The Experts below are selected from a list of 26238 Experts worldwide ranked by ideXlab platform
Xin Bing Zhao - One of the best experts on this subject based on the ideXlab platform.
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unique role of refractory ta alloying in enhancing the figure of merit of nbfesb Thermoelectric Materials
2018Co-Authors: Yintu Liu, Xin Bing Zhao, Umut Aydemir, Jeffrey G Snyder, Kaiyang Xia, Thomas C Chasapis, Tie-jun ZhuAbstract:NbFeSb-based half-Heusler alloys have been recently identified as promising high-temperature Thermoelectric Materials with a figure of merit zT > 1, but their thermal conductivity is still relatively high. Alloying Ta at the Nb site would be highly desirable because the large mass fluctuation between them could effectively scatter phonons and reduce the lattice thermal conductivity. However, practically it is a great challenge due to the high melting point of refractory Ta. Here, the successful synthesis of Ta-alloyed (Nb1−xTax)0.8Ti0.2FeSb (x = 0 – 0.4) solid solutions with significantly reduced thermal conductivity by levitation melting is reported. Because of the similar atomic sizes and chemistry of Nb and Ta, the solid solutions exhibit almost unaltered electrical properties. As a result, an overall zT enhancement from 300 to 1200 K is realized in the single-phase Ta-alloyed solid solutions, and the compounds with x = 0.36 and 0.4 reach a maximum zT of 1.6 at 1200 K. This work also highlights that the isoelectronic substitution by atoms with similar size and chemical nature but large mass difference should reduce the lattice thermal conductivity but maintain good electrical properties in Thermoelectric Materials, which can be a guide for optimizing the figure of merit by alloying.
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New Insights into Intrinsic Point Defects in V2VI3 Thermoelectric Materials
2016Co-Authors: Lipeng Hu, Xin Bing Zhao, Jian HeAbstract:Defects and defect engineering are at the core of many regimes of material research, including the field of Thermoelectric study. The 60-year history of V2VI3 Thermoelectric Materials is a prime example of how a class of semiconductor material, considered mature several times, can be rejuvenated by better understanding and manipulation of defects. This review aims to provide a systematic account of the underexplored intrinsic point defects in V2VI3 compounds, with regard to (i) their formation and control, and (ii) their interplay with other types of defects towards higher Thermoelectric performance. We herein present a convincing case that intrinsic point defects can be actively controlled by extrinsic doping and also via compositional, mechanical, and thermal control at various stages of material synthesis. An up-to-date understanding of intrinsic point defects in V2VI3 compounds is summarized in a (χ, r)-model and applied to elucidating the donor-like effect. These new insights not only enable more innovative defect engineering in other Thermoelectric Materials but also, in a broad context, contribute to rational defect design in advanced functional Materials at large.
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realizing high figure of merit in heavy band p type half heusler Thermoelectric Materials
2015Co-Authors: Shengqiang Bai, Xin Bing Zhao, Yintu Liu, Lidong Chen, Yunshan Tang, Tie-jun ZhuAbstract:Thermoelectric Materials could be used to convert waste heat into useful electricity, but the ideal substance needs to both optimize the electrical power factor and suppress thermal conductivity. Here, the authors report a high figure of merit of 1.5 at 1,200 K in the p-type half-Heusler alloy FeNbSb.
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High Efficiency Half-Heusler Thermoelectric Materials for Energy Harvesting
2015Co-Authors: Tie-jun Zhu, Han Hui Xie, Yintu Liu, Chen Guang Fu, Xin Bing ZhaoAbstract:Half-Heusler (HH) compounds have gained ever-increasing popularity as promising high temperature Thermoelectric Materials. High figure of merit zT of ≈1.0 above 1000 K has recently been realized for both n-type and p-type HH compounds, demonstrating the realistic prospect of these high temperature compounds for high efficiency power generation. Here, recent progress in advanced fabrication techniques and the intrinsic atomic disorders in HH compounds, which are linked to the understanding of the electrical transport, is discussed. Thermoelectric transport features of n-type ZrNiSn-based HH alloys are particularly emphasized, which is beneficial to further improving Thermoelectric performance and comprehensively understanding the underlying mechanisms in HH Thermoelectric Materials. The rational design and realization of new high performance p-type Fe(V,Nb)Sb-based HH compounds are also demonstrated. The outlook for future research directions of HH Thermoelectric Materials is also discussed.
