Pub Date : 2005-06-19DOI: 10.1109/ICT.2005.1519986
A. Levin
A model for thermopile detectors is developed using a MatLab based numerical simulation. The model uses geometry and physical parameters of thermopile materials as input data and calculates the main characteristics of the detector. The numerical results closely agree with experimentally determined parameters. The influence of several input parameters on the detector's performance is studied. Using this approach the output signal of the Dexter Research ST150 detector is improved by 30%. A new model of a CMOS based detector for gas analysis is optimized. The simulation results show significant improvement in the detector's performance when poly-Si/Al materials are substituted by n-poly-Si/p-poly-Si materials. The model predicts D* = 2.5/spl times/10/sup 8/ cmHz/sup 1/2//W with a time constant of 17 ms.
利用MatLab建立了热电堆探测器的数值模拟模型。该模型以热电堆材料的几何和物理参数作为输入数据，计算探测器的主要特性。数值结果与实验参数吻合较好。研究了几种输入参数对探测器性能的影响。采用这种方法，Dexter Research ST150探测器的输出信号提高了30%。对一种新型的CMOS气体分析探测器进行了优化设计。仿真结果表明，用n-多晶硅/p-多晶硅材料替代多晶硅/Al材料后，探测器的性能有了明显改善。该模型预测D* = 2.5/spl倍/10/sup 8/ cmHz/sup 1/2//W，时间常数为17 ms。
{"title":"A numerical simulation tool for infrared thermopile detectors","authors":"A. Levin","doi":"10.1109/ICT.2005.1519986","DOIUrl":"https://doi.org/10.1109/ICT.2005.1519986","url":null,"abstract":"A model for thermopile detectors is developed using a MatLab based numerical simulation. The model uses geometry and physical parameters of thermopile materials as input data and calculates the main characteristics of the detector. The numerical results closely agree with experimentally determined parameters. The influence of several input parameters on the detector's performance is studied. Using this approach the output signal of the Dexter Research ST150 detector is improved by 30%. A new model of a CMOS based detector for gas analysis is optimized. The simulation results show significant improvement in the detector's performance when poly-Si/Al materials are substituted by n-poly-Si/p-poly-Si materials. The model predicts D* = 2.5/spl times/10/sup 8/ cmHz/sup 1/2//W with a time constant of 17 ms.","PeriodicalId":422400,"journal":{"name":"ICT 2005. 24th International Conference on Thermoelectrics, 2005.","volume":"83 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":"121690318","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.2005.1519972
S. Ur, J. Kwon, Il-ho Kim, P. Nash, Young‐Geun Lee, S. Kweon, T. Hong
Powder metallurgy was used to produce polycrystalline specimens of single phase /spl epsi/-Zn/sub 4/Sb/sub 3/ and two-phase specimens of /spl epsi/-Zn/sub 4/Sb/sub 3/ (majority phase) and Zn. The effect of excess Zn addition to the stoichiometry of Zn/sub 4/Sb/sub 3/ was investigated on the thermoelectric properties as well as mechanical properties in the alloy system. The room-temperature thermoelectric properties of our single phase Zn/sub 4/Sb/sub 3/ alloys are comparable to those reported by other researchers on samples prepared by hot pressing of ingot melted alloy powders. It is shown that the addition of Zn enhances the mechanical properties while sacrificing the thermoelectric properties.
