Papers by Keyword: Thermoelectric

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Authors: Yosuke Murayama, Hideyuki Homma, Shigeo Yamaguchi
Abstract: This study is to measure accurate temperature at a point which is cooled and heated. We proposed and fabricated a new Peltier device with a coaxial thermocouple composed of constantan and copper. Current dependence of temperature of the head of the coaxial thermocouple was measured, and it was shown that in cooling operation, the difference between designated temperatures and calibrated ones was as small as within 1°C.
Authors: Yoko Okuwaki, Shigeo Yamaguchi
Abstract: We have studied a novel Peltier device having a metallic tip which is directly sandwiched between P-type and N-type thermoelectric materials. The tip can be heated and cooled directly driven by Peltier effect, resulting in high thermal response. In this study, we report the fabrication of a portable thermal cycler using a PN sandwich-structure Peltier device. The device has copper plates with minute fin to efficiently radiate heat.
Authors: Hasan Aydogan, A. Engin Ozcelik, Mustafa Acaroglu, Hakan Işik
Abstract: Internal combustion engines are widely used in our day. Internal combustion engines first transform fuel energy into heat energy. Afterwards, approximately 30% of this heat energy is transformed into mechanical energy. Approximately 5% of the heat energy is expelled through friction and radiation, 30% through cooling and 35% through the exhaust system. In the present study, electricity was generated by using thermoelectric equipment and the waste heat expelled from the exhaust system. It was observed that as the exhaust temperature increased, the amount of electricity generated also increased.
Authors: Zurianti A. Rahman, Khaulah Sulaiman, Mohamad Rusop, Ahmad Shuhaimi
Abstract: The studies on the thermoelectric (TE) properties of 3,4,9,10-Perylenetetracarboxylic dianhydride (PTCDA) and a conducting polymer Poly(ethylenedioxythiopene): poly(styrenesulfonate) (PEDOT:PSS)–PH1000 are presented. PTCDA and PEDOT:PSS have been used as a potential n-type material and a p-type material for the TE device, respectively. The Seebeck coefficients, open circuit voltage and the output power have been obtained for the fabricated TE device. The Seebeck effect was observed on this TE device where the output power in the range of 1 nW/cm2 to 5 nW/cm2,was successfully deduced from this TE device. It was found that the association of PEDOT:PSS and PTCDA have been acting well in this TE device. However, a higher TE performance, in the future could be developed, by applying a thermal treatment and introducing a suitable dopant to this n-type material which may increase the mobility of the electrons and the Seebeck coefficient.
Authors: J. Kouvetakis, Jose Menendez, John Tolle
Abstract: Group-IV semiconductors, including alloys incorporating Sn, have been grown on dimensionally dissimilar Si substrates using novel molecular hydride chemistries with tunable reactivities that enable low temperature, CMOS compatible integration via engineering of the interface microstructure. Here we focus on properties of three such Ge-based systems including: (1) device quality Ge layers with thicknesses >5m possessing dislocation densities <105/cm2 are formed using molecular mixtures of Ge2H6 and highly reactive (GeH3)2CH2 organometallic additives circumventing the classical Stranski-Krastanov growth mechanism, (2) metastable GeSn alloys are grown on Si via reactions of Ge2H6 and SnD4, and (3) ternary SiGeSn analogs are produced lattice-matched to Ge-buffered Si using admixtures of SiGeH6, SiGe2H8, SnD4, Ge2H6, and Si3H8. Optical experiments and prototype device fabrication demonstrate that the ternary SiGeSn system represents the first group-IV alloy with a tunable electronic structure at fixed lattice constant, effectively decoupling band gap and strain and eliminating the most important limitation in device designs based on group-IV materials. Doping at levels higher than 1019 cm-3 (both p and n-type) is achieved for all the above semiconductor systems using a similar precursor chemistry approach. Electrical and infrared optical experiments demonstrate that doped GeSn and SiGeSn have mobilities that compare or exceed that of bulk Ge. The potential applications of these materials, including micro- and optoelectronics as well as photovoltaics and thermoelectricity, are discussed.
