Pub Date : 2005-06-19DOI: 10.1109/ICT.2005.1519916
K. Goto, K. Kurosaki, A. Kosuga, H. Muta, S. Yamanaka
We prepared high-density polycrystalline samples of Cu/sub 2/Te, Tl/sub 2/Te, and CuTl/sub 9/Te/sub 5/, and measured the thermoelectric properties. The thermal conductivity of CuTl/sub 9/Te/sub 5/ is very low, 0.49 Wm/sup -1/K/sup -1/ at room temperature. CuTl/sub 9/Te/sub 5/ indicates the relatively high figure of merit ZT because of its very low thermal conductivity. The highest ZT value is 0.38 obtained at 590 K for CuTl/sub 9/Te/sub 5/.
{"title":"Thermoelectric properties of ternary copper thallium telluride: CuTl/sub 9/Te/sub 5/","authors":"K. Goto, K. Kurosaki, A. Kosuga, H. Muta, S. Yamanaka","doi":"10.1109/ICT.2005.1519916","DOIUrl":"https://doi.org/10.1109/ICT.2005.1519916","url":null,"abstract":"We prepared high-density polycrystalline samples of Cu/sub 2/Te, Tl/sub 2/Te, and CuTl/sub 9/Te/sub 5/, and measured the thermoelectric properties. The thermal conductivity of CuTl/sub 9/Te/sub 5/ is very low, 0.49 Wm/sup -1/K/sup -1/ at room temperature. CuTl/sub 9/Te/sub 5/ indicates the relatively high figure of merit ZT because of its very low thermal conductivity. The highest ZT value is 0.38 obtained at 590 K for CuTl/sub 9/Te/sub 5/.","PeriodicalId":422400,"journal":{"name":"ICT 2005. 24th International Conference on Thermoelectrics, 2005.","volume":"546 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115634679","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}
Pub Date : 2005-06-19DOI: 10.1109/ICT.2005.1519958
Y. Meydbray, R. Singh, A. Shakouri
Energy related carbon dioxide emissions are the largest contributors to greenhouse gasses [1]. Thermoelectric power generation that exploits natural temperature differences between the air and earth can be a zero-emission replacement to small stand-alone power sources. Maximizing the temperature drop across the module is crucial to achieving optimal output power. An equation relating output power to thermoelectric module parameters is derived. In addition, several configurations are investigated experimentally. Output power shows a significant dependence on module surface area. In the setups tested, one side of the thermoelectric module was thermally coupled to the earth, while the other side was left exposed to air. This paper evaluates three 110hour experiments. The surface area of the exposed side was varied by a factor of about 15 without changing the area covered by thermoelectric elements. The output power shows a direct dependence on exposed surface area and changes by about a factor of 25. Nomenclature S surface area of module A cross sectional area covered by elements KA thermal conductivity of air Ke thermal conductivity of elements ρ resistivity of elements q heat transfer through module q’ heat transfer from module to air U heat transfer coefficient TA air temperature TC cold side temperature TH hot side temperature L element length α Seebeck coefficient Rtot. total thermal resistance of module N number of elements
{"title":"Thermoelectric module construction for low temperature gradient power generation","authors":"Y. Meydbray, R. Singh, A. Shakouri","doi":"10.1109/ICT.2005.1519958","DOIUrl":"https://doi.org/10.1109/ICT.2005.1519958","url":null,"abstract":"Energy related carbon dioxide emissions are the largest contributors to greenhouse gasses [1]. Thermoelectric power generation that exploits natural temperature differences between the air and earth can be a zero-emission replacement to small stand-alone power sources. Maximizing the temperature drop across the module is crucial to achieving optimal output power. An equation relating output power to thermoelectric module parameters is derived. In addition, several configurations are investigated experimentally. Output power shows a significant dependence on module surface area. In the setups tested, one side of the thermoelectric module was thermally coupled to the earth, while the other side was left exposed to air. This paper evaluates three 110hour experiments. The surface area of the exposed side was varied by a factor of about 15 without changing the area covered by thermoelectric elements. The output power shows a direct dependence on exposed surface area and changes by about a factor of 25. Nomenclature S surface area of module A cross sectional area covered by elements KA thermal conductivity of air Ke thermal conductivity of elements ρ resistivity of elements q heat transfer through module q’ heat transfer from module to air U heat transfer coefficient TA air temperature TC cold side temperature TH hot side temperature L element length α Seebeck coefficient Rtot. total thermal resistance of module N number of elements","PeriodicalId":422400,"journal":{"name":"ICT 2005. 24th International Conference on Thermoelectrics, 2005.","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128979742","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}
