • 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 $Bi_{0.5}Sb_{1.5}Te_3$ 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 $Bi_{0.5}Sb_{1.5}Te_3$ 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 $Bi_{0.5}Sb_{1.5}Te_3$ thermoelectric powder synthesized by the conventional melting-crushing method.

A Study on the Diffusion Barrier at the p/n Junctions of $Bi_{0.5}Sb_{1.5}Te_3/Bi_2Te_{2.4}Se_{0.6} p/n$ Thermoelectric Thin Films (열전 박막 $Bi_{0.5}Sb_{1.5}Te_3/Bi_2Te_{2.4}Se_{0.6} p/n$ 접합에서의 확산 장벽에 관한 연구)

  • Kim, Il-Ho;Lee, Dong-Hui
    • Korean Journal of Materials Research
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    • v.6 no.7
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    • pp.678-683
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    • 1996
  • In the fabrication processes of thin film thermoelectrics, a subsequent annealing treatment is inevitable to reduce the defects and residual stresses introduced during the film growth, and to make the uniform carrier concentration of the film. However, the diffusion-induced atomic redistribution and the broadening of p/n junction region are expected to affect the thermoelectric properties of thin film modules. The present study intends to investigate the diffusion at the p/n junctions of thermoelectric thin films and to relate it to the property changes. The film junctions of p-type(Bi0.5Sb1.5Te3)and n-type(Bi2Te2.4Se0.6)were prepared by the flash evaporation method. Aluminum thin layer was employed as a diffusion barrier between p-and n-type films of the junction. This was found to be an effective barrier by showing a negligible diffusion into both type films. After annealing treatment, the thermoelectric properties of p/n couples with aluminum barrier layer were accordingly retained their properties without any deterioration.

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Extensive investigations of photon interaction properties for ZnxTe100- x alloys

  • Singh, Harinder;Sharma, Jeewan;Singh, Tejbir
    • Nuclear Engineering and Technology
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    • v.50 no.8
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    • pp.1364-1371
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    • 2018
  • An extensive investigation of photon interaction properties has been made for $Zn_xTe_{100-x}$ alloys (where x = 5, 20, 30, 40, 50) to explore its possible use in sensing and shielding gamma radiations. The results show better and stable response of ZnTe alloys for various photon interaction properties over the wide energy range, with an additional benefit of ease in fabrication due to lower melting points of Zn and Te. Mass attenuation coefficient values show strong dependence on photon energy as well as composition. Effective atomic number has maximum value for $Zn_5Te_{95}$ and lowest for $Zn_{50}Te_{50}$ in the entire energy region. The alloy sample with maximum $Z_{eff}$ shows minimal value of $N_e$ and vice versa. Mean free path follows inverse trend as observed for mass attenuation coefficient. The exposure and energy absorption buildup factors depend upon photon energy, penetration thickness and composition (effective atomic number) of $Zn_xTe_{100-x}$ alloys. It finds its application for sensing and shielding from highly energetic and highly penetrating photons at sites where radioactive materials were used and visibility of material is not a big constraint. Further, energy down conversion property of ZnTe alloys with subsequent emission in green band suggests its potential use in sensing gamma photons.

CuPt-type ordering in Zn-rich $Cd_xZn_{1-x}$Te epilayers grown on GaAs and ZnTe/GaAs (GaAs, ZnTe/GaAs 기판위 성장된 고농도 Zn 조성의 $Cd_xZn_{1-x}$Te 에피층에서의 CuPt형 나노 규칙상 형성)

  • 권명석
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.13 no.5
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    • pp.230-234
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    • 2003
  • CuPt-type ordering has been observed in Zn-rich $Cd_xZn_{1-x}$Te epilayers grown on (001)GaAs and ZnTe/GaAs(001) substrates. X-ray diffraction, electron beam diffraction, high-resolution transmission electron microscopy and low-temperature photoluminescence have been used to characterize the CuPt-type ordering in Zn-rich $Cd_xZn_{1-x}$Te epilayers.

