共查询到20条相似文献,搜索用时 15 毫秒
1.
Xing Tan Yaochun Liu Rui Liu Zhifang Zhou Chan Liu Jin‐Le Lan Qinghua Zhang Yuan‐Hua Lin Ce‐Wen Nan 《Liver Transplantation》2019,9(31)
Oxygen‐containing compounds are promising thermoelectric (TE) materials for their chemical and thermal stability. As compared with the high‐performance p‐type counterparts (e.g., ZT ≈1.5 for BiCuSeO), the enhancement of the TE performance of n‐type oxygen‐containing materials remains challenging due to their mediocre electrical conductivity and high thermal conductivity. Here, n‐type layered Bi2O2Se is reported as a potential TE material, of which the thermal conductivity and electrical transport properties can be effectively tuned via carrier engineering and hierarchical microstructure. By selective modification of insulating [Bi2O2]2+ layers with Ta dopant, carrier concentration can be increased by four orders of magnitude (from 1015 to 1019 cm?3) while relatively high carrier mobility can be maintained, thus greatly enhancing the power factors (≈451.5 µW K?2 m?1). Meanwhile, the hierarchical microstructure can be induced by Ta doping, and the phonon scattering can be strengthened by atomic point defects, nanodots of 5–10 nm and grains of sub‐micrometer level, which progressively suppresses the lattice thermal conductivity. Accordingly, the ZT value of Bi1.90Ta0.10O2Se reaches 0.36 at 773 K, a ≈350% improvement in comparison with that of the pristine Bi2O2Se. The average ZT value of 0.30 from 500 to 823 K is outstanding among n‐type oxygen‐containing TE materials. This work provides a desirable way for enhancing the ZT values in oxygen‐containing compounds. 相似文献
2.
Engineering the Thermoelectric Transport in Half‐Heusler Materials through a Bottom‐Up Nanostructure Synthesis
下载免费PDF全文
![点击此处可从《Liver Transplantation》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Huaizhou Zhao Binglei Cao Shanming Li Ning Liu Jiawen Shen Shan Li Jikang Jian Lin Gu Yanzhong Pei Gerald Jeffrey Snyder Zhifeng Ren Xiaolong Chen 《Liver Transplantation》2017,7(18)
Half‐Heusler (HH) alloys are among the best promising thermoelectric (TE) materials applicable for the middle‐to‐high temperature power generation. Despite of the large thermoelectric power factor and decent figure‐of‐merit ZT (≈1), their broad applications and enhancement on TE performance are limited by the high intrinsic lattice thermal conductivity (κL) due to insufficiencies of phonon scattering mechanisms, and the fewer powerful strategies associated with the microstructural engineering for HH materials. This study reports a bottom‐up nanostructure synthesis approach for these HH materials based on the displacement reaction between metal chlorides/bromides and magnesium (or lithium), followed by vacuum‐assisted spark plasma sintering process. The samples are featured with dense dislocation arrays at the grain boundaries, leading to a minimum κL of ≈1 W m?1 K?1 at 900 K and one of the highest ZT (≈1) and predicted η (≈11%) for n‐type Hf0.25Zr0.75NiSn0.97Sb0.03. Further manipulation on the dislocation defects at the grain boundaries of p‐type Nb0.8Ti0.2FeSb leads to enhanced maximum power factor of 47 × 10?4 W m?1 K?2 and the predicted η of ≈7.5%. Moreover, vanadium substitution in FeNb0.56V0.24Ti0.2Sb significantly promotes the η to ≈11%. This strategy can be extended to a broad range of advanced alloys and compounds for improved properties. 相似文献
3.