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point defect engineering of high performance bismuth telluride based Thermoelectric Materials
2014Co-Authors: Lipeng Hu, Xin Bing ZhaoAbstract:Developing high-performance Thermoelectric Materials is one of the crucial aspects for direct thermal-to-electric energy conversion. Herein, atomic scale point defect engineering is introduced as a new strategy to simultaneously optimize the electrical properties and lattice thermal conductivity of Thermoelectric Materials, and (Bi,Sb)2(Te,Se)3 Thermoelectric solid solutions are selected as a paradigm to demonstrate the applicability of this new approach. Intrinsic point defects play an important role in enhancing the Thermoelectric properties. Antisite defects and donor-like effects are engineered in this system by tuning the formation energy of point defects and hot deformation. As a result, a record value of the figure of merit ZT of ≈1.2 at 445 K is obtained for n-type polycrystalline Bi2Te2.3Se0.7 alloys, and a high ZT value of ≈1.3 at 380 K is achieved for p-type polycrystalline Bi0.3Sb1.7Te3 alloys, both values being higher than those of commercial zone-melted ingots. These results demonstrate the promise of point defect engineering as a new strategy to optimize Thermoelectric properties.
Tie-jun Zhu - One of the best experts on this subject based on the ideXlab platform.
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unique role of refractory ta alloying in enhancing the figure of merit of nbfesb Thermoelectric Materials
2018Co-Authors: Yintu Liu, Xin Bing Zhao, Umut Aydemir, Jeffrey G Snyder, Kaiyang Xia, Thomas C Chasapis, Tie-jun ZhuAbstract:NbFeSb-based half-Heusler alloys have been recently identified as promising high-temperature Thermoelectric Materials with a figure of merit zT > 1, but their thermal conductivity is still relatively high. Alloying Ta at the Nb site would be highly desirable because the large mass fluctuation between them could effectively scatter phonons and reduce the lattice thermal conductivity. However, practically it is a great challenge due to the high melting point of refractory Ta. Here, the successful synthesis of Ta-alloyed (Nb1−xTax)0.8Ti0.2FeSb (x = 0 – 0.4) solid solutions with significantly reduced thermal conductivity by levitation melting is reported. Because of the similar atomic sizes and chemistry of Nb and Ta, the solid solutions exhibit almost unaltered electrical properties. As a result, an overall zT enhancement from 300 to 1200 K is realized in the single-phase Ta-alloyed solid solutions, and the compounds with x = 0.36 and 0.4 reach a maximum zT of 1.6 at 1200 K. This work also highlights that the isoelectronic substitution by atoms with similar size and chemical nature but large mass difference should reduce the lattice thermal conductivity but maintain good electrical properties in Thermoelectric Materials, which can be a guide for optimizing the figure of merit by alloying.
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realizing high figure of merit in heavy band p type half heusler Thermoelectric Materials
2015Co-Authors: Shengqiang Bai, Xin Bing Zhao, Yintu Liu, Lidong Chen, Yunshan Tang, Tie-jun ZhuAbstract:Thermoelectric Materials could be used to convert waste heat into useful electricity, but the ideal substance needs to both optimize the electrical power factor and suppress thermal conductivity. Here, the authors report a high figure of merit of 1.5 at 1,200 K in the p-type half-Heusler alloy FeNbSb.
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High Efficiency Half-Heusler Thermoelectric Materials for Energy Harvesting
2015Co-Authors: Tie-jun Zhu, Han Hui Xie, Yintu Liu, Chen Guang Fu, Xin Bing ZhaoAbstract:Half-Heusler (HH) compounds have gained ever-increasing popularity as promising high temperature Thermoelectric Materials. High figure of merit zT of ≈1.0 above 1000 K has recently been realized for both n-type and p-type HH compounds, demonstrating the realistic prospect of these high temperature compounds for high efficiency power generation. Here, recent progress in advanced fabrication techniques and the intrinsic atomic disorders in HH compounds, which are linked to the understanding of the electrical transport, is discussed. Thermoelectric transport features of n-type ZrNiSn-based HH alloys are particularly emphasized, which is beneficial to further improving Thermoelectric performance and comprehensively understanding the underlying mechanisms in HH Thermoelectric Materials. The rational design and realization of new high performance p-type Fe(V,Nb)Sb-based HH compounds are also demonstrated. The outlook for future research directions of HH Thermoelectric Materials is also discussed.