Pub Date : 2005-06-19DOI: 10.1109/ICT.2005.1519930
Yan Zhang, Z. Bian, A. Shakouri
In this paper, we investigate the effect of the thermoelectric leg geometry and boundary conditions on the overall device cooling performance. We present a detailed 3D electrothermal analysis of heat and current distribution in a Bi/sub 2/Te/sub 3/ single-leg element with 50/spl times/50 /spl mu/m/sup 2/ cold side contact area, which is smaller than the element cross section (410/spl times/410 /spl mu/m/sup 2/). We compared the cases when a uniform voltage is applied at the contact and when a uniform current density is applied. The finite element calculation results demonstrate that in the latter case the 3D single-leg element has a very non-uniform temperature distribution at the contact area. Maximum cooling in the center region is 92/spl deg/C, which is 20% higher than the 1D limit (76/spl deg/C) for a typical Bi/sub 2/Te/sub 3/ material with ZT/spl sim/1. Calculations show that it is possible to take away 600 W/cm/sup 2/ at the center 20/spl times/20 /spl mu/m/sup 2/ region, which is 6 times better than the 1D device with the same thickness. In contrast, with a boundary condition of uniform voltage at the cold side contact area, the temperature distribution is as uniform as 1D device and reaches the same maximum cooling temperature as 1D. We also propose the possibility of using array contact structures to achieve the uniform current boundary condition that can improve the maximum device cooling performance. These findings add contact geometry as another degree of freedom to engineer the performance of single and multi stage TE devices.
{"title":"Improved maximum cooling by optimizing the geometry of thermoelectric leg elements","authors":"Yan Zhang, Z. Bian, A. Shakouri","doi":"10.1109/ICT.2005.1519930","DOIUrl":"https://doi.org/10.1109/ICT.2005.1519930","url":null,"abstract":"In this paper, we investigate the effect of the thermoelectric leg geometry and boundary conditions on the overall device cooling performance. We present a detailed 3D electrothermal analysis of heat and current distribution in a Bi/sub 2/Te/sub 3/ single-leg element with 50/spl times/50 /spl mu/m/sup 2/ cold side contact area, which is smaller than the element cross section (410/spl times/410 /spl mu/m/sup 2/). We compared the cases when a uniform voltage is applied at the contact and when a uniform current density is applied. The finite element calculation results demonstrate that in the latter case the 3D single-leg element has a very non-uniform temperature distribution at the contact area. Maximum cooling in the center region is 92/spl deg/C, which is 20% higher than the 1D limit (76/spl deg/C) for a typical Bi/sub 2/Te/sub 3/ material with ZT/spl sim/1. Calculations show that it is possible to take away 600 W/cm/sup 2/ at the center 20/spl times/20 /spl mu/m/sup 2/ region, which is 6 times better than the 1D device with the same thickness. In contrast, with a boundary condition of uniform voltage at the cold side contact area, the temperature distribution is as uniform as 1D device and reaches the same maximum cooling temperature as 1D. We also propose the possibility of using array contact structures to achieve the uniform current boundary condition that can improve the maximum device cooling performance. These findings add contact geometry as another degree of freedom to engineer the performance of single and multi stage TE devices.","PeriodicalId":422400,"journal":{"name":"ICT 2005. 24th International Conference on Thermoelectrics, 2005.","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117207172","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}
Pub Date : 2005-06-19DOI: 10.1109/ICT.2005.1519981
P. Rogl
The present paper focuses on a systematic study of clathrate formation, clathrate structures and bonding in clathrate materials. The analysis shows the difficulties in preparation and design of clathrate compounds at a given electron/atom concentration. Validity and shortcomings of the Zintl concept for clathrates will be outlined. Nevertheless the information obtained, although not complete for many systems, may provide useful in defining compositional regions of interest for further search for novel clathrate materials with interesting thermoelectric properties.