{"title":"Effect of Zn addition on thermoelectric properties of Zn/sub 4/Sb/sub 3/ synthesized by direct hot pressing","authors":"S. Ur, J. Kwon, Il-ho Kim, P. Nash, Young‐Geun Lee, S. Kweon, T. Hong","doi":"10.1109/ICT.2005.1519972","DOIUrl":"https://doi.org/10.1109/ICT.2005.1519972","url":null,"abstract":"Powder metallurgy was used to produce polycrystalline specimens of single phase /spl epsi/-Zn/sub 4/Sb/sub 3/ and two-phase specimens of /spl epsi/-Zn/sub 4/Sb/sub 3/ (majority phase) and Zn. The effect of excess Zn addition to the stoichiometry of Zn/sub 4/Sb/sub 3/ was investigated on the thermoelectric properties as well as mechanical properties in the alloy system. The room-temperature thermoelectric properties of our single phase Zn/sub 4/Sb/sub 3/ alloys are comparable to those reported by other researchers on samples prepared by hot pressing of ingot melted alloy powders. It is shown that the addition of Zn enhances the mechanical properties while sacrificing the thermoelectric properties.","PeriodicalId":422400,"journal":{"name":"ICT 2005. 24th International Conference on Thermoelectrics, 2005.","volume":"24 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":"125124918","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.2005.1519927
M. Beekman, J. Gryko, H. F. Rubin, J. Kaduk, W. Wong-Ng, G. Nolas
We present electrical resistivity and thermal conductivity for low alkali content NaSi/sub 36/, and compare it to the "fully loaded" Cs/sub 8/Na/sub 16/Si/sub 136/. Our results show that the electrical resistivities of the high and low alkali content materials differ greatly. Na/sub 1/Si/sub 136/ possesses a low thermal conductivity, similar in magnitude and temperature dependence to that of the "empty" clathrate Si/sub 136/. Extensive attempts at synthesizing Na/sub x/Ge/sub 136/ did not produce the clathrate phase in high enough yield for transport measurements, but instead an initially unidentified Na-Ge phase was prevalent. In order to clarify confusion in the literature, we propose a structural model for this novel phase, with resulting composition Na/sub 1-x/Ge/sub 3/. The potential of type II clathrates for thermoelectric applications is reviewed.
{"title":"Synthesis and transport properties of type II clathrates","authors":"M. Beekman, J. Gryko, H. F. Rubin, J. Kaduk, W. Wong-Ng, G. Nolas","doi":"10.1109/ICT.2005.1519927","DOIUrl":"https://doi.org/10.1109/ICT.2005.1519927","url":null,"abstract":"We present electrical resistivity and thermal conductivity for low alkali content NaSi/sub 36/, and compare it to the \"fully loaded\" Cs/sub 8/Na/sub 16/Si/sub 136/. Our results show that the electrical resistivities of the high and low alkali content materials differ greatly. Na/sub 1/Si/sub 136/ possesses a low thermal conductivity, similar in magnitude and temperature dependence to that of the \"empty\" clathrate Si/sub 136/. Extensive attempts at synthesizing Na/sub x/Ge/sub 136/ did not produce the clathrate phase in high enough yield for transport measurements, but instead an initially unidentified Na-Ge phase was prevalent. In order to clarify confusion in the literature, we propose a structural model for this novel phase, with resulting composition Na/sub 1-x/Ge/sub 3/. The potential of type II clathrates for thermoelectric applications is reviewed.","PeriodicalId":422400,"journal":{"name":"ICT 2005. 24th International Conference on Thermoelectrics, 2005.","volume":"23 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":"124517447","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.2005.1519937
R. Rostek, B. Schmid, C. Mortensen, D.C. Johnson
Superlattices based on the thermoelectric standard compounds Bi/sub 2/Te/sub 3/ and Sb/sub 2/Te/sub 3/ demonstrate enhanced ZT values. The formation of the superlattice (Bi/sub 2/Te/sub 3/)/sub x/(Sb/sub 2/Te/sub 3/)/sub y/ through the modulated elemental reactants (MER) approach is hindered by interdiffusion of the Bi/sub 2/Te/sub 3/ and Sb/sub 2/Te/sub 3/ layers at the necessary annealing temperatures. TiTe/sub 2/ has the potential to act as a diffusion barrier between the Bi/sub 2/Te/sub 3/ and Sb/sub 2/Te/sub 3/ layers of the superlattice. (TiTe/sub 2/)/sub 3/(Bi/sub 2/Te/sub 3/)/sub y/(TiTe/sub 2/)/sub 3/(Sb/sub 2/Te/sub 3/)/sub z/ superlattices were synthesized using the MER approach, successfully separating the different V-VI layers by TiTe/sub 2/. This study shows that the number of Bi/sub 2/Te/sub 3/ and Sb/sub 2/Te/sub 3/ layers can be precisely controlled using the MER method.