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Beneficial contribution of alloy disorder to electron and phonon transport in half-heusler Thermoelectric Materials
2013Co-Authors: Han Hui Xie, Xin Bing Zhao, Chen Guang Fu, Yanzhong Pei, G. Jeffrey Snyder, Heng Wang, Xiaohua Liu, Tie-jun ZhuAbstract:Electron and phonon transport characteristics determines the potential of Thermoelectric Materials for power generation or refrigeration. This work shows that, different from most of high performance Thermoelectric Materials with dominant acoustic phonon scattering, the promising ZrNiSn based half-Heusler Thermoelectric solid solutions exhibit an alloy scattering dominated charge transport. A low deformation potential and a low alloy scattering potential are found for the solid solutions, which is beneficial to maintain a relatively high electron mobility despite of the large effective mass, and can be intrinsic favorable features contributing to the noticeably high power factors of ZrNiSn based alloys. A quantitive description of the different phonon scattering mechanisms suggests that the point defect scattering is the most important mechanism that determines the phonon transport process of the solid solutions. The present results indicate that alloying can be an effective approach for such Materials systems to enhance Thermoelectric figure of merit ZT by reducing phonon thermal conductivity, while minimizing the deterioration of charge mobility due to the low alloy scatteirng potential.
Mercouri G Kanatzidis - One of the best experts on this subject based on the ideXlab platform.
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Rationally Designing High-Performance Bulk Thermoelectric Materials
2016Co-Authors: Gangjian Tan, Li-dong Zhao, Mercouri G KanatzidisAbstract:There has been a renaissance of interest in exploring highly efficient Thermoelectric Materials as a possible route to address the worldwide energy generation, utilization, and management. This review describes the recent advances in designing high-performance bulk Thermoelectric Materials. We begin with the fundamental stratagem of achieving the greatest Thermoelectric figure of merit ZT of a given material by carrier concentration engineering, including Fermi level regulation and optimum carrier density stabilization. We proceed to discuss ways of maximizing ZT at a constant doping level, such as increase of band degeneracy (crystal structure symmetry, band convergence), enhancement of band effective mass (resonant levels, band flattening), improvement of carrier mobility (modulation doping, texturing), and decrease of lattice thermal conductivity (synergistic alloying, second-phase nanostructuring, mesostructuring, and all-length-scale hierarchical architectures). We then highlight the decoupling of th...
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high performance na doped pbte pbs Thermoelectric Materials electronic density of states modification and shape controlled nanostructures
2011Co-Authors: Steven N Girard, Ctirad Uher, Mercouri G Kanatzidis, Xiaoyuan Zhou, Daniel P Shoemaker, Christopher M Jaworski, Vinayak P Dravid, Joseph P HeremansAbstract:Thermoelectric heat-to-power generation is an attractive option for robust and environmentally friendly renewable energy production. Historically, the performance of Thermoelectric Materials has been limited by low efficiencies, related to the Thermoelectric figure-of-merit ZT. Nanostructuring Thermoelectric Materials have shown to enhance ZT primarily via increasing phonon scattering, beneficially reducing lattice thermal conductivity. Conversely, density-of-states (DOS) engineering has also enhanced electronic transport properties. However, successfully joining the two approaches has proved elusive. Herein, we report a Thermoelectric Materials system whereby we can control both nanostructure formations to effectively reduce thermal conductivity, while concurrently modifying the electronic structure to significantly enhance Thermoelectric power factor. We report that the Thermoelectric system PbTe–PbS 12% doped with 2% Na produces shape-controlled cubic PbS nanostructures, which help reduce lattice therm...