Subtle Roles of Sb and S in Regulating the Thermoelectric Properties of N‐Type PbTe to High Performance
下载免费PDF全文
![点击此处可从《Liver Transplantation》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Gangjian Tan Constantinos C. Stoumpos Si Wang Trevor P. Bailey Li‐Dong Zhao Ctirad Uher Mercouri G. Kanatzidis 《Liver Transplantation》2017,7(18)
A high ZT (thermoelectric figure of merit) of ≈1.4 at 900 K for n‐type PbTe is reported, through modifying its electrical and thermal properties by incorporating Sb and S, respectively. Sb is confirmed to be an amphoteric dopant in PbTe, filling Te vacancies at low doping levels (<1%), exceeding which it enters into Pb sites. It is found that Sb‐doped PbTe exhibits much higher carrier mobility than similar Bi‐doped materials, and accordingly, delivers higher power factors and superior ZT . The enhanced electronic transport is attributed to the elimination of Te vacancies, which appear to strongly scatter n‐type charge carriers. Building on this result, the ZT of Pb0.9875Sb0.0125Te is further enhanced by alloying S into the Te sublattice. The introduction of S opens the bandgap of PbTe, which suppresses bipolar conduction while simultaneously increasing the electron concentration and electrical conductivity. Furthermore, it introduces point defects and induces second phase nanostructuring, which lowers the lattice thermal conductivity to ≈0.5 W m?1 K?1 at 900 K, making this material a robust candidate for high‐temperature (500–900 K) thermoelectric applications. It is anticipated that the insights provided here will be an important addition to the growing arsenal of strategies for optimizing the performance of thermoelectric materials. 相似文献
4.
Three‐Stage Inter‐Orthorhombic Evolution and High Thermoelectric Performance in Ag‐Doped Nanolaminar SnSe Polycrystals
下载免费PDF全文
![点击此处可从《Liver Transplantation》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Lijuan Zhang Jianli Wang Qiao Sun Peng Qin Zhenxiang Cheng Zhenhua Ge Zhen Li Shixue Dou 《Liver Transplantation》2017,7(19)
The ultrahigh thermoelectric performance of SnSe‐based single crystals has attracted considerable interest in their polycrystalline counterparts. However, the temperature‐dependent structural transition in SnSe‐based thermoelectric materials and its relationship with their thermoelectric performance are not fully investigated and understood. In this work, nanolaminar SnSe polycrystals are prepared and characterized in situ using neutron and synchrotron powder diffraction measurements at various temperatures. Rietveld refinement results indicate that there is a complete inter‐orthorhombic evolution from Pnma to Cmcm by a series of layer slips and stretches along the a‐ and b‐axes over a 200 K temperature range. This phase transition leads to drastic enhancement of the carrier concentration and phonon scattering above 600 K. Moreover, the unique nanolaminar structure effectively enhances the carrier mobility of SnSe. Their grain and layer boundaries further improve the phonon scattering. These favorable factors result in a high ZT of 1.0 at 773 K for pristine SnSe polycrystals. The thermoelectric performances of polycrystalline SnSe are further improved by p‐type and n‐type dopants (i.e., doped with Ag and SnCl2, respectively), and new records of ZT are achieved in Ag0.015Sn0.985Se (ZT of 1.3 at 773 K) and SnSe0.985Cl0.015 (ZT of 1.1 at 773 K) polycrystals. 相似文献
5.
Shuo Chen Kevin C. Lukas Weishu Liu Cyril P. Opeil Gang Chen Zhifeng Ren 《Liver Transplantation》2013,3(9):1210-1214
Half‐Heusler n‐type thermoelectric materials MNiSn (M = Hf, Zr) have been shown to exhibit peak thermoelectric dimensionless figure‐of‐merit (ZT) of ~1.0 at 600–700 °C with a composition of Hf0.75Zr0.25NiSn0.99Sb0.01. This work demonstrates that it is possible to achieve the same ZT by reducing the concentration of the most expensive component Hf to one third of the previously reported best composition, i.e., Hf0.25Zr0.75NiSn0.99Sb0.01, which corresponds to an overall 50% reduction on material cost. The samples are prepared by ball milling the arc melted ingot and hot pressing the finely ground powders. The reduction of Hf concentration is crucial for such materials to be used in large‐scale waste heat recovery. 相似文献
6.