An evaluation on crystallization of amorphous (InTe)x(GeTe)y thin films by nano-pulse illumination (나노-펄스 노출에 따른 비정질(InTe)x(GeTe)y박막의 결정화 속도 평가)

  • Song, Ki-Ho;Seo, Jae-Hee;Lee, Hyun-Yong
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2008.11a
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    • pp.419-420
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    • 2008
  • In this work, we report several experimental data capable of evaluating the phase transition characteristics of (InTe)x(GeTe)y (x = 0.1, 0.3, y =1) pseudo-binary thin films. (InTe)x(GeTe)y phase change thin films have been prepared by thermal evaporator. The crystallization characteristics of amorphous (InTe)x(GeTe)y thin films were investigated by using nano-pulse scanner with 658 nm laser diode (power : 1~17 mW, pulse duration : 10~460 ns) and XRD measurement. It was found that the crystalline speed of In-Ge-Te thin films are faster than $Ge_2Sb_2Te_5$[1] and also the crystalline temperature is higher. Changes in the optical transmittance of as-deposited and annealed films were measured using a UV-VIS-IR spectrophotometer and four-point probe was used to measure the sheeresistance of InGeTe films annealed at different temperature.

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Polyoxyethylene Tocopheryl Ethers; A Series of Novel Surfactants from Tocopherol for Functional Cosmetics (토코페롤에서 유도된 기능성 화장품용의 새로운 계면 활성제)

  • 김영대;김창규
    • Journal of the Society of Cosmetic Scientists of Korea
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    • v.18 no.1
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    • pp.1-41
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    • 1992
  • A new and unique class of nonionic surfactants was synthesized by reacting biological a-tocopherol with ethylene oxide for functional cosmetics. The structures were confirmed by Hl-UMR, FT-lR, TLC and elemental analysis. POV and conjugated diene value study for EPO showed POE(n)TE had antioxidative effect similar to tocopheryl acetate Protective effect on cell membrane in photohemolysis of POE(5)TE, POE(10)TE and POE(18)TE were slightly lower than tocopherol but higher than nonoxynol-12, and POE(10)TE had UV absorption power comparable with tocopherol and homosalate. Biological activity of the hydrophobic group of the new surfactants make them unique and different from those of conventional nonionic surfactants Systematic safety evaluations of POE(n)TEs on the skin and eye proved that they are as safe as tocopherol. The results of physicochemical study showed POE(10)TE had the lowest CMC value, POE(18)TE had the maximum surface tension reduction and the highest foam volume and POE(n)TEs had various HLB values by the degree of ethoxylation. The test resul Is of technological and practical applications of these surfactants for cosmetics showed some POE(n)TEs were superior to conventional surfactants. POE(5)TE in W/O emulsions, POE(10)TE and POE(12)TE in O/W emulsions, POE(12)TE in dispersions, POE(18)TE in solubilizations and POE(50)TE in gelations were shown to be excellent which was considered due to the structural characteristic and formation of liquid crystals of POE(n)TEs. By the development and applications of these excel lent multi-functional surfactants, innovative functional cosmetics were successfully formulated.

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Neutron diffraction study on the structure of pure $TeO_2$ glass (고순도 $TeO_2$ 유리 구조의 중성자 회절 연구)

  • Toshinobu Yoko
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.5 no.2
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    • pp.189-196
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    • 1995
  • Abstract The short range structure of pure $TeO_2$ glass was studied by neutron diffraction. In order to decide the values of $Te{\cdot}O$ bond length ($d_{Te-O}$) and the coordination number $(N_{Te-O})$ of oxygen atoms surrounding a Te atom, the first peak of the $Q_{max}$ = 20, 23, 25, 28 and 30 in the highly resolved RDF curves was deconvoluted by the least - squares method under the assumption that both of the pair distribution functions have a Gaussian form On the basis of these results, it is found that pure $TeO_2$ glass consists of $TeO_4$ structural units, in which Te atoms are coordinated by four oxygens and each two oxygen atoms are bonded to a Te atom with the average bond length of 1.916 $\AA$ and 2.123 $\AA$, respectively.

