Advances in theoretical understanding, numerical algorithms and computing technology have made practical the determination of electronic, vibrational and other properties from first principles, even for complex materials like advanced thermoelectrics. These approaches require a minimum of experimental input, typically only composition and crystal structure. As such they may be viewed as a new window on the materials, which in combination with experiment may lead to new insights and better understanding of the variation of properties with variables like composition. This may then lead to more efficient optimization of thermoelectric materials and help in searches for new materials. This paper illustrates how theory is being applied in the search for high ZT thermoelectrics, mostly through examples.
{"title":"Electronic and vibrational properties of skutterudites","authors":"D. J. Singh, L. Nordstrom, W. Pickett, J. Feldman","doi":"10.1109/ICT.1996.553262","DOIUrl":"https://doi.org/10.1109/ICT.1996.553262","url":null,"abstract":"Advances in theoretical understanding, numerical algorithms and computing technology have made practical the determination of electronic, vibrational and other properties from first principles, even for complex materials like advanced thermoelectrics. These approaches require a minimum of experimental input, typically only composition and crystal structure. As such they may be viewed as a new window on the materials, which in combination with experiment may lead to new insights and better understanding of the variation of properties with variables like composition. This may then lead to more efficient optimization of thermoelectric materials and help in searches for new materials. This paper illustrates how theory is being applied in the search for high ZT thermoelectrics, mostly through examples.","PeriodicalId":447328,"journal":{"name":"Fifteenth International Conference on Thermoelectrics. Proceedings ICT '96","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1996-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127205643","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}
K. Stokes, T. Tritt, W. Fuller-Mora, A. Ehrlich, R. Jacobsen
We have measured the electrical resistivity and thermoelectric power of commercial vapor-grown carbon fibers and fiber composites from 4 K to 300 K. Post-growth heat treatment decreased the resistivity and moderately increased the magnitude of the thermopower. Thermoelectric measurements on fiber composites showed that the host material altered the resistivity but had little effect on the thermopower. Thermopower data suggest that the fibers in the composite material have a smaller degree of graphitization than isolated fibers.
{"title":"Electronic transport properties of highly conducting vapor-grown carbon fiber composites","authors":"K. Stokes, T. Tritt, W. Fuller-Mora, A. Ehrlich, R. Jacobsen","doi":"10.1109/ICT.1996.553284","DOIUrl":"https://doi.org/10.1109/ICT.1996.553284","url":null,"abstract":"We have measured the electrical resistivity and thermoelectric power of commercial vapor-grown carbon fibers and fiber composites from 4 K to 300 K. Post-growth heat treatment decreased the resistivity and moderately increased the magnitude of the thermopower. Thermoelectric measurements on fiber composites showed that the host material altered the resistivity but had little effect on the thermopower. Thermopower data suggest that the fibers in the composite material have a smaller degree of graphitization than isolated fibers.","PeriodicalId":447328,"journal":{"name":"Fifteenth International Conference on Thermoelectrics. Proceedings ICT '96","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1996-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129046903","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}
Understanding the states of the metal electrode-semiconductor junctions is important for improving the performance of the thermoelectric devices. Tunneling spectroscopy has been applied to the evaluation of metal-semiconductor Schottky junctions. In this study, tunneling spectroscopy is applied to understanding the states of a metal/Bi/sub 2/Te/sub 3/ or a metal/Bi/sub 2/Se/sub 3/ junction. Bi/sub 2/Te/sub 3/ and Bi/sub 2/Se/sub 3/ single crystals were prepared by Bridgman method. The metal contacts were made on the cleavage surface of Bi/sub 2/Te/sub 3/ or Bi/sub 2/Se/sub 3/ by the thermal evaporation in the vacuum of 10/sup -3/ Pa. All tunnel conductance were measured at 4.2 K. Mg/, Al/ and Ag/Bi/sub 2/Te/sub 3/ junctions exhibit V-shaped tunnel conductance curves which indicate that these contacts ate the Schottky barrier. A Au/Bi/sub 2/Te/sub 3/ junction shows a flat conductance characteristic, so that we expect to be an ohmic contact formed in this junction. It becomes clear that the Schottky barrier is formed on the Mg/, Al/, or Ag/-Bi/sub 2/Te/sub 3/ junction. In the case of Au/ or Al/Bi/sub 2/Se/sub 3/ is also formed the Schottky barrier. Since Bi/sub 2/Te/sub 3/ and Bi/sub 2/Se/sub 3/, which are narrow energy gap semiconductors, form the Schottky barriers with those metals, the characterization of metal-semiconductor contacts is important to improve the performance of thermoelectric devices.
