共查询到11条相似文献,搜索用时 0 毫秒
1.
Xiaolei Shi Angyin Wu Tianli Feng Kun Zheng Weidi Liu Qiang Sun Min Hong Sokrates T. Pantelides Zhi‐Gang Chen Jin Zou 《Liver Transplantation》2019,9(11)
Herein, a high figure of merit (ZT) of ≈1.7 at 823 K is reported in p‐type polycrystalline Cd‐doped SnSe by combining cation vacancies and localized‐lattice engineering. It is observed that the introduction of Cd atoms in SnSe lattice induce Sn vacancies, which act as p‐type dopants. A combination of facile solvothermal synthesis and fast spark plasma sintering technique boosts the Sn vacancy to a high level of ≈2.9%, which results in an optimum hole concentration of ≈2.6 × 1019 cm?3 and an improved power factor of ≈6.9 µW cm?1 K?2. Simultaneously, a low thermal conductivity of ≈0.33 W m?1 K?1 is achieved by effective phonon scattering at localized crystal imperfections, as observed by detailed structural characterizations. Density functional theory calculations reveal that the role of Cd atoms in the SnSe lattice is to reduce the formation energy of Sn vacancies, which in turn lower the Fermi level down into the valence bands, generating holes. This work explores the fundamental Cd‐doping mechanisms at the nanoscale in a SnSe matrix and demonstrates vacancy and localized‐lattice engineering as an effective approach to boosting thermoelectric performance. The work provides an avenue in achieving high‐performance thermoelectric properties of materials. 相似文献
2.
Chlorine‐Enabled Electron Doping in Solution‐Synthesized SnSe Thermoelectric Nanomaterials 下载免费PDF全文
Guang Han Srinivas R. Popuri Heather F. Greer Lourdes F. Llin Jan‐Willem G. Bos Wuzong Zhou Douglas J. Paul Hervé Ménard Andrew R. Knox Andrea Montecucco Jonathan Siviter Elena A. Man Wen‐guang Li Manosh C. Paul Min Gao Tracy Sweet Robert Freer Feridoon Azough Hasan Baig Tapas K. Mallick Duncan H. Gregory 《Liver Transplantation》2017,7(13)
An aqueous solution method is developed for the facile synthesis of Cl‐containing SnSe nanoparticles in 10 g quantities per batch. The particle size and Cl concentration of the nanoparticles can be efficiently tuned as a function of reaction duration. Hot pressing produces n‐type Cl‐doped SnSe nanostructured compacts with thermoelectric power factors optimized via control of Cl dopant concentration. This approach, combining an energy‐efficient solution synthesis with hot pressing, provides a simple, rapid, and low‐cost route to high performance n‐type SnSe thermoelectric materials. 相似文献
3.
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
4.
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
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
5.
Three‐Stage Inter‐Orthorhombic Evolution and High Thermoelectric Performance in Ag‐Doped Nanolaminar SnSe Polycrystals 下载免费PDF全文
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
6.
Mohamad I. Nugraha Hyunho Kim Bin Sun Saheena Desai F. Pelayo Garcia de Arquer Edward H. Sargent Husam N. Alshareef Derya Baran 《Liver Transplantation》2019,9(28)
Colloidal quantum dots (CQDs) are attractive materials for thermoelectric applications due to their simple and low‐cost processing; advantageously, they also offer low thermal conductivity and high Seebeck coefficient. To date, the majority of CQD thermoelectric films reported upon have been p‐type, while only a few reports are available on n‐type films. High‐performing n‐ and p‐type films are essential for thermoelectric generators (TEGs) with large output voltage and power. Here, high‐thermoelectric‐performance n‐type CQD films are reported and showcased in high‐performance all‐CQD TEGs. By engineering the electronic coupling in the films, a thorough removal of insulating ligands is achieved and this is combined with excellent surface trap passivation. This enables a high thermoelectric power factor of 24 µW m?1 K?2, superior to previously reported n‐type lead chalcogenide CQD films operating near room temperature (<1 µW m?1 K?2). As a result, an all‐CQD film TEG with a large output voltage of 0.25 V and a power density of 0.63 W m?2 at ?T = 50 K is demonstrated, which represents an over fourfold enhancement to previously reported p‐type only CQD TEGs. 相似文献
7.