{"title":"Formation of clathrates","authors":"P. Rogl","doi":"10.1109/ICT.2005.1519981","DOIUrl":"https://doi.org/10.1109/ICT.2005.1519981","url":null,"abstract":"The present paper focuses on a systematic study of clathrate formation, clathrate structures and bonding in clathrate materials. The analysis shows the difficulties in preparation and design of clathrate compounds at a given electron/atom concentration. Validity and shortcomings of the Zintl concept for clathrates will be outlined. Nevertheless the information obtained, although not complete for many systems, may provide useful in defining compositional regions of interest for further search for novel clathrate materials with interesting thermoelectric properties.","PeriodicalId":422400,"journal":{"name":"ICT 2005. 24th International Conference on Thermoelectrics, 2005.","volume":"62 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121120782","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}
Pub Date : 2005-06-19DOI: 10.1109/ICT.2005.1519948
A. Assoud, S. Derakhshan, N. Soheilnia, H. Kleinke
We have recently commenced to investigate mixed valent tin chalcogenides as well as polychalcogenides, namely SrSn/sub 2/Se/sub 4/, Sr/sub 2/SnSe/sub 5/, Ba/sub 2/SnSe/sub 5/, and Ba/sub 2/SnTe/sub 5/. These materials exhibit (calculated and in part experimentally confirmed) band gaps between 0.2 eV (Ba/sub 2/SnTe/sub 5/) and 1.2 eV (Ba/sub 2/SnSe/sub 5/). Molecular units are predominant in these materials, namely SnSe/sub 4//sup 4-/ tetrahedra, Sn/sub 3/Se/sub 10//sup 8-/ and Sn/sub 3/Te/sub 10//sup 8u/ilding blocks, respectively, as well as Se/sub 3//sup 2-/ and Te/sub 5//sup 4-/ units. Three-dimensionally interconnected covalent networks were found in the new quaternaries Ba/sub 3/Cu/sub 2/Sn/sub 3/Se/sub 10/, BaCu/sub 2/SnSe/sub 4/, and BaAg/sub 2/SnSe/sub 4/, including the Ba/sup 2+/ cations in one-dimensional channels. Despite the small band gaps (e.g., 0.2 eV for BaAg/sub 2/SnSe/sub 4/), the as-prepared samples exhibit rather small electrical conductivities, but large Seebeck coefficients (above +500 /spl mu/V/K at 300 K). Our most recently discovered polytellurides Ba/sub 3/Cu/sub 14-/spl delta//Te/sub 12/ and Ba/sub 2/Cu/sub 4-/spl delta//Te/sub 5/ comprising extended Cu atom substructures appear to have thermoelectric properties superior to the tin chalcogenides.
{"title":"Exploratory synthesis of new heavy main group chalcogenides","authors":"A. Assoud, S. Derakhshan, N. Soheilnia, H. Kleinke","doi":"10.1109/ICT.2005.1519948","DOIUrl":"https://doi.org/10.1109/ICT.2005.1519948","url":null,"abstract":"We have recently commenced to investigate mixed valent tin chalcogenides as well as polychalcogenides, namely SrSn/sub 2/Se/sub 4/, Sr/sub 2/SnSe/sub 5/, Ba/sub 2/SnSe/sub 5/, and Ba/sub 2/SnTe/sub 5/. These materials exhibit (calculated and in part experimentally confirmed) band gaps between 0.2 eV (Ba/sub 2/SnTe/sub 5/) and 1.2 eV (Ba/sub 2/SnSe/sub 5/). Molecular units are predominant in these materials, namely SnSe/sub 4//sup 4-/ tetrahedra, Sn/sub 3/Se/sub 10//sup 8-/ and Sn/sub 3/Te/sub 10//sup 8u/ilding blocks, respectively, as well as Se/sub 3//sup 2-/ and Te/sub 5//sup 4-/ units. Three-dimensionally interconnected covalent networks were found in the new quaternaries Ba/sub 3/Cu/sub 2/Sn/sub 3/Se/sub 10/, BaCu/sub 2/SnSe/sub 4/, and BaAg/sub 2/SnSe/sub 4/, including the Ba/sup 2+/ cations in one-dimensional channels. Despite the small band gaps (e.g., 0.2 eV for BaAg/sub 2/SnSe/sub 4/), the as-prepared samples exhibit rather small electrical conductivities, but large Seebeck coefficients (above +500 /spl mu/V/K at 300 K). Our most recently discovered polytellurides Ba/sub 3/Cu/sub 14-/spl delta//Te/sub 12/ and Ba/sub 2/Cu/sub 4-/spl delta//Te/sub 5/ comprising extended Cu atom substructures appear to have thermoelectric properties superior to the tin chalcogenides.","PeriodicalId":422400,"journal":{"name":"ICT 2005. 24th International Conference on Thermoelectrics, 2005.","volume":"47 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121385165","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}
Pub Date : 2005-06-19DOI: 10.1109/ICT.2005.1519911
J. Yang
Several proposed applications of thermoelectric (TE) waste heat recovery devices in the automotive industry are reviewed. To assess the feasibility of these applications at a vehicle level, the effect of electrical load and weight on fuel economy for a series of cars and trucks was investigated. These results will help us to identify the appropriate vehicle platforms for TE waste heat recovery, and to establish a set of requirements for an automotive TE waste heat recovery subsystem. The key to the realization of this technology is still the continued development of new materials with increased TE efficiency.