{"title":"Evaluation of metal-Bi2Te3 contacts by electron tunneling spectroscopy","authors":"J. Nagao, E. Hatta, K. Mukasa","doi":"10.1109/ICT.1996.553515","DOIUrl":"https://doi.org/10.1109/ICT.1996.553515","url":null,"abstract":"Understanding the states of the metal electrode-semiconductor junctions is important for improving the performance of the thermoelectric devices. Tunneling spectroscopy has been applied to the evaluation of metal-semiconductor Schottky junctions. In this study, tunneling spectroscopy is applied to understanding the states of a metal/Bi/sub 2/Te/sub 3/ or a metal/Bi/sub 2/Se/sub 3/ junction. Bi/sub 2/Te/sub 3/ and Bi/sub 2/Se/sub 3/ single crystals were prepared by Bridgman method. The metal contacts were made on the cleavage surface of Bi/sub 2/Te/sub 3/ or Bi/sub 2/Se/sub 3/ by the thermal evaporation in the vacuum of 10/sup -3/ Pa. All tunnel conductance were measured at 4.2 K. Mg/, Al/ and Ag/Bi/sub 2/Te/sub 3/ junctions exhibit V-shaped tunnel conductance curves which indicate that these contacts ate the Schottky barrier. A Au/Bi/sub 2/Te/sub 3/ junction shows a flat conductance characteristic, so that we expect to be an ohmic contact formed in this junction. It becomes clear that the Schottky barrier is formed on the Mg/, Al/, or Ag/-Bi/sub 2/Te/sub 3/ junction. In the case of Au/ or Al/Bi/sub 2/Se/sub 3/ is also formed the Schottky barrier. Since Bi/sub 2/Te/sub 3/ and Bi/sub 2/Se/sub 3/, which are narrow energy gap semiconductors, form the Schottky barriers with those metals, the characterization of metal-semiconductor contacts is important to improve the performance of thermoelectric devices.","PeriodicalId":447328,"journal":{"name":"Fifteenth International Conference on Thermoelectrics. Proceedings ICT '96","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1996-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123050514","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}
The dependence of thermoelectric properties on the texture layer thickness was investigated. The electric and thermal conductivities decrease is caused by decrease of texture layer thickness. Seebeck coefficient and figure of merit remain constant.
{"title":"Texture influence on the forming of thermoelectric properties of pressed semiconductors","authors":"L. Anatychuk, S. V. Kosyachenko, S. V. Melnichuk","doi":"10.1109/ICT.1996.553292","DOIUrl":"https://doi.org/10.1109/ICT.1996.553292","url":null,"abstract":"The dependence of thermoelectric properties on the texture layer thickness was investigated. The electric and thermal conductivities decrease is caused by decrease of texture layer thickness. Seebeck coefficient and figure of merit remain constant.","PeriodicalId":447328,"journal":{"name":"Fifteenth International Conference on Thermoelectrics. Proceedings ICT '96","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1996-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122703303","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. A. Aivazov, Y.I. Stern, K. Makhratchev, A.V. Morgal
The paper describes the problems of design and construction development of thermoelectric (TH) air chillers for different means of transport. The report contains the description of the temperature operating conditions of TH air chillers and the procedures of the TH air chiller testing. The results of the stand operation of the TH air chiller at various voltages are analyzed. The paper highlights TH module mathematical modeling by means of equations account for the variation of the main TH properties across the thermocouple with the temperature gradient. The modeling of TH module operation is based on the numerical solution of a second order nonlinear differential equation. The solution obtained is compared with the results from a crude method and from the stand testing.