New Insight on Tuning Electrical Transport Properties via Chalcogen Doping in n‐type Mg3Sb2‐Based Thermoelectric Materials
下载免费PDF全文
![点击此处可从《Liver Transplantation》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Jiawei Zhang Lirong Song Kasper Andersen Borup Mads Ry Vogel Jørgensen Bo Brummerstedt Iversen 《Liver Transplantation》2018,8(16)
n‐type Mg3Sb1.5Bi0.5 has recently been discovered to be a promising thermoelectric material, yet the effective n‐type dopants are mainly limited to the chalcogens. This may be attributed to the limited chemical insight into the effects from different n‐type dopants. By comparing the effects of different chalcogen dopants Q (Q = S, Se, and Te) on thermoelectric properties, it is found that the chalcogen dopants Q become more efficient with decreasing electronegativity difference between Q and Mg, which is mainly due to the increasing carrier concentration and mobility. Using density functional theory calculations, it is shown that the improving carrier concentration originates from the increasing doping limit induced by the stabilizing extrinsic defect. Moreover, the increasing electron mobility with decreasing electronegativity difference between Q and Mg is attributed to the smaller effective mass resulting from the enhancing chemical bond covalency, which is supported by the decreasing theoretical density of states. According to the above trends, a simple guiding principle based on electronegativity is proposed to shed new light on n‐type doping in Zintl antimonides. 相似文献
7.
Hio‐Ieng Un Shawn A. Gregory Swagat K. Mohapatra Miao Xiong Elena Longhi Yang Lu Sergei Rigin Samik Jhulki Chi‐Yuan Yang Tatiana V. Timofeeva Jie‐Yu Wang Shannon K. Yee Stephen Barlow Seth R. Marder Jian Pei 《Liver Transplantation》2019,9(24)
Molecular doping is a powerful method to fine‐tune the thermoelectric properties of organic semiconductors, in particular to impart the requisite electrical conductivity. The incorporation of molecular dopants can, however, perturb the microstructure of semicrystalline organic semiconductors, which complicates the development of a detailed understanding of structure–property relationships. To better understand how the doping pathway and the resulting dopant counterion influence the thermoelectric performance and transport properties, a new dimer dopant, (N‐DMBI)2, is developed. Subsequently, FBDPPV is then n‐doped with dimer dopants (N‐DMBI)2, (RuCp*mes)2, and the hydride‐donor dopant N‐DMBI‐H. By comparing the UV–vis–NIR absorption spectra and morphological characteristics of the doped polymers, it is found that not only the doping mechanism, but also the shape of the counterion strongly influence the thermoelectric properties and transport characteristics. (N‐DMBI)2, which is a direct electron‐donating dopant with a comparatively small, relatively planar counterion, gives the best power factor among the three systems studied here. Additionally, temperature‐dependent conductivity and Seebeck coefficient measurements differ between the three dopants with (N‐DMBI)2 yielding the best thermoelectric properties. The results of this study of dopant effects on thermoelectric properties provide insight into guidelines for future organic thermoelectrics. 相似文献
8.
Thermoelectric materials can be used to harvest low‐grade heat that is otherwise dissipated to the environment. But the conventional thermoelectric materials that are semiconductors or semimetals, usually exhibit a Seebeck coefficient of much less than 1 mV K?1. They are expensive and consist of toxic elements as well. Here, it is demonstrated environmental benign flexible quasi‐solid state ionogels with giant Seebeck coefficient and ultrahigh thermoelectric properties. The ionogels made of ionic liquids and poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVDF‐HFP) can exhibit a giant Seebeck coefficient up to 26.1 mV K?1, the highest for electronic and ionic conductors. In addition, they have a high ionic conductivity of 6.7 mS cm?1 and a low thermal conductivity of 0.176 W m?1 K?1. Their thermoelectric figure of merit (ZT) is thus 0.75. The giant Seebeck coefficient is related to the ion‐dipole interaction between PVDF‐HFP and ionic liquids. Their application in ionic thermoelectric capacitors is also demonstrated for the conversion of intermittent heat into electricity. They are especially important to harvest the low‐grade thermal energy that is abundant on earth. 相似文献
9.
10.
11.