{"title":"Potential applications of thermoelectric waste heat recovery in the automotive industry","authors":"J. Yang","doi":"10.1109/ICT.2005.1519911","DOIUrl":"https://doi.org/10.1109/ICT.2005.1519911","url":null,"abstract":"Several proposed applications of thermoelectric (TE) waste heat recovery devices in the automotive industry are reviewed. To assess the feasibility of these applications at a vehicle level, the effect of electrical load and weight on fuel economy for a series of cars and trucks was investigated. These results will help us to identify the appropriate vehicle platforms for TE waste heat recovery, and to establish a set of requirements for an automotive TE waste heat recovery subsystem. The key to the realization of this technology is still the continued development of new materials with increased TE efficiency.","PeriodicalId":422400,"journal":{"name":"ICT 2005. 24th International Conference on Thermoelectrics, 2005.","volume":"101 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115734310","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}
Pub Date : 2005-06-19DOI: 10.1109/ICT.2005.1519966
K. Gofryk, D. Kaczorowski, A. Jasper, Y. Grin
Four series of ternary compounds REPdSb (RE = Y, Ho, Er), REPdBi (RE = Nd, Y, Dy, Ho, Er), REPd/sub 2/Sb (RE = Y, Gd-Er) and REPd/sub 2/Bi (RE = Y, Dy-Er) were studied by means of magnetization, magnetic susceptibility, electrical resistivity, and thermoelectric power measurements performed in the temperature range 1.7-300 K and in magnetic fields up to 5 T. Magnetic susceptibility measurements of the Heusler phases REPdZ and REPd/sub 2/Z (RE = Y, Gd-Er; Z = Sb, Bi) have revealed that at low temperatures the compounds studied are either paramagnetic or antiferromagnetic with the Neel points of several Kelvin. For all these compounds but Y-based alloys experimental values of the effective magnetic moment are close to the theoretical ones for respective RE/sup 3+/ ions. Electrical resistivity measurements of the half-Heusler phases REPdX (X = Sb, Bi) have indicated their half-metallic or semimetallic character. At low temperatures the resistivity exhibits a metallic-like behaviour, which is probably due to an impurity band possibly overlapping with the conduction band. At high temperatures the electrical conductivities follow the activation law that accounts for gradual thermal depopulation of impurity levels. The positive sign of the Seebeck coefficient could indicate that holes arising from some acceptor centres are dominant carriers. The energy gaps near the Fermi level are of the order of tens millielectron volts and thus are much smaller than values estimated from the electronic structure calculations made for similar compounds. The Seebeck coefficient is quite large, of the order expected for low carrier density semimetals. The thermoelectric figure of merit evaluated for ErPdSb is ZT /spl ap/ 0.15 at room temperature. While half-Heusler alloys have been characterised as narrow-gap semiconductors all the REPd/sub 2/Sb and REPd/sub 2/Bi ternaries have been found to exhibit metallic-like conductivity. For the REPd/sub 2/Bi series a structural transformation from cubic to lower symmetry structures occurs that manifests itself as distinct anomalies in the transport characteristics. The thermoelectric power for these materials is much lower than that of the REPdX alloys.