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microstructure lattice thermal conductivity correlation in nanostructured pbte0 7s0 3 Thermoelectric Materials
2010Co-Authors: Steven N Girard, Mercouri G Kanatzidis, Vinayak P DravidAbstract:The reduction of thermal conductivity, and a comprehensive understanding of the microstructural constituents that cause this reduction, represent some of the important challenges for the further development of Thermoelectric Materials with improved figure of merit. Model PbTe-based Thermoelectric Materials that exhibit very low lattice thermal conductivity have been chosen for this microstructure-thermal conductivity correlation study. The nominal PbTe{sub 0.7}S{sub 0.3} composition spinodally decomposes into two phases: PbTe and PbS. Orderly misfit dislocations, incomplete relaxed strain, and structure-modulated contrast rather than composition-modulated contrast are observed at the boundaries between the two phases. Furthermore, the samples also contain regularly shaped nanometer-scale precipitates. The theoretical calculations of the lattice thermal conductivity of the PbTe{sub 0.7}S{sub 0.3} material, based on transmission electron microscopy observations, closely aligns with experimental measurements of the thermal conductivity of a very low value, {approx}0.8 W m{sup -1} K{sup -1} at room temperature, approximately 35% and 30% of the value of the lattice thermal conductivity of either PbTe and PbS, respectively. It is shown that phase boundaries, interfacial dislocations, and nanometer-scale precipitates play an important role in enhancing phonon scattering and, therefore, in reducing the lattice thermal conductivity.
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New and old concepts in Thermoelectric Materials
2009Co-Authors: Joe Sootsman, D.Y.e Chung, Mercouri G KanatzidisAbstract:Herein we cover the key concepts in the field of Thermoelectric Materials research, present the current understanding, and show the latest developments. Current research is aimed at increasing the Thermoelectric figure of merit (ZT) by maximizing the power factor and/or minimizing the thermal conductivity. Attempts at maximizing the power factor include the development of new Materials, optimization of existing Materials by doping, and the exploration of nanoscale Materials. The minimization of the thermal conductivity can come through solid-solution alloying, use of Materials with intrinsically low thermal conductivity, and nanostructuring. Herein we describe the most promising bulk Materials with emphasis on results from the last decade. Single-phase bulk Materials are discussed in terms of chemistry, crystal structure, physical properties, and optimization of Thermoelectric performance. The new opportunities for enhanced performance bulk nanostructured composite Materials are examined and a look into the not so distant future is attempted.
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Recent Developments in Bulk Thermoelectric Materials
2006Co-Authors: George S. Nolas, Joe Poon, Mercouri G KanatzidisAbstract:Good Thermoelectric Materials possess low thermal conductivity while maximizing electric carrier transport. This article looks at various classes of Materials to understand their behavior and determine methods to modify or “tune” them to optimize their Thermoelectric properties. Whether it is the use of “rattlers” in cage structures such as skutterudites, or mixed-lattice atoms such as the complex half-Heusler alloys, the ability to manipulate the thermal conductivity of a material is essential in optimizing its properties for Thermoelectric applications.
Zhi-gang Chen - One of the best experts on this subject based on the ideXlab platform.
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flexible Thermoelectric Materials and generators challenges and innovations
2019Co-Authors: Yuan Wang, Xun Shi, Lidong Chen, Zhi-gang Chen, Jin Zou, Lei Yang, Xiaolei Shi, Matthew S DarguschAbstract:The urgent need for ecofriendly, stable, long-lifetime power sources is driving the booming market for miniaturized and integrated electronics, including wearable and medical implantable devices. Flexible Thermoelectric Materials and devices are receiving increasing attention, due to their capability to convert heat into electricity directly by conformably attaching them onto heat sources. Polymer-based flexible Thermoelectric Materials are particularly fascinating because of their intrinsic flexibility, affordability, and low toxicity. There are other promising alternatives including inorganic-based flexible Thermoelectrics that have high energy-conversion efficiency, large power output, and stability at relatively high temperature. Herein, the state-of-the-art in the development of flexible Thermoelectric Materials and devices is summarized, including exploring the fundamentals behind the performance of flexible Thermoelectric Materials and devices by relating Materials chemistry and physics to properties. By taking insights from carrier and phonon transport, the limitations of high-performance flexible Thermoelectric Materials and the underlying mechanisms associated with each optimization strategy are highlighted. Finally, the remaining challenges in flexible Thermoelectric Materials are discussed in conclusion, and suggestions and a framework to guide future development are provided, which may pave the way for a bright future for flexible Thermoelectric devices in the energy market.
