Jeongha Kim, Sung-Do Kwon, D. Jeong, B. Ju, Seok-Jin Yoon, Jin-Sang Kim
{"title":"Structural Characteristics of Bi2Te3 and Sb2Te3 films on (001) GaAs Substrates grown by MOCVD","authors":"Jeongha Kim, Sung-Do Kwon, D. Jeong, B. Ju, Seok-Jin Yoon, Jin-Sang Kim","doi":"10.1109/ICT.2006.331284","DOIUrl":"https://doi.org/10.1109/ICT.2006.331284","url":null,"abstract":"Metal organic vapour phase epitaxy has been investigated for growth of Bi<sub>2</sub>Te<sub>3</sub> and Sb<sub>2</sub>Te<sub>3</sub> films on (001) GaAs substrates using trimethylbismuth, triethylantimony and diisopropyltelluride as metal organic sources. High resolution TEM and X-ray diffraction patterns revealed that films had single crystalline phases with a preferential c-orientation and layered structures resulting from the van der Waals bonding nature in these materials. By optimizing growth parameters such as precursor ratio, growth temperatures, and flow rate in reactor, we could obtain Seebeck coefficient of -160muVK<sup>-1</sup> for Bi<sub>2</sub>Te<sub>3</sub> and +110muVK<sup>-1</sup> for Sb<sub>2</sub>Te<sub>3</sub> films, respectively. The high Seebeck coefficient and atomistically smooth surface morphologies of these materials are promising for the fabrication of a few nm thick periodic Bi<sub>2</sub>Te<sub>3</sub>/Sb <sub>2</sub>Te<sub>3</sub>super lattice structures for thin film thermoelectric device applications","PeriodicalId":346555,"journal":{"name":"2006 25th International Conference on Thermoelectrics","volume":"131 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122489349","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"High temperature thermoelectric properties of Czochralski-pulled Ba8Ga16Ge30","authors":"M. Christensen, G. J. Snyder, B. Iversen","doi":"10.1109/ICT.2006.331265","DOIUrl":"https://doi.org/10.1109/ICT.2006.331265","url":null,"abstract":"High temperature thermoelectric properties have been measured on a Czochralski pulled Ba8Ga16Ge30 crystal. Complete transport properties obtained in the temperature range from 273K to 1150K. The physical properties are reproducible even after thermal cycling. The Seebeck coefficient reveals the sample to be an n-type conductor with a maximum value of -148 muV/K at 1073K. The electrical resistivity shows the characteristics of a heavily doped semi conductor, and it goes through a maximum at 1073 K with a value of 1.7 mOmega-cm. The thermal conductivity goes through a minimum of 1.25 W/m-K around 900K, and ZT reaches a maximum of 0.9 at 1000 K","PeriodicalId":346555,"journal":{"name":"2006 25th International Conference on Thermoelectrics","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131351448","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
T. Kyratsi, E. Hatzikraniotis, A. Tsiappos, K. Paraskevopoulos, M. Kanatzidis
{"title":"n-to-p Transition on K2Bi8-xSbxSe13 Series","authors":"T. Kyratsi, E. Hatzikraniotis, A. Tsiappos, K. Paraskevopoulos, M. Kanatzidis","doi":"10.1109/ICT.2006.331383","DOIUrl":"https://doi.org/10.1109/ICT.2006.331383","url":null,"abstract":"beta-K<sub>2</sub>Bi<sub>8</sub>Se<sub>13</sub> and its solid solutions have been found to be interesting for thermoelectric investigations mainly due to their low thermal conductivity and highly anisotropic electrical properties. Solid solution series of the type K <sub>2</sub>Bi<sub>8-x</sub>Sb<sub>x</sub>Se<sub>13</sub>, K<sub>2-x </sub>Rb<sub>x</sub>Bi<sub>8</sub>Se<sub>13</sub> as well as K<sub>2 </sub>Bi<sub>8</sub>Se<sub>13-x</sub>S<sub>x</sub> has been studied. Interestingly, K<sub>2</sub>Bi<sub>8-x</sub>Sb<sub>x</sub>Se<sub>13</sub> presents both n- and p-type of character depending on the Sb concentration in the lattice. In this work, the n-to-p transition with Sb concentration is presented. The Seebeck coefficient is discussed as a function of x and the transition at room temperature appears at the stoichiometric region of x ~ 6. The transition temperature for the members of the series increases with Sb incorporation in the lattice and this can be attributed to the band gap increase","PeriodicalId":346555,"journal":{"name":"2006 25th International Conference on Thermoelectrics","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133850853","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Optimization of synthesis conditions for CoSb3 compounds prepared by Sb self-flux method","authors":"T. Souma, M. Ohtaki","doi":"10.1109/ICT.2006.331385","DOIUrl":"https://doi.org/10.1109/ICT.2006.331385","url":null,"abstract":"CoSb3 bulk materials were successfully prepared by Sb self-flux technique, and the synthesis conditions were widely investigated to obtain the high purity compounds utilizing a quantitative powder XRD study with the Rietveld analysis applying a multi-phase-fitting condition. The reaction temperature range for the Sb self-flux technique was extended up to 1123 K to promote the reaction in the Co-Sb system. The relation between the reaction temperature and the chemical composition is discussed to optimize the preparation conditions in the Sb self-flux technique","PeriodicalId":346555,"journal":{"name":"2006 25th International Conference on Thermoelectrics","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126984900","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