四大系列的三元化合物REPdSb (Er) = Y, Ho, REPdBi (RE = Nd, Y, Dy, Ho Er), REPd /子2 /某人(= Y, Gd-Er)和REPd /子2 / Bi (= Y, Dy-Er)研究了磁化,磁化率、电阻率、热电动力测量温度范围中执行1.7 -300 K和5 t的磁场磁化率测量的赫斯勒阶段REPdZ和REPd /子2 / Z (RE = Y, Gd-Er;Z = Sb, Bi)表明，在低温下，所研究的化合物要么是顺磁性的，要么是反铁磁性的，具有几个开尔文的尼尔点。除基合金外，所有化合物的有效磁矩的实验值都接近于各自稀土/sup 3+/离子的理论值。对半heusler相REPdX (X = Sb, Bi)的电阻率测量表明其半金属或半金属性质。在低温下，电阻率表现出类似金属的行为，这可能是由于杂质带可能与导带重叠。在高温下，电导率遵循激活定律，该定律解释了杂质水平的逐渐热减少。塞贝克系数的正号可能表明某些受体中心产生的空穴是主要载流子。费米能级附近的能隙约为几十毫电子伏特，因此比类似化合物的电子结构计算估计的值要小得多。塞贝克系数相当大，与低载流子密度半金属的量级相当。在室温下，ErPdSb的热电优值为ZT /spl / 0.15。当半赫斯勒合金被表征为窄间隙半导体时，所有的REPd/sub 2/Sb和REPd/sub 2/Bi三元体都被发现具有类似金属的导电性。对于REPd/ sub2 /Bi系列，发生了从立方结构到低对称结构的结构转换，表现为输运特征的明显异常。这些材料的热电功率远低于REPdX合金。
{"title":"Physical properties of rare-earth-based Heusler phases REPdZ and REPd/sub 2/Z (Z = Sb,Bi)","authors":"K. Gofryk, D. Kaczorowski, A. Jasper, Y. Grin","doi":"10.1109/ICT.2005.1519966","DOIUrl":"https://doi.org/10.1109/ICT.2005.1519966","url":null,"abstract":"Four series of ternary compounds REPdSb (RE = Y, Ho, Er), REPdBi (RE = Nd, Y, Dy, Ho, Er), REPd/sub 2/Sb (RE = Y, Gd-Er) and REPd/sub 2/Bi (RE = Y, Dy-Er) were studied by means of magnetization, magnetic susceptibility, electrical resistivity, and thermoelectric power measurements performed in the temperature range 1.7-300 K and in magnetic fields up to 5 T. Magnetic susceptibility measurements of the Heusler phases REPdZ and REPd/sub 2/Z (RE = Y, Gd-Er; Z = Sb, Bi) have revealed that at low temperatures the compounds studied are either paramagnetic or antiferromagnetic with the Neel points of several Kelvin. For all these compounds but Y-based alloys experimental values of the effective magnetic moment are close to the theoretical ones for respective RE/sup 3+/ ions. Electrical resistivity measurements of the half-Heusler phases REPdX (X = Sb, Bi) have indicated their half-metallic or semimetallic character. At low temperatures the resistivity exhibits a metallic-like behaviour, which is probably due to an impurity band possibly overlapping with the conduction band. At high temperatures the electrical conductivities follow the activation law that accounts for gradual thermal depopulation of impurity levels. The positive sign of the Seebeck coefficient could indicate that holes arising from some acceptor centres are dominant carriers. The energy gaps near the Fermi level are of the order of tens millielectron volts and thus are much smaller than values estimated from the electronic structure calculations made for similar compounds. The Seebeck coefficient is quite large, of the order expected for low carrier density semimetals. The thermoelectric figure of merit evaluated for ErPdSb is ZT /spl ap/ 0.15 at room temperature. While half-Heusler alloys have been characterised as narrow-gap semiconductors all the REPd/sub 2/Sb and REPd/sub 2/Bi ternaries have been found to exhibit metallic-like conductivity. For the REPd/sub 2/Bi series a structural transformation from cubic to lower symmetry structures occurs that manifests itself as distinct anomalies in the transport characteristics. The thermoelectric power for these materials is much lower than that of the REPdX alloys.","PeriodicalId":422400,"journal":{"name":"ICT 2005. 24th International Conference on Thermoelectrics, 2005.","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126414970","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}
Pub Date : 2005-06-19DOI: 10.1109/ICT.2005.1519992
G. Zeng, J. Bowers, Yan Zhang, A. Shakouri, J. Zide, A. Gossard, Woochul Kim, A. Majumdar