{"title":"The design problems of thermoelectric heat pumps for transportation facilities","authors":"A. A. Aivazov, Y.I. Stern, K. Makhratchev, A.V. Morgal","doi":"10.1109/ICT.1996.553310","DOIUrl":"https://doi.org/10.1109/ICT.1996.553310","url":null,"abstract":"The paper describes the problems of design and construction development of thermoelectric (TH) air chillers for different means of transport. The report contains the description of the temperature operating conditions of TH air chillers and the procedures of the TH air chiller testing. The results of the stand operation of the TH air chiller at various voltages are analyzed. The paper highlights TH module mathematical modeling by means of equations account for the variation of the main TH properties across the thermocouple with the temperature gradient. The modeling of TH module operation is based on the numerical solution of a second order nonlinear differential equation. The solution obtained is compared with the results from a crude method and from the stand testing.","PeriodicalId":447328,"journal":{"name":"Fifteenth International Conference on Thermoelectrics. Proceedings ICT '96","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1996-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128469094","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}
Factors, which promote microminiaturization of cooling modules have been considered. Results of thermoelectric cooler investigations are presented taking into account all classical factors: electrical and heat resistance of a commutation, contact resistance, heat resistance of heat transfers, all kinds of thermoelectric effects, temperature dependencies of material properties, etc. The influence of all factors on cooling efficiency is analyzed. New factors, which can have influence on a module work, namely strong electric field, large temperature gradient, size effects, and diffusion processes are considered. The influence on microminiaturization and conditions for these factors actions are analyzed. A common analysis for microminiaturization limits and a prognosis of thermoelectric modules development is presented.
{"title":"Physical principles of microminiaturization in thermoelectricity","authors":"L. Anatychuk, O. Luste","doi":"10.1109/ICT.1996.553318","DOIUrl":"https://doi.org/10.1109/ICT.1996.553318","url":null,"abstract":"Factors, which promote microminiaturization of cooling modules have been considered. Results of thermoelectric cooler investigations are presented taking into account all classical factors: electrical and heat resistance of a commutation, contact resistance, heat resistance of heat transfers, all kinds of thermoelectric effects, temperature dependencies of material properties, etc. The influence of all factors on cooling efficiency is analyzed. New factors, which can have influence on a module work, namely strong electric field, large temperature gradient, size effects, and diffusion processes are considered. The influence on microminiaturization and conditions for these factors actions are analyzed. A common analysis for microminiaturization limits and a prognosis of thermoelectric modules development is presented.","PeriodicalId":447328,"journal":{"name":"Fifteenth International Conference on Thermoelectrics. Proceedings ICT '96","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1996-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131406374","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}
The investigation results of rational fields of single- and two-stage thermoelectric cooling module use, in the context of their energetic efficiency and economical utility in refrigeration applications, are presented by the authors.
从单级和双级热电制冷模块在制冷应用中的能量效率和经济效用的角度出发，对其合理应用领域进行了调查。
{"title":"Rational conditions and prospects for two-stage cooling modules use","authors":"L. Anatychuk, L. Vikhor, K. Misawa, N. Suzuki","doi":"10.1109/ICT.1996.553321","DOIUrl":"https://doi.org/10.1109/ICT.1996.553321","url":null,"abstract":"The investigation results of rational fields of single- and two-stage thermoelectric cooling module use, in the context of their energetic efficiency and economical utility in refrigeration applications, are presented by the authors.","PeriodicalId":447328,"journal":{"name":"Fifteenth International Conference on Thermoelectrics. Proceedings ICT '96","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1996-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132984266","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}
Mg/sub 2/Si/sub 1-x/Sn/sub x/ solid solutions with (0/spl les/x/spl les/0.4) were prepared by mechanical alloying and subsequent hot-pressing. It was found that the alloying process during milling develops in one of two different directions. The first one leads to the nominal composition with only a small amount of iron impurities resulting from wear of the milling media. In the second route-which only occurs in the presence of Sn-an abrasive phase is formed and the Fe content may increase up to 50 at%. The Fe is bound in FeSi and consequently, the solid solution has a lack of Si. The hot-pressing was performed at a temperature smaller than the peritectic temperature of the quasibinary Mg/sub 2/Si-Mg/sub 2/Sn system. A decomposition of the solid solutions occurs, which suggest changes on the miscibility gap in published phase diagrams. However, some transport measurements on the multiphase materials were performed, which revealed lower mobility values and lattice thermal conductivities compared to values published in the literature for single crystalline materials. The mobility of our materials was found to be independent from composition whereas the thermal conductivity decreases with increasing Sn content.