H. Kuriyama, M. Nohara, T. Sasagawa, K. Takubo, T. Mizokawa, K. Kimura, H. Takagi
{"title":"High-temperature thermoelectric properties of Delafossite oxide CuRh1-xMgxO2","authors":"H. Kuriyama, M. Nohara, T. Sasagawa, K. Takubo, T. Mizokawa, K. Kimura, H. Takagi","doi":"10.1109/ICT.2006.331289","DOIUrl":"https://doi.org/10.1109/ICT.2006.331289","url":null,"abstract":"We report high temperature thermoelectric properties of doped Delafossite oxide CuRh<sub>1-x</sub>Mg<sub>x</sub>O<sub>2</sub>. The parent compound CuRhO<sub>2</sub> is a band insulator and becomes metallic upon Mg doping for Rh. We found that polycrystalline CuRh<sub>1-x</sub>Mg<sub>x</sub>O<sub>2</sub> shows a large thermoelectric power S ~ +270 muV/K despite its low resistivity ~6 mOmegacm at high temperatures around 1000 K. Combining these with a thermal conductivity kappa ~ 80 mW/cm K, we estimate a large dimensionless figure of merit ZT 7sim; 0.15 at 1000 K","PeriodicalId":346555,"journal":{"name":"2006 25th International Conference on Thermoelectrics","volume":"95 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123431509","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Thermoelectric Properties of Pressed Pellets and Pressureless Sintering in the K2Bi8Se13-xSx System","authors":"A. Tsiappos, T. Kyratsi, M. Kanatzidis","doi":"10.1109/ICT.2006.331346","DOIUrl":"https://doi.org/10.1109/ICT.2006.331346","url":null,"abstract":"The solid solutions of beta-K<sub>2</sub>Bi<sub>8</sub>Se<sub>13 </sub> are an interesting series of materials for thermoelectric investigations because they possess very low thermal conductivity and relatively high power factor. Moreover, the sulfur-substituted K<sub>2 </sub>Bi<sub>8</sub>Se<sub>13-x</sub>S<sub>x</sub> compounds were found to have promising properties showing the potential for high temperature applications. Due to their high anisotropic properties, we aim to develop polycrystalline pellets and study their thermoelectric properties as well as their potential to achieve promising power factor. In this work, for the first time pressed pellet samples of the K<sub>2 </sub>Bi<sub>8</sub>Se<sub>13</sub> system are presented. The morphology of the material and the thermoelectric properties of pressed pellets of the K<sub>2</sub>Bi<sub>8</sub>Se<sub>13-x</sub>S<sub>x</sub> compounds were studied in terms of sintering conditions","PeriodicalId":346555,"journal":{"name":"2006 25th International Conference on Thermoelectrics","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125806515","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Relation between zn content and thermoelectric properties of zn4+xsb3 (-0.12⩽x⩽0.12)","authors":"T. Souma, M. Ohtaki","doi":"10.1109/ICT.2006.331384","DOIUrl":"https://doi.org/10.1109/ICT.2006.331384","url":null,"abstract":"A series of seven bulk crystals of Zn<sub>4+x</sub>Sb<sub>3</sub> (-0.12 ⩽ x ⩽ 0.12) are successfully prepared, and the relation between the Zn content and the thermoelectric properties is investigated. The sample with the nominal composition of Zn<sub>3.96 </sub>Sb<sub>3</sub> (x = -0.04) contain the maximum mass fraction of Zn <sub>4</sub>Sb<sub>3</sub>. The shapes of the S(T) and ρ(T) curves are drastically changed with varying x in the temperature range from 300 K to 700 K. Whereas the lower x leads to lower ρ, the magnitude of S unchanges, resulting in the fact that the power factor of the Zn-poor compositions in the Zn<sub>4+x</sub>Sb<sub>3</sub> system is lower than that of the Zn-rich compositions. The details of the influence of the Zn content and the scope of the improvement of the durability are discussed.","PeriodicalId":346555,"journal":{"name":"2006 25th International Conference on Thermoelectrics","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128290743","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Enhanced Thermoelectric Performance of Nanostructured ZnO: A possibility of selective phonon scattering and carrier energy filtering by nanovoid structure","authors":"M. Ohtaki, R. Hayashi","doi":"10.1109/ICT.2006.331368","DOIUrl":"https://doi.org/10.1109/ICT.2006.331368","url":null,"abstract":"Highly dispersed nanosized closed pores (nanovoids) are revealed to be effective to substantially enhance the thermoelectric performance of bulk sintered body of n-type Al-doped ZnO oxide, resulting in a dimensionless figure-of-merit of ZT = 0.65 at 1250 K. The nanovoid structure is built in a densely sintered Al-doped ZnO matrix by using combustible nanosized polymer particles as a void forming agent (VFA), the uniformity of the VFA distribution