Wei‐Di Liu De‐Zhuang Wang Qingfeng Liu Wei Zhou Zongping Shao Zhi‐Gang Chen 《Liver Transplantation》2020,10(19)
High‐performance GeTe‐based thermoelectrics have been recently attracting growing research interest. Here, an overview is presented of the structural and electronic band characteristics of GeTe. Intrinsically, compared to low‐temperature rhombohedral GeTe, the high‐symmetry and high‐temperature cubic GeTe has a low energy offset between L and Σ points of the valence band, the reduced direct bandgap and phonon group velocity, and as a result, high thermoelectric performance. Moreover, their thermoelectric performance can be effectively enhanced through either carrier concentration optimization, band structure engineering (bandgap reduction, band degeneracy, and resonant state engineering), or restrained lattice thermal conductivity (phonon velocity reduction or phonon scattering). Consequently, the dimensionless figure of merit, ZT values, of GeTe‐based thermoelectric materials can be higher than 2. The mechanical and thermal stabilities of GeTe‐based thermoelectrics are highlighted, and it is found that they are suitable for practical thermoelectric applications except for their high cost. Finally, it is recognized that the performance of GeTe‐based materials can be further enhanced through synergistic effects. Additionally, proper material selection and module design can further boost the energy conversion efficiency of GeTe‐based thermoelectrics. 相似文献
12.
The rapid development of the concept of the “Internet of Things (IoT)” requires wearable devices with maintenance‐free batteries, and thermoelectric energy conversion based on large‐area flexible materials has attracted much attention. Among large‐area flexible materials, 2D materials, such as graphene and related materials, are promising for thermoelectric applications due to their excellent transport properties and large power factors. In this Review, both single‐crystalline and polycrystalline 2D materials are surveyed using the experimental reports on thermoelectric devices of graphene, black phosphorus, transition metal dichalcogenides, and other 2D materials. In particular, their carrier‐density dependent thermoelectric properties and power factors maximized by Fermi level tuning techniques are focused. The comparison of the relevant performances between 2D materials and commonly used thermoelectric materials reveals the significantly enhanced power factors in 2D materials. Moreover, the current progress in thermoelectric module applications using large‐area 2D material thin films is summarized, which consequently offers great potential for the use of 2D materials in large‐area flexible thermoelectric device applications. Finally, important remaining issues and future perspectives, such as preparation methods, thermal transports, device designs, and promising effects in 2D materials, are discussed. 相似文献
13.
Synergistically Optimizing Electrical and Thermal Transport Properties of BiCuSeO via a Dual‐Doping Approach
下载免费PDF全文
![点击此处可从《Liver Transplantation》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Yong Liu Li‐Dong Zhao Yingcai Zhu Yaochun Liu Fu Li Meijuan Yu Da‐Bo Liu Wei Xu Yuan‐Hua Lin Ce‐Wen Nan 《Liver Transplantation》2016,6(9)
The layered oxyselenide BiCuSeO system is known as one of the high‐performance thermoelectric materials with intrinsically low thermal conductivity. By employing atomic, nano‐ to mesoscale structural optimizations, low thermal conductivity coupled with enhanced electrical transport properties can be readily achieved. Upon partial substitution of Bi3+ by Ca2+ and Pb2+, the thermal conductivity can be reduced to as low as 0.5 W m?1 K?1 at 873 K through dual‐atomic point‐defect scattering, while a high power factor of ≈1 × 10?3 W cm?1 K?2 is realized over a broad temperature range from 300 to 873 K. The synergistically optimized power factor and intrinsically low thermal conductivity result in a high ZT value of ≈1.5 at 873 K for Bi0.88Ca0.06Pb0.06CuSeO, a promising candidate for high‐temperature thermoelectric applications. It is envisioned that the all‐scale structural optimization is critical for optimizing the thermoelectricity of quaternary compounds. 相似文献
14.
Biao Chen Huan Li Huaxiong Liu Xinqian Wang Fangxi Xie Yida Deng Wenbin Hu Kenneth Davey Naiqin Zhao Shi‐Zhang Qiao 《Liver Transplantation》2019,9(30)
ReS2 (rhenium disulfide) is a new transition‐metal dichalcogenide that exhibits 1T′ phase and extremely weak interlayer van der Waals interactions. This makes it promising as an anode material for sodium‐ion batteries. However, achieving both a high‐rate capability and a long‐life has remained a major research challenge. Here, a new composite is reported, in which both are realized for the first time. 1T′‐ReS2 is confined through strong interfacial interaction in a 2D‐honeycombed carbon nanosheets that comprise an rGO inter‐layer and a N‐doped carbon coating‐layer (rGO@ReS2@N‐C). The strong interfacial interaction between carbon and ReS2 increases overall conductivity and decreases Na+ diffusion resistance, whilst the intended 2D‐honeycombed carbon protective layer maintains structural morphology and electrochemical activity during long‐term cycling. These findings are confirmed by advanced characterization techniques, electrochemical measurement, and density functional theory calculation. The new rGO@ReS2@N‐C exhibits the greatest rate performance reported so far for ReS2 of 231 mAh g?1 at 10 A g?1. Significantly, this is together with ultra‐stable long‐term cycling of 192 mAh g?1 at 2 A g?1 after 4000 cycles. 相似文献
15.