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high performance snse Thermoelectric Materials progress and future challenge
2018Co-Authors: Li-dong Zhao, Zhi-gang Chen, Xiaolei Shi, Jin ZouAbstract:Thermoelectric Materials offer an alternative opportunity to tackle the energy crisis and environmental problems by enabling the direct solid-state energy conversion. As a promising candidate with full potentials for the next generation Thermoelectrics, tin selenide (SnSe) and its associated Thermoelectric Materials have been attracted extensive attentions due to their ultralow thermal conductivity and high electrical transport performance (power factor). To provide a thorough overview of recent advances in SnSe-based Thermoelectric Materials that have been revealed as promising Thermoelectric Materials since 2014, here, we first focus on the inherent relationship between the structural characteristics and the supreme Thermoelectric performance of SnSe, including the thermodynamics, crystal structures, and electronic structures. The effects of phonon scattering, pressure or strain, and oxidation behavior on the Thermoelectric performance of SnSe are discussed in detail. Besides, we summarize the current theoretical calculations to predict and understand the Thermoelectric performance of SnSe, and provide a comprehensive summary on the current synthesis, characterization, and Thermoelectric performance of both SnSe crystals and polycrystals, and their associated Materials. In the end, we point out the controversies, challenges and strategies toward future enhancements of the SnSe Thermoelectric Materials.
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Nanostructured Thermoelectric Materials: Current research and future challenge
2012Co-Authors: Zhi-gang Chen, Guang Hana, Lei Yanga, Lina Cheng, Jin ZouAbstract:The field of Thermoelectrics has long been recognized as a potentially transformative power generation technology and the field is now growing steadily due to their ability to convert heat directly into electricity and to develop cost-effective, pollution-free forms of energy conversion. Of various types of Thermoelectric Materials, nanostructured Materials have shown the most promise for commercial use because of their extraordinary Thermoelectric performances. This article aims to summarize the present progress of nanostructured Thermoelectrics and intends to understand and explain the underpinnings of the innovative breakthroughs in the last decade or so. We believed that recent achievements will augur the possibility for Thermoelectric power generation and cooling, and discuss several future directions which could lead to new exciting next generation of nanostructured Thermoelectrics.
Jihui Yang - One of the best experts on this subject based on the ideXlab platform.
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solid state explosive reaction for nanoporous bulk Thermoelectric Materials
2017Co-Authors: Kunpeng Zhao, Pengfei Qiu, Xun Shi, Wenqing Zhang, Jihui Yang, Haozhi Duan, Nunna Raghavendra, Yi Zeng, Lidong ChenAbstract:High-performance Thermoelectric Materials require ultralow lattice thermal conductivity typically through either shortening the phonon mean free path or reducing the specific heat. Beyond these two approaches, a new unique, simple, yet ultrafast solid-state explosive reaction is proposed to fabricate nanoporous bulk Thermoelectric Materials with well-controlled pore sizes and distributions to suppress thermal conductivity. By investigating a wide variety of functional Materials, general criteria for solid-state explosive reactions are built upon both thermodynamics and kinetics, and then successfully used to tailor material's microstructures and porosity. A drastic decrease in lattice thermal conductivity down below the minimum value of the fully densified Materials and enhancement in Thermoelectric figure of merit are achieved in porous bulk Materials. This work demonstrates that controlling Materials' porosity is a very effective strategy and is easy to be combined with other approaches for optimizing Thermoelectric performance.
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Magnetoelectric interaction and transport behaviours in magnetic nanocomposite Thermoelectric Materials
2017Co-Authors: Wenyu Zhao, Wanting Zhu, Xianli Su, Xinfeng Tang, Qingjie Zhang, Ping Wei, Jihui Yang, Yong Liu, Jing ShiAbstract:How to suppress the performance deterioration of Thermoelectric Materials in the intrinsic excitation region remains a key challenge. The magnetic transition of permanent magnet nanoparticles from ferromagnetism to paramagnetism provides an effective approach to finding the solution to this challenge. Here, we have designed and prepared magnetic nanocomposite Thermoelectric Materials consisting of BaFe12O19 nanoparticles and Ba0.3In0.3Co4Sb12 matrix. It was found that the electrical transport behaviours of the nanocomposites are controlled by the magnetic transition of BaFe12O19 nanoparticles from ferromagnetism to paramagnetism. BaFe12O19 nanoparticles trap electrons below the Curie temperature (TC) and release the trapped electrons above the TC, playing an ‘electron repository’ role in maintaining high figure of merit ZT. BaFe12O19 nanoparticles produce two types of magnetoelectric effect—electron spiral motion and magnon-drag thermopower—as well as enhancing phonon scattering. Our work demonstrates that the performance deterioration of Thermoelectric Materials in the intrinsic excitation region can be suppressed through the magnetic transition of permanent magnet nanoparticles.