{"title":"Progress towards the preparation of (TiTe/sub 2/)/sub 3/(Bi/sub 2/Te/sub 3/)/sub y/(TiTe/sub 2/)/sub 3/(Sb/sub 2/Te/sub 3/)/sub z/ superlattices","authors":"R. Rostek, B. Schmid, C. Mortensen, D.C. Johnson","doi":"10.1109/ICT.2005.1519937","DOIUrl":"https://doi.org/10.1109/ICT.2005.1519937","url":null,"abstract":"Superlattices based on the thermoelectric standard compounds Bi/sub 2/Te/sub 3/ and Sb/sub 2/Te/sub 3/ demonstrate enhanced ZT values. The formation of the superlattice (Bi/sub 2/Te/sub 3/)/sub x/(Sb/sub 2/Te/sub 3/)/sub y/ through the modulated elemental reactants (MER) approach is hindered by interdiffusion of the Bi/sub 2/Te/sub 3/ and Sb/sub 2/Te/sub 3/ layers at the necessary annealing temperatures. TiTe/sub 2/ has the potential to act as a diffusion barrier between the Bi/sub 2/Te/sub 3/ and Sb/sub 2/Te/sub 3/ layers of the superlattice. (TiTe/sub 2/)/sub 3/(Bi/sub 2/Te/sub 3/)/sub y/(TiTe/sub 2/)/sub 3/(Sb/sub 2/Te/sub 3/)/sub z/ superlattices were synthesized using the MER approach, successfully separating the different V-VI layers by TiTe/sub 2/. This study shows that the number of Bi/sub 2/Te/sub 3/ and Sb/sub 2/Te/sub 3/ layers can be precisely controlled using the MER method.","PeriodicalId":422400,"journal":{"name":"ICT 2005. 24th International Conference on Thermoelectrics, 2005.","volume":"1 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":"126213967","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.2005.1519877
M. Jeng, Ronggui Yang, Gang Chen
This paper presents a Monte Carlo simulation scheme to study the thermoelectric properties of nanocomposites with special attention paid to the implementation of periodic boundary condition in Monte Carlo simulation. The scheme is applied to study the thermal conductivity of silicon germanium (Si-Ge) nanocomposites, which are of great interest for high efficiency thermoelectric material development. The size effects of phonon transport in nanoparticle composites were studied and the results show that the thermal conductivity of nanoparticle composites can be lower than alloy value. It was found that randomly distributed nanoparticles in nanocomposites rendered the thermal conductivity values very close to that of nanocomposites with periodically aligned mono-size nanoparticles. This suggests that interfacial area per unit volume is a useful parameter to correlate the size effect of thermoelectric properties in nanocomposites.
{"title":"Monte Carlo simulation of thermoelectric properties in nanocomposites","authors":"M. Jeng, Ronggui Yang, Gang Chen","doi":"10.1109/ICT.2005.1519877","DOIUrl":"https://doi.org/10.1109/ICT.2005.1519877","url":null,"abstract":"This paper presents a Monte Carlo simulation scheme to study the thermoelectric properties of nanocomposites with special attention paid to the implementation of periodic boundary condition in Monte Carlo simulation. The scheme is applied to study the thermal conductivity of silicon germanium (Si-Ge) nanocomposites, which are of great interest for high efficiency thermoelectric material development. The size effects of phonon transport in nanoparticle composites were studied and the results show that the thermal conductivity of nanoparticle composites can be lower than alloy value. It was found that randomly distributed nanoparticles in nanocomposites rendered the thermal conductivity values very close to that of nanocomposites with periodically aligned mono-size nanoparticles. This suggests that interfacial area per unit volume is a useful parameter to correlate the size effect of thermoelectric properties in nanocomposites.","PeriodicalId":422400,"journal":{"name":"ICT 2005. 24th International Conference on Thermoelectrics, 2005.","volume":"78 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":"127719514","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.2005.1519886
Y. Kucherov, P. Hagelstein, V. Sevastyanenko, S. Guruswamy, H. L. Brown, D. Thimmegowda
Experiments on thermal diodes in InSb constructed with a p-type blocking layer in an n*pn structure have shown the existence of an optimum in acceptor concentration and width. Results for various potential barrier shapes show that triangle-shaped barriers outperform barriers with rectangular shape. Enhancements have been demonstrated in PbTe thermal diodes. In InSb and in PbTe diodes, the optimum width is on the order of the scattering length, which is different in the two semiconductors by an order of magnitude.