Yu Xiao Haijun Wu Dongyang Wang Changlei Niu Yanling Pei Yang Zhang Ioannis Spanopoulos Ian Thomas Witting Xin Li Stephen J. Pennycook Gerald Jeffrey Snyder Mercouri G. Kanatzidis Li‐Dong Zhao 《Liver Transplantation》2019,9(17)
The Ag and In co‐doped PbTe, AgnPb100InnTe100+2n (LIST), exhibits n‐type behavior and features unique inherent electronic levels that induce self‐tuning carrier density. Results show that In is amphoteric in the LIST, forming both In3+ and In1+ centers. Through unique interplay of valence fluctuations in the In centers and conduction band filling, the electron carrier density can be increased from ≈3.1 × 1018 cm?3 at 323 K to ≈2.4 × 1019 cm?3 at 820 K, leading to large power factors peaking at ≈16.0 µWcm?1 K?2 at 873 K. The lone pair of electrons from In+ can be thermally continuously promoted into the conduction band forming In3+, consistent with the amphoteric character of In. Moreover, with rising temperature, the Fermi level shifts into the conduction band, which enlarges the optical band gap based on the Moss–Burstein effect, and reduces bipolar diffusion and thermal conductivity. Adding extra Ag in LIST improves the electrical transport properties and meanwhile lowers the lattice thermal conductivity to ≈0.40 Wm?1 K?1. The addition of Ag creates spindle‐shaped Ag2Te nanoprecipitates and atomic‐scale interstitials that scatter a broader set of phonons. As a result, a maximum ZT value ≈1.5 at 873 K is achieved in Ag6Pb100InTe102 (LIST). 相似文献
16.
17.
Christian Schumacher Klaus G. Reinsberg Lewis Akinsinde Sebastian Zastrow Sonja Heiderich William Toellner Geert Rampelberg Christophe Detavernier José A. C. Broekaert Kornelius Nielsch Julien Bachmann 《Liver Transplantation》2012,2(3):345-352
A systematic optimization of p‐type Sb2Te3 thermoelectric films made by potentiostatic electrodeposition on Au and stainless steel substrates is presented. The influence of the preparative parameters of deposition voltage, concentration, and the deposition method are investigated in a nitric acid solution. As a postdeposition step, the influence of annealing the films is investigated. The use of a potential‐controlled millisecond‐pulsed deposition method could improve both the morphology and the composition of the films. The samples are characterized in terms of composition, crystallinity, Seebeck coefficient, and electrical resistivity. Pulsed‐deposited films exhibit Seebeck coefficients of up to 160 μV K?1 and an electrical conductivity of 280 S cm?1 at room temperature, resulting in power factors of about 700 μW m?1 K?2. After annealing, power factors of maximum 852 μW m?1 K?2 are achieved. Although the annealing of DC‐deposited films significantly increased the power factor, they do not reach the values of the pulsed‐deposited films in the preannealing state. Structural analysis is performed with X‐ray diffraction and shows the crystalline structure of Sb2Te3 films. The performance is tuned by annealing of deposited films up to 300 °C under He atmosphere while performing in‐situ X‐ray diffraction and resistivity measurements. The chemical analysis of the films is performed by inductively coupled plasma optical emission spectroscopy (ICP‐OES) as well as scanning electron microscope energy dispersive X‐ray analysis (SEM‐EDX). 相似文献
18.