{"title":"Mechanically alloyed Mg2Si/sub 1-x/Snx solid solutions as thermoelectric materials","authors":"M. Riffel, J. Schilz","doi":"10.1109/ICT.1996.553275","DOIUrl":"https://doi.org/10.1109/ICT.1996.553275","url":null,"abstract":"Mg/sub 2/Si/sub 1-x/Sn/sub x/ solid solutions with (0/spl les/x/spl les/0.4) were prepared by mechanical alloying and subsequent hot-pressing. It was found that the alloying process during milling develops in one of two different directions. The first one leads to the nominal composition with only a small amount of iron impurities resulting from wear of the milling media. In the second route-which only occurs in the presence of Sn-an abrasive phase is formed and the Fe content may increase up to 50 at%. The Fe is bound in FeSi and consequently, the solid solution has a lack of Si. The hot-pressing was performed at a temperature smaller than the peritectic temperature of the quasibinary Mg/sub 2/Si-Mg/sub 2/Sn system. A decomposition of the solid solutions occurs, which suggest changes on the miscibility gap in published phase diagrams. However, some transport measurements on the multiphase materials were performed, which revealed lower mobility values and lattice thermal conductivities compared to values published in the literature for single crystalline materials. The mobility of our materials was found to be independent from composition whereas the thermal conductivity decreases with increasing Sn content.","PeriodicalId":447328,"journal":{"name":"Fifteenth International Conference on Thermoelectrics. Proceedings ICT '96","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1996-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131090270","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}
D. Compton, A. Leitch, J. Neethling, V. V. Kozyrkov
This paper reports on a structural investigation of the ternary compound TiNiSn, prepared as a thin film by electron beam deposition of a sandwich structure comprising individual layers of Ti, Ni and Sn. The effect of annealing the compound at 800/spl deg/C for times up to 72 hours was investigated. X-ray diffraction revealed the formation of TiNi/sub 2/Sn after 6 hours of annealing. The excess of Ni in the deposited structure (confirmed by EDS) resulted in the first phase of TiNiSn not being present and a shift in the lattice parameter of second phase TiNi/sub 2/Sn.
{"title":"A microstructural analysis of thin film TiNiSn","authors":"D. Compton, A. Leitch, J. Neethling, V. V. Kozyrkov","doi":"10.1109/ICT.1996.553533","DOIUrl":"https://doi.org/10.1109/ICT.1996.553533","url":null,"abstract":"This paper reports on a structural investigation of the ternary compound TiNiSn, prepared as a thin film by electron beam deposition of a sandwich structure comprising individual layers of Ti, Ni and Sn. The effect of annealing the compound at 800/spl deg/C for times up to 72 hours was investigated. X-ray diffraction revealed the formation of TiNi/sub 2/Sn after 6 hours of annealing. The excess of Ni in the deposited structure (confirmed by EDS) resulted in the first phase of TiNiSn not being present and a shift in the lattice parameter of second phase TiNi/sub 2/Sn.","PeriodicalId":447328,"journal":{"name":"Fifteenth International Conference on Thermoelectrics. Proceedings ICT '96","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1996-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130644193","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. Heinrich, A. Burkov, C. Gladun, G. Behr, K. Herz, J. Schumann, H. Powalla
Thermopower and electrical resistivity have been investigated of /spl beta/-FeSi/sub 2/ single crystals and /spl beta/-FeSi/sub 2+x/ thin films in the temperature range from 40 K to 1200 K. The single crystals were grown by chemical transport reaction with source material of different purity and with a Si/Fe ratio between 1.5 and 2.5 to obtain crystals from the Fe-rich and Si-rich boundaries of the homogeneity range, respectively. The undoped and co-doped thin films have been prepared in the range -0.06
{"title":"Thermopower and electrical resistivity of undoped and co-doped /spl beta/-FeSi2 single crystals and /spl beta/-FeSi2+x thin films","authors":"A. Heinrich, A. Burkov, C. Gladun, G. Behr, K. Herz, J. Schumann, H. Powalla","doi":"10.1109/ICT.1996.553256","DOIUrl":"https://doi.org/10.1109/ICT.1996.553256","url":null,"abstract":"Thermopower and electrical resistivity have been investigated of /spl beta/-FeSi/sub 2/ single crystals and /spl beta/-FeSi/sub 2+x/ thin films in the temperature range from 40 K to 1200 K. The single crystals were grown by chemical transport reaction with source material of different purity and with a Si/Fe ratio between 1.5 and 2.5 to obtain crystals from the Fe-rich and Si-rich boundaries of the homogeneity range, respectively. The undoped and co-doped thin films have been prepared in the range -0.06<x<0.25 by coevaporation. It is shown that the conductivity type of the single crystals changes from p-type to n-type with increasing purity of the starting material. Both thermopower and resistivity depend on the deviation from strict stoichiometry. The low temperature thermopower is mainly determined by phonon drag effect. The undoped films are of p-type. It is shown that the films are especially sensitive to doping at x/spl ap/0.13.","PeriodicalId":447328,"journal":{"name":"Fifteenth International Conference on Thermoelectrics. Proceedings ICT '96","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1996-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123898280","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}
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