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magnetoelectric interaction and transport behaviours in magnetic nanocomposite Thermoelectric Materials
2017Co-Authors: Wenyu Zhao, Xianli Su, Xinfeng Tang, Qingjie Zhang, Jihui Yang, Yimin ChaoAbstract:How to suppress the performance deterioration of Thermoelectric Materials in the intrinsic excitation region remains a key challenge. The magnetic transition of permanent magnet nanoparticles from ferromagnetism to paramagnetism provides an effective approach to finding the solution to this challenge. Here, we have designed and prepared magnetic nanocomposite Thermoelectric Materials consisting of BaFe12O19 nanoparticles and Ba0.3In0.3Co4Sb12 matrix. It was found that the electrical transport behaviours of the nanocomposites are controlled by the magnetic transition of BaFe12O19 nanoparticles from ferromagnetism to paramagnetism. BaFe12O19 nanoparticles trap electrons below the Curie temperature (TC) and release the trapped electrons above the TC, playing an ‘electron repository’ role in maintaining high figure of merit ZT. BaFe12O19 nanoparticles produce two types of magnetoelectric effect—electron spiral motion and magnon-drag thermopower—as well as enhancing phonon scattering. Our work demonstrates that the performance deterioration of Thermoelectric Materials in the intrinsic excitation region can be suppressed through the magnetic transition of permanent magnet nanoparticles. The ferromagnetic transition in magnetic nanoparticles embedded in magnetic nanocomposite Thermoelectric Materials is attributed to the trapping and release of electrons, which increases the performance of the Thermoelectric Materials.
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Rational Design of Advanced Thermoelectric Materials
2013Co-Authors: Jihui Yang, Hin Lap Yip, Alex K.y. JenAbstract:Advanced Thermoelectric technologies can drastically improve energy efficiencies of industrial infrastructures, solar cells, automobiles, aircrafts, etc. When a Thermoelectric device is used as a solid-state heat pump and/or as a power generator, its efficiency depends pivotally on three fundamental transport properties of Materials, namely, the thermal conductivity, electrical conductivity, and thermopower. The development of advanced Thermoelectric Materials is very challenging because these transport properties are interrelated. This paper reviews the physical mechanisms that have led to recent material advances. Progresses in both inorganic and organic Materials are summarized. While the majority of the contemporary effort has been focused on lowering the lattice thermal conductivity, the latest development in nanocomposites suggests that properly engineered interfaces are crucial for realizing the energy filtering effect and improving the power factor. We expect that the nanocomposite approach could be the focus of future Materials breakthroughs.
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Evaluation of half-Heusler compounds as Thermoelectric Materials based on the calculated electrical transport properties
2008Co-Authors: Jiong Yang, Huanming Li, Lidong Chen, Ting Wu, Wenqing Zhang, Jihui YangAbstract:A theoretical evaluation of the Thermoelectric-related electrical transport properties of 36 half-Heusler (HH) compounds, selected from more than 100 HHs, is carried out in this paper. The electronic structures and electrical transport properties are studied using ab initio calculations and the Boltzmann transport equation under the constant relaxation time approximation for charge carriers. The electronic structure results predict the band gaps of these HH compounds, and show that many HHs are narrow-band-gap semiconductors and, therefore, are potentially good Thermoelectric Materials. The dependence of Seebeck coefficient, electrical conductivity, and power factor on the Fermi level is investigated. Maximum power factors and the corresponding optimal p- or n-type doping levels, related to the Thermoelectric performance of Materials, are calculated for all HH compounds investigated, which certainly provide guidance to experimental work. The estimated optimal doping levels and Seebeck coefficients show reasonable agreement with the measured results for some HH systems. A few HHs are recommended to be potentially good Thermoelectric Materials based on our calculations.