Authors: Wang Kee Min, Sung Doo Hwang, Chang Ho Lee, Young Do Park, Yang Do Kim, Young Seok Kim, Ik Min Park, Yong Ho Park
Abstract: The n-type Bi2(Te0.94Se0.06)3 thermoelectric compound was prepared by the direct extrusion process using the powder as raw materials. Hot extruded specimens were annealed at 200°C and 350°C for 2hrs. The electrical conductivity, thermoelectric power and thermal conductivity of hot extruded and annealed specimens were measured at room temperature. The fractographs of the specimens showed that the grain size became coarser and a lot of porosities were generated during annealing process. The power factor value (PF) decreased with increasing the annealing temperature. The electric conductivity and thermal conductivity of the specimens also decreased with the increase of annealing temperature. This may be reasoned that the generated porosities affect the thermal conductivity of the specimens prepared in this study. The figure of merit (Z) value of the annealed specimens at 350°C was improved about 10%. The highest Z value of the specimens annealed at 350°C was 2.0 x 10-3/K among the prepared specimens.
Authors: Il Ho Kim, Jung Il Lee, Soon Chul Ur, Kyung Wook Jang, Good Sun Choi, Joon Soo Kim
Abstract: Binary skutterudite CoSb3 compounds were prepared by the arc melting and hot pressing processes and their thermoelectric properties were investigated at 300K-600K. Annealing effect was examined and it was correlated to phase transformation and homogenization. Thermoelectric properties of the arc-melted and hot-pressed CoSb3 were discussed and compared. Undoped CoSb3 prepared by the arc melting showed p-type conduction and metallic behavior at all temperatures examined. 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 transitions.
Authors: Y. Gelbstein, Z. Dashevsky, R. Kreizman, Y. George, M. Gelbstein, M.P. Dariel
Abstract: Lead tin telluride based alloys are known p-type materials for thermoelectric applications, in the 50-600oC temperature range. These alloys combine desired features of mechanical and thermoelectric properties. The electronic transport properties of PbTe and Pb1-xSnxTe materials may be strongly dependent on the preparation technique. Powder metallurgy process is known to introduce defects and strains, that may alter carrier concentration. Under such non-equilibrium conditions the thermoelectric properties are instable at the operating temperature. An appropriate annealing treatment can eliminate this effect.. The present communication describes the annealing treatment applied to cold compacted and sintered Pb1-xSnxTe materials.
Authors: Hyun Jae Yoo, Chang Ho Lee, Yong Ho Park, Ik Min Park
Abstract: Effect of Au (0-0.3 wt.%) on the thermoelectric properties of Bi1Sb3Te6 alloy prepared by mechanical alloying process has been investigated. The Seebeck coefficient decreases with Au content. The Seebeck coefficient of Au-free alloy at room temperature reaches a value of 250 µV/K, which is the maximum. Because of the increased power factor, the figure of merit increases with Au content up to 0.03 wt. % and its value at room temperature is about 2.8×10-3/K, the highest value among the prepared alloys. The Hall measurement shows that the carrier concentration increases with Au content, which explains the reason why the power factor has increased. The XRD patterns show that the intensities of (2 0 5), (0 0 18), (0 2 10), (1 0 19), (1 2 5), and (2 1 10) planes increase with Au content. The atomic distance of these complex planes is longer than that of other main planes, and the chemical bonding strength of these complex planes between constitutional elements is weaker than that of other main planes. As a result, a portion of electrons as minor carrier is trapped into accept level of Au atoms and/or clusters. The XPS observation result, which a portion of Au atoms is chemically shifted in contrast to Bi, Sb and Te atoms are not, explains that Au behaves as an acceptor.
Authors: Kazuki Tajima, Woosuck Shin, Maiko Nishibori, Norimitsu Murayama, Toshio Itoh, Noriya Izu, Ichiro Matsubara
Abstract: Micro-thermoelectric hydrogen sensor (micro-THS) with the combination of the thermoelectric effect of Si0.8Ge0.2 thin film and the Pt-catalyzed exothermic reaction of hydrogen oxidation was prepared by microfabrication process. In the viewpoint of high sensitivity of micro-THS, the thermoelectric properties of the Si0.8Ge0.2 thin film could be improved by optimizing carrier concentration using helicon sputtering with an advantage of easy doping control, and sensitivity of the device with this thin film was investigated. As the result, the boron-doped Si0.8Ge0.2 thin film is considered to be the better choice ensuring the reliable monitoring of hydrogen concentration down to ppm level.
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