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A Study on Characteristics of Phase Change in Chalcogenide Multilayered Thin Film (칼코게나이드 다층박막의 상변화 특성에 관한 연구)

  • Choi, Hyuk;Kim, Hyun-Gu;Chung, Hong-Bay
    • Proceedings of the KIEE Conference
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    • 2006.07c
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    • pp.1426-1427
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    • 2006
  • Chalcogenide based phase-change memory has a high capability and potential for the next generation nonvolatile memory device. Fast writing speed, low writing voltage, high sensing margin, low power consume and long cycle of read/write repeatability are also good advantages of nonvolatile phase-change memory. We have been investigated the new material for the phase-change memory. Its composition is consists of chalcogenide $Ge_{1}Se_{1}Te_2$ material. We made this new material to solve problems of conventional phase-change memory which has disadvantage of high power consume and high writing voltage. In the present work, we are manufactured $Ge_{1}Se_{1}Te_{2}/Ge_{2}Sb_{2}Te_{5}/Ge_{1}Se_{1}Te_{2}$ and $Ge_{2}Sb_{2}Te_{5}/Ge_{1}Se_{1}Te_{2}/Ge_{2}Sb_{2}Te_{5}$ sandwich triple layer structure devices are manufactured to investigate its electrical properties. Through the present work, we are willing to ensure a potential of substitutional method to overcome a crystallization problem on PRAM device.

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A Study on the CdTe Crystal Growth (CdTe의 결정성장에 관한 연구)

  • 박민서;이재구;정성훈;송복식;문동찬
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1995.05a
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    • pp.62-65
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    • 1995
  • CdTe crystals were grown by the vertical Bridgman method. P-type DcTe crystals were grown with Cd:Te= 1:1.001 wt. % ratio, while n-type CdTe crystals were 1:1 Also, CdTe:In crystals were investigated, Lattic constants were 6.489${\AA}$ for p-type 6.480${\AA}$for n=type and 6.483${\AA}$ for CdTe:In EPD was 10$\^$-3/-10$\^$4/cm$\^$-2/ for n-, p-type CdTd, 10$\^$4/-10$\^$5/cm$\^$-2 for Cd:Te:In using by E-Ag solution for (111) plane The carrier concentration, the resistivity and the Hall carrier mobility measured by the van der Pauw method were p=5.78${\times}$10$\^$15/cm$\^$-3/, $\rho$=20.2$\Omega$cm, ${\mu}$$\sub$p/=75.6cm$\^$-2/ V$\^$-1/ sec$\^$-1/ for p-typem n=2.98${\times}$10$\^$16/cm$\^$-3/, $\rho$=0.214$\Omega$cm, ${\mu}$$\sub$p/=978.9cm$\^$-2/ V$\^$-1/ sec$\^$-1/ for n-type and n=7.45${\times}$10$\^$16/cm$\^$-3/, $\rho$=1.54 ${\times}$10$\^$3/$\Omega$cm, ${\mu}$$\sub$p/=658.4 cm$\^$-2/ V$\^$-1/ sec$\^$-1/ for CdTe:In crystals, Transmittance of p-type CdTe was 61% that of n-type was 65%, Cd:Te:In showed 60% IR transmittance.

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Efface of Annealing in a Reduction Ambient on Thermoelectric Properties of the $(Bi,Sb)_{2}Te_{3}$ Thin Films Processed by Vacuum Evaporation (환원분위기 열처리가 $(Bi,Sb)_{2}Te_{3}$ 증착박막의 열전특성에 미치는 영향)

  • Kim, Min-Young;Oh, Tae-Sung
    • Journal of the Microelectronics and Packaging Society
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    • v.15 no.3
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    • pp.1-8
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    • 2008
  • Effects of annealing process in a reduction ambient on thermoelectric properties of the $(Bi,Sb)_{2}Te_3$ thin films prepared by thermal evaporation have been investigated. With annealing at $300^{\circ}C$ for 2 hrs in a reduction ambient(50% $H_2$+50% Ar), the crystallinity of the $(Bi,Sb)_{2}Te_3$ thin films were substantially improved with remarkable increase in the grain size. Seebeck coefficients of the $(Bi,Sb)_{2}Te_3$ thin films increased from$\sim90{\mu}V/K$ to $\sim180{\mu}V/K$ with annealing in the reduction ambient due to decrease in the hole concentration. Power factors of the $(Bi,Sb)_{2}Te_3$ thin films were remarkably improved for $5\sim16$ times with annealing in the reduction atmosphere. After annealing in the reduction ambient, a $(Bi,Sb)_{2}Te_3$ evaporated film exhibited a maximum power factor of $18.6\times10^{-4}W/K^{2}-m$.

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