{"title":"Update on thermal diodes","authors":"Y. Kucherov, P. Hagelstein, V. Sevastyanenko, S. Guruswamy, H. L. Brown, D. Thimmegowda","doi":"10.1109/ICT.2005.1519886","DOIUrl":"https://doi.org/10.1109/ICT.2005.1519886","url":null,"abstract":"Experiments on thermal diodes in InSb constructed with a p-type blocking layer in an n*pn structure have shown the existence of an optimum in acceptor concentration and width. Results for various potential barrier shapes show that triangle-shaped barriers outperform barriers with rectangular shape. Enhancements have been demonstrated in PbTe thermal diodes. In InSb and in PbTe diodes, the optimum width is on the order of the scattering length, which is different in the two semiconductors by an order of magnitude.","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":"126976238","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.2005.1519982
G. Fowler, G. Nolas
There has been substantial effort in investigating the thermal transport in filled skutterudites over the past decade in order to optimize their thermoelectric properties. This effort has resulted in the accumulation of a large amount of experimental data in the literature. We have tapped into this wealth of data and have begun an assessment of the role of the filler atoms, and dopants, on point defect and resonance scattering. We investigate the lattice thermal conductivity of lanthanum-filled skutterudites at different lanthanum concentrations using the Debye model and incorporating boundary, point defect, Umklapp and resonance scattering mechanisms.
{"title":"Assessing the role of the filler atoms on the thermal conductivity of La-filled skutterudites","authors":"G. Fowler, G. Nolas","doi":"10.1109/ICT.2005.1519982","DOIUrl":"https://doi.org/10.1109/ICT.2005.1519982","url":null,"abstract":"There has been substantial effort in investigating the thermal transport in filled skutterudites over the past decade in order to optimize their thermoelectric properties. This effort has resulted in the accumulation of a large amount of experimental data in the literature. We have tapped into this wealth of data and have begun an assessment of the role of the filler atoms, and dopants, on point defect and resonance scattering. We investigate the lattice thermal conductivity of lanthanum-filled skutterudites at different lanthanum concentrations using the Debye model and incorporating boundary, point defect, Umklapp and resonance scattering mechanisms.","PeriodicalId":422400,"journal":{"name":"ICT 2005. 24th International Conference on Thermoelectrics, 2005.","volume":"1 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":"131226245","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.2005.1519921
T. Humphrey, M. O'Dwyer, Ali Shakouri
We show that the expressions for current and heat current calculated via (the non-linearized) ballistic and diffusive transport formalisms reduce to the same form for solid-state devices one electron mean free path in length. The materials parameters for thermionic and thermoelectric devices are also shown to be equal, rather than differing by a multiplicative constant. We derive a simple transport equation that includes both ballistic and diffusive contributions to the current, and, as an example, use this to calculate the maximum temperature difference obtainable for a piece of Bi/sub 2/Te/sub 3/ as a function of its length, from less than an electron mean-free path to much greater than a mean-free path. Finally we briefly discuss similarities and differences between thermionic and thermoelectric devices in the regime where device length is of the order of a mean-free path length.
{"title":"A further comparison of solid-state thermionic and thermoelectric refrigeration","authors":"T. Humphrey, M. O'Dwyer, Ali Shakouri","doi":"10.1109/ICT.2005.1519921","DOIUrl":"https://doi.org/10.1109/ICT.2005.1519921","url":null,"abstract":"We show that the expressions for current and heat current calculated via (the non-linearized) ballistic and diffusive transport formalisms reduce to the same form for solid-state devices one electron mean free path in length. The materials parameters for thermionic and thermoelectric devices are also shown to be equal, rather than differing by a multiplicative constant. We derive a simple transport equation that includes both ballistic and diffusive contributions to the current, and, as an example, use this to calculate the maximum temperature difference obtainable for a piece of Bi/sub 2/Te/sub 3/ as a function of its length, from less than an electron mean-free path to much greater than a mean-free path. Finally we briefly discuss similarities and differences between thermionic and thermoelectric devices in the regime where device length is of the order of a mean-free path length.","PeriodicalId":422400,"journal":{"name":"ICT 2005. 24th International Conference on Thermoelectrics, 2005.","volume":"289 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":"131646067","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.2005.1519943
M. Craps, N. Gothard, R. Rao, J. Gaillard, T. Tritt, A. Rao
Bulk Bi/sub 2/Te/sub 3/ is one of the best known thermoelectric materials with a ZT /spl sim/1 at room temperature. Theoretical studies have suggested that low-dimensional materials may exhibit ZT values that exceed 1. In this study, we used the pulsed laser deposition method to prepare Bi/sub 2/Te/sub 3/ nanostructures by ablating a rotating Bi/sub 2/Te/sub 3/ target in an inert atmosphere. Silicon or quartz substrates are pretreated with poly-1-lysine to form an adhesion layer for 10, 20, and 30 nm colloidal Au particles which serve as catalyst seed particles for the growth of the nanostructures. Alternatively, we have also prepared Bi/sub 2/Te/sub 3/ nanostructures by subliming Bi/sub 2/Te/sub 3/ powder in the presence of gold coated substrates. Results from electron microscopy and vibrational spectroscopic studies are presented.