InGaAs with embedded ErAs nano-particles is a promising material for thermoelectric applications. The incorporation of erbium arsenide metallic nanoparticles into the semiconductor can provide both charge carriers and create scattering centers for phonons. Electron filtering by heterostructure barriers can also enhance Seebeck coefficient by selective emission of hot electrons. 2.1 /spl mu/m-thick ErAs/InGaAs superlattices with a period of 10 nm InAlGaAs and 20 nm InGaAs were grown using molecular beam epitaxy, and the effective doping is from 2/spl times/10/sup 18/ to 1/spl times/10/sup 19/ cm/sup -3/. Special device patterns were developed for the measurement of the cross-plane Seebeck coefficient of the superlattice layers. Using these device patterns, the combined Seebeck coefficient of superlattice and the substrate were measured and the temperature drops through the superlattice and InP substrate were determined with 3D ANSYS/spl reg/ simulations. The Seebeck coefficient of the superlattice layers is obtained based on the measurements and simulation results.
{"title":"ErAs/InGaAs superlattice Seebeck coefficient","authors":"G. Zeng, J. Bowers, Yan Zhang, A. Shakouri, J. Zide, A. Gossard, Woochul Kim, A. Majumdar","doi":"10.1109/ICT.2005.1519992","DOIUrl":"https://doi.org/10.1109/ICT.2005.1519992","url":null,"abstract":"InGaAs with embedded ErAs nano-particles is a promising material for thermoelectric applications. The incorporation of erbium arsenide metallic nanoparticles into the semiconductor can provide both charge carriers and create scattering centers for phonons. Electron filtering by heterostructure barriers can also enhance Seebeck coefficient by selective emission of hot electrons. 2.1 /spl mu/m-thick ErAs/InGaAs superlattices with a period of 10 nm InAlGaAs and 20 nm InGaAs were grown using molecular beam epitaxy, and the effective doping is from 2/spl times/10/sup 18/ to 1/spl times/10/sup 19/ cm/sup -3/. Special device patterns were developed for the measurement of the cross-plane Seebeck coefficient of the superlattice layers. Using these device patterns, the combined Seebeck coefficient of superlattice and the substrate were measured and the temperature drops through the superlattice and InP substrate were determined with 3D ANSYS/spl reg/ simulations. The Seebeck coefficient of the superlattice layers is obtained based on the measurements and simulation results.","PeriodicalId":422400,"journal":{"name":"ICT 2005. 24th International Conference on Thermoelectrics, 2005.","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131534170","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}
Pub Date : 2005-06-19DOI: 10.1109/ICT.2005.1519892
A. Downey, T. Hogan
Measurements of assembled thermoelectric modules commonly include investigations of the module output power versus load resistance. Such measurements include non-ideal effects such as electrical and thermal contact resistances. Using an AC electrical measurement, a model for a thermoelectric module has been developed utilizing electrical circuits for both the thermal and electrical characteristics of the module. Measurements were taken over the frequency range of 1mHz to 500Hz using lock-in amplifiers. We present data showing the extraction of ZT from such measurements on commercially available modules. By knowing either the heat capacity of the module or the average module Seebeck coefficient, determination of the thermal conductance can also be achieved. The model proposed here provides a simple equivalent circuit which can be analyzed using an electrical simulator such as SPICE. This model makes use of the magnitude and phase of the electrical impedance measured by the lock-in amplifiers at the input terminals of the module and includes fitting parameters of the total electrical resistance, thermal conductance, heat capacitance, and module Seebeck coefficient.