in the sintering mixture being greatly improved by employing planetary-type ball milling with high pulverizing capability. A combination of shortened mixing period and liquid mixing media enables us to prevent formation of oxygen-related defects in ZnO, and sintered samples thus obtained show the electrical conductivity (sigma) higher than that of those prepared with conventional ball milling. The sintered samples obtained in the present study also show the Seebeck coefficient (S) considerably larger than that of the control sample over the whole temperature range from 300 K to 1273 K, implying an enhancement of the thermopower possibly due to a carrier energy filtering effect by low-energy nanosized defects. Although a decrease in the thermal conductivity (kappa) is only of the same magnitude to that of the sigma values, the marked increase in both sigma and S gives rise to a significant enhancement of the power factor. With fairly suppressed kappa values, the nanovoid ZnO samples successfully attain a largest ZT value so far observed for n-type bulk oxide materials","PeriodicalId":346555,"journal":{"name":"2006 25th International Conference on Thermoelectrics","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122561276","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Mavrokefalos, M. Pettes, S. Saha, F. Zhou, Li Shi
{"title":"Combined Thermoelectric and Structure Characterizations of Patterned Nanowires","authors":"A. Mavrokefalos, M. Pettes, S. Saha, F. Zhou, Li Shi","doi":"10.1109/ICT.2006.331358","DOIUrl":"https://doi.org/10.1109/ICT.2006.331358","url":null,"abstract":"Theoretical studies have suggested that Bi-based and III-V nanowire structures may have high thermoelectric figure of merit (ZT). It was found in a previous measurement that the thermoelectric properties of individual electro-deposited bismuth telluride nanowires are largely influenced by the crystal structure including crystalline quality, chemical composition, doping concentration, and surface roughness, all of which cannot be controlled readily in various bottom-up nanowire synthesis method. We have developed a top-down fabrication process of suspended indium arsenide (InAs) nanowires. Based on nanolithography and reactive ion etching, the nanowires are patterned from an epitaxial thin film deposited by molecular beam epitaxy with well-controlled doping concentration, which can be determined from Hall measurement. The thermoelectric properties of these top-down patterned III-V nanowires have been characterized using a new design of a suspended microdevice. The new device allows for transmission electron microscopy and energy dispersive X-ray spectroscopy analysis of the same nanowire assembled on the microdevice so as to establish the structure-thermoelectric properties relationships. This paper reports the measured thermoelectric properties of a patterned InAs nanowire with a rectangular cross section of 150 nm in width and 40 nm thickness in a temperature range between 100 K and 400 K. The obtained Seebeck coefficient, thermal conductivity, electrical conductivity, and ZT are -57.2 muV/K, 4.11 W/m K, 1350 S/m, and 0.00032, respectively, at temperature 300 K","PeriodicalId":346555,"journal":{"name":"2006 25th International Conference on Thermoelectrics","volume":"71 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114526662","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
T. Ikeda, V. Ravi, L. A. Collins, S. Haile, G. J. Snyder
{"title":"Development of Nanostructures in Thermoelectric Pb-Te-Sb Alloys","authors":"T. Ikeda, V. Ravi, L. A. Collins, S. Haile, G. J. Snyder","doi":"10.1109/ICT.2006.331326","DOIUrl":"https://doi.org/10.1109/ICT.2006.331326","url":null,"abstract":"In analogy to recent demonstrations of enhanced thermoelectric properties in superlattice materials, composite structures with nanoscale features promise dramatic improvements in the figure of merit of thermoelectric materials. Fabrication of nanostructured thermoelectric materials via bulk synthesis is an attractive route for commercial applications. Nanometer scale lamellae of PbTe and Sb2 Te3 form when quenched eutectic PbTe-Sb2Te 3 melt is subsequently annealed. The lamellar spacing depends on the temperature and time of the anneal. The mechanism for the development of the nanostructures can be characterized by examining the fraction of material transformed as a function of anneal time. Preliminary analysis of the shape factor exponent reveals that the evolution of the nanostructured lamellae is likened to the thickening of very large plates. The coarsening of the lamellar spacing is also examined as a function of time","PeriodicalId":346555,"journal":{"name":"2006 25th International Conference on Thermoelectrics","volume":"394 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2006-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132347990","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}