Yubo Luo Yun Zheng Zhongzhen Luo Shiqiang Hao Chengfeng Du Qinghua Liang Zhong Li Khiam Aik Khor Kedar Hippalgaonkar Jianwei Xu Qingyu Yan Chris Wolverton Mercouri G. Kanatzidis 《Liver Transplantation》2018,8(8)
It is reported that electron doped n‐type SnSe2 nanoplates show promising thermoelectric performance at medium temperatures. After simultaneous introduction of Se deficiency and Cl doping, the Fermi level of SnSe2 shifts toward the conduction band, resulting in two orders of magnitude increase in carrier concentration and a transition to degenerate transport behavior. In addition, all‐scale hierarchical phonon scattering centers, such as point defects, nanograin boundaries, stacking faults, and the layered nanostructures, cooperate to produce very low lattice thermal conductivity. As a result, an enhanced in‐plane thermoelectric figure of merit ZTmax of 0.63 is achieved for a 1.5 at% Cl doped SnSe1.95 pellet at 673 K, which is much higher than the corresponding in‐plane ZT of pure SnSe2 (0.08). 相似文献
19.
High‐Performance and Low‐Temperature Lithium–Sulfur Batteries: Synergism of Thermodynamic and Kinetic Regulation
下载免费PDF全文
![点击此处可从《Liver Transplantation》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Chao‐Ying Fan Yan‐Ping Zheng Xiao‐Hua Zhang Yan‐Hong Shi Si‐Yu Liu Han‐Chi Wang Xing‐Long Wu Hai‐Zhu Sun Jing‐Ping Zhang 《Liver Transplantation》2018,8(18)
The intrinsic polysulfides shuttle, resulting from not only concentration‐gradient diffusion but also slow conversion kinetics of polysulfides, bears the primary responsibility for the poor capacity and cycle stability of lithium–sulfur batteries (LSBs). Here, it is first presented that enriched edge sites derived from vertical standing and ultrathin 2D layered metal selenides (2DLMS) can simultaneously achieve the thermodynamic and kinetic regulation for polysulfides diffusion, which is systematically elucidated through theoretical calculation, electrochemical characterization, and spectroscopic/microscopic analysis. When employed to fabricate compact coating layer of separator, an ultrahigh capacity of 1338.7 mA h g?1 is delivered after 100 cycles at 0.2 C, which is the best among the reports. Over 1000 cycles, the cell still maintains the capacity of 546.8 mA h g?1 at 0.5 C. Moreover, the cell exhibits outstanding capacities of 1106.2 and 865.7 mA h g?1 after 100 cycles at stern temperature of 0 and ?25 °C. The superior low‐temperature performance is appealing for extended practical application of LSBs. Especially, in view of the economy, the 2DLMS is recycled as an anode of lithium‐ion and sodium‐ion batteries after finishing the test of LSBs. The low‐cost and scalable 2DLMS with enriched egde sites open a new avenue for the perfect regulation of the sulfur electrode. 相似文献
20.
Yubo Luo Songting Cai Xia Hua Haijie Chen Qinghua Liang Chengfeng Du Yun Zheng Junhua Shen Jianwei Xu Chris Wolverton Vinayak P. Dravid Qingyu Yan Mercouri G. Kanatzidis 《Liver Transplantation》2019,9(2)
Single crystalline SnSe is one of the most intriguing new thermoelectric materials but the thermoelectric performance of polycrystalline SnSe seems to lag significantly compared to that of a single crystal. Here an effective strategy for enhancing the thermoelectric performance of p‐type polycrystalline SnSe by Ag/Na dual‐doping and Ag8SnSe6 (STSe) nanoprecipitates is reported. The Ag/Na dual‐doping leads to a two orders of magnitude increase in carrier concentration and a convergence of valence bands (VBM1 and VBM5), which in turn results in sharp enhancement of electrical conductivities and high Seebeck coefficients in the Ag/Na dual‐doped samples. Additionally, the SnSe matrix becomes nanostructured with dispersed nanoprecipitates of the compound Ag8SnSe6, which further strengthens the scattering of phonons. Specifically, ≈20% reduction in the already ultralow lattice thermal conductivity is realized for the Sn0.99Na0.01Se–STSe sample at 773 K compared to the thermal conductivity of pure SnSe. Consequently, a peak thermoelectric figure of merit ZT of 1.33 at 773 K with a high average ZT (ZTave) value of 0.91 (423–823 K) is achieved for the Sn0.99Na0.01Se–STSe sample. 相似文献