{"title":"Growth and characterization of Bi/sub 2/Te/sub 3/ nanostructures","authors":"M. Craps, N. Gothard, R. Rao, J. Gaillard, T. Tritt, A. Rao","doi":"10.1109/ICT.2005.1519943","DOIUrl":"https://doi.org/10.1109/ICT.2005.1519943","url":null,"abstract":"Bulk Bi/sub 2/Te/sub 3/ is one of the best known thermoelectric materials with a ZT /spl sim/1 at room temperature. Theoretical studies have suggested that low-dimensional materials may exhibit ZT values that exceed 1. In this study, we used the pulsed laser deposition method to prepare Bi/sub 2/Te/sub 3/ nanostructures by ablating a rotating Bi/sub 2/Te/sub 3/ target in an inert atmosphere. Silicon or quartz substrates are pretreated with poly-1-lysine to form an adhesion layer for 10, 20, and 30 nm colloidal Au particles which serve as catalyst seed particles for the growth of the nanostructures. Alternatively, we have also prepared Bi/sub 2/Te/sub 3/ nanostructures by subliming Bi/sub 2/Te/sub 3/ powder in the presence of gold coated substrates. Results from electron microscopy and vibrational spectroscopic studies are presented.","PeriodicalId":422400,"journal":{"name":"ICT 2005. 24th International Conference on Thermoelectrics, 2005.","volume":"60 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":"116985600","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.2005.1519931
Wilfried Wunderlich, S. Ohta, Hiromichi Ohta, K. Koumoto
The Ruddlesden-Popper phase (SrTiO/sub 3/)/sub n/(SrO)/sub m/ with n=2, m=1 is considered as an advanced thermoelectric layered material based on ceramic semiconductors and combines the high electric conductivity of SrTiO/sub 3/ with the low thermal conductivity of SrO due to the concept of nanoblock integration. However, it still need to be improved: in SrTiO/sub 3/ the effective mass as one of main factors for the Seebeck coefficient can be enlarged through substitution by heavy elements as calculated from the curvature of the electronic band structure. The effective mass increases with the substitution of Ba on the A-site and V on the B-site in SrTiO/sub 3/. For the RP-phases STO327, STO214 it shows anisotropy of more than a factor of two for in-plane and out-of-plane-directions and the Sr-O and Ti-O bonds show a stronger localization at the SrO/SrTiO/sub 3/ interface than in SrTiO/sub 3/-bulk, but the average effective mass is rather low.
{"title":"Effective mass and thermoelectric properties of SrTiO/sub 3/-based natural superlattices evaluated by ab-initio calculations","authors":"Wilfried Wunderlich, S. Ohta, Hiromichi Ohta, K. Koumoto","doi":"10.1109/ICT.2005.1519931","DOIUrl":"https://doi.org/10.1109/ICT.2005.1519931","url":null,"abstract":"The Ruddlesden-Popper phase (SrTiO/sub 3/)/sub n/(SrO)/sub m/ with n=2, m=1 is considered as an advanced thermoelectric layered material based on ceramic semiconductors and combines the high electric conductivity of SrTiO/sub 3/ with the low thermal conductivity of SrO due to the concept of nanoblock integration. However, it still need to be improved: in SrTiO/sub 3/ the effective mass as one of main factors for the Seebeck coefficient can be enlarged through substitution by heavy elements as calculated from the curvature of the electronic band structure. The effective mass increases with the substitution of Ba on the A-site and V on the B-site in SrTiO/sub 3/. For the RP-phases STO327, STO214 it shows anisotropy of more than a factor of two for in-plane and out-of-plane-directions and the Sr-O and Ti-O bonds show a stronger localization at the SrO/SrTiO/sub 3/ interface than in SrTiO/sub 3/-bulk, but the average effective mass is rather low.","PeriodicalId":422400,"journal":{"name":"ICT 2005. 24th International Conference on Thermoelectrics, 2005.","volume":"1 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":"126053869","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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