{"title":"Circuit model of a thermoelectric module for ac electrical measurements","authors":"A. Downey, T. Hogan","doi":"10.1109/ICT.2005.1519892","DOIUrl":"https://doi.org/10.1109/ICT.2005.1519892","url":null,"abstract":"Measurements of assembled thermoelectric modules commonly include investigations of the module output power versus load resistance. Such measurements include non-ideal effects such as electrical and thermal contact resistances. Using an AC electrical measurement, a model for a thermoelectric module has been developed utilizing electrical circuits for both the thermal and electrical characteristics of the module. Measurements were taken over the frequency range of 1mHz to 500Hz using lock-in amplifiers. We present data showing the extraction of ZT from such measurements on commercially available modules. By knowing either the heat capacity of the module or the average module Seebeck coefficient, determination of the thermal conductance can also be achieved. The model proposed here provides a simple equivalent circuit which can be analyzed using an electrical simulator such as SPICE. This model makes use of the magnitude and phase of the electrical impedance measured by the lock-in amplifiers at the input terminals of the module and includes fitting parameters of the total electrical resistance, thermal conductance, heat capacitance, and module Seebeck coefficient.","PeriodicalId":422400,"journal":{"name":"ICT 2005. 24th International Conference on Thermoelectrics, 2005.","volume":"91 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132593292","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}
Filled skutterudite compounds (Ce,La)/sub y/FeCo/sub 3/Sb/sub 12/ with y=0.1/spl sim/0.3 were synthesized by solid state reaction-spark plasma sintering (SPS) using powders of Co, Sb, Fe and rare earth Ce as starting materials, and the thermoelectric properties of the compounds were also studied. It is shown that there is a little Sb in filled skutterudite compounds (Ce,La)/sub y/FeCo/sub 3/Sb/sub 12/ with y=0.1/spl sim/0.3 at 900 K. The lattice constant and the Seebeck coefficient of the compounds increases with the filling fraction of the Ce and La, while the thermal conductivity and electrical conductivity is greatly reduced The compounds had a minimum value of thermal conductivity with y=0.3, indicating that it is the coupling rattling and the irregular distribution between the two filler ions of La and Ce that give rise to the mass change of atom and the additional phonon scattering produced by lattice aberration when the Sb voids in the skutterudite structure were filled by Ce and La. The compound of Ce/sub 0.1/La/sub 0.2/Fe/sub 1.0/Co/sub 3.0/Sb/sub 12/ with Co-rich had a maximum value of the dimensionless figure of merit ZT=0.46 at 773 K.
{"title":"The thermoelectric properties of (Ce,La)/sub y/Fe/sub 1.0/Co/sub 3.0/Sb/sub 12/ compounds by solid state reaction and spark plasma sintering","authors":"J.X. Zhang, Q. Lu, X. Zhang, Y.Q. Liu, D. Liu, M.L. Zhou","doi":"10.1109/ICT.2005.1519909","DOIUrl":"https://doi.org/10.1109/ICT.2005.1519909","url":null,"abstract":"Filled skutterudite compounds (Ce,La)/sub y/FeCo/sub 3/Sb/sub 12/ with y=0.1/spl sim/0.3 were synthesized by solid state reaction-spark plasma sintering (SPS) using powders of Co, Sb, Fe and rare earth Ce as starting materials, and the thermoelectric properties of the compounds were also studied. It is shown that there is a little Sb in filled skutterudite compounds (Ce,La)/sub y/FeCo/sub 3/Sb/sub 12/ with y=0.1/spl sim/0.3 at 900 K. The lattice constant and the Seebeck coefficient of the compounds increases with the filling fraction of the Ce and La, while the thermal conductivity and electrical conductivity is greatly reduced The compounds had a minimum value of thermal conductivity with y=0.3, indicating that it is the coupling rattling and the irregular distribution between the two filler ions of La and Ce that give rise to the mass change of atom and the additional phonon scattering produced by lattice aberration when the Sb voids in the skutterudite structure were filled by Ce and La. The compound of Ce/sub 0.1/La/sub 0.2/Fe/sub 1.0/Co/sub 3.0/Sb/sub 12/ with Co-rich had a maximum value of the dimensionless figure of merit ZT=0.46 at 773 K.","PeriodicalId":422400,"journal":{"name":"ICT 2005. 24th International Conference on Thermoelectrics, 2005.","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129277746","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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