Enhancement of Thermoelectric Performance of n‐Type PbSe by Cr Doping with Optimized Carrier Concentration 下载免费PDF全文
Qian Zhang Eyob Kebede Chere Kenneth McEnaney Mengliang Yao Feng Cao Yizhou Ni Shuo Chen Cyril Opeil Gang Chen Zhifeng Ren 《Liver Transplantation》2015,5(8)
Ti, V, Cr, Nb, and Mo are found to be effective at increasing the Seebeck coefficient and power factor of n‐type PbSe at temperatures below 600 K. It is found that the higher Seebeck coefficients and power factors are due to higher Hall mobility ≈1000 cm2 V?1s?1 at lower carrier concentration. A larger average ZT value (relevant for applications) can be obtained by an optimization of carrier concentration to ≈1018–1019 cm?3. Even though the highest room temperature power factor ≈3.3 × 10?3 W m?1 K?2 is found in 1 at% Mo‐doped PbSe, the highest ZT is achieved in Cr‐doped PbSe. Combined with the lower thermal conductivity, ZT is improved to ≈0.4 at room temperature and peak ZTs of ≈1.0 are observed at ≈573 K for Pb0.9925Cr0.0075Se and ≈673 K for Pb0.995Cr0.005Se. The calculated device efficiency of Pb0.995Cr0.005Se is as high as ≈12.5% with cold side 300 K and hot side 873 K, higher than those of all the n‐type PbSe materials reported in the literature. 相似文献
8.
Cheng Chang Dongyang Wang Dongsheng He Wenke He Fangyuan Zhu Guangtao Wang Jiaqing He Li‐Dong Zhao 《Liver Transplantation》2019,9(28)
Thermoelectric technology enables direct conversion between heat and electricity. The conversion efficiency of a thermoelectric device is determined by the average dimensionless figure of merit ZTave. Here, a record high ZTave of ≈1.34 in the range of 300–723 K in n‐type SnSe based crystals is reported. The remarkable thermoelectric performance derives from the high power factor and the reduced thermal conductivity in the whole temperature range. The high power factor is realized by promoting the continuous phase transition in SnSe crystals through alloying PbSe, which results in a higher symmetry of the crystal structure and the correspondingly modified electronic band structure. Moreover, PbSe alloying induces mass and strain fluctuations, which enables the suppression of thermal transport. These findings provide a new strategy to enhance the thermoelectric performance for the continuous phase transition materials. 相似文献
9.
High Band Degeneracy Contributes to High Thermoelectric Performance in p‐Type Half‐Heusler Compounds 下载免费PDF全文
Chenguang Fu Tiejun Zhu Yanzhong Pei Hanhui Xie Heng Wang G. Jeffrey Snyder Yong Liu Yintu Liu Xinbing Zhao 《Liver Transplantation》2014,4(18)
Half‐Heusler (HH) compounds are important high temperature thermoelectric (TE) materials and have attracted considerable attention in the recent years. High figure of merit zT values of 0.8 to 1.0 have been obtained in n‐type ZrNiSn‐based HH compounds. However, developing high performance p‐type HH compounds are still a big challenge. Here, it is shown that a new p‐type HH alloy with a high band degeneracy of 8, Ti‐doped FeV0.6Nb0.4Sb, can achieve a high zT of 0.8, which is one of the highest reported values in the p‐type HH compounds. Although the band effective mass of this system is found to be high, which may lead to a low mobility, its low deformation potential and low alloy scattering potential both contribute to a reasonably high mobility. The enhanced phonon scattering by alloying leads to a reduced lattice thermal conductivity. The achieved high zT demonstrates that the p‐type Ti doped FeV0.6Nb0.4Sb HH alloys are promising as TE materials and offer an excellent TE performance match with n‐type ones for high temperature power generation. 相似文献
10.
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
11.
Tyler J. Slade Trevor P. Bailey Jann A. Grovogui Xia Hua Xiaomi Zhang Jimmy Jiahong Kuo Ido Hadar G. Jeffrey Snyder Chris Wolverton Vinayak P. Dravid Ctirad Uher Mercouri G. Kanatzidis 《Liver Transplantation》2019,9(30)
PbSe is an attractive thermoelectric material due to its favorable electronic structure, high melting point, and lower cost compared to PbTe. Herein, the hitherto unexplored alloys of PbSe with NaSbSe2 (NaPbmSbSem+2) are described and the most promising p‐type PbSe‐based thermoelectrics are found among them. Surprisingly, it is observed that below 500 K, NaPbmSbSem+2 exhibits unorthodox semiconducting‐like electrical conductivity, despite possessing degenerate carrier densities of ≈1020 cm?3. It is shown that the peculiar behavior derives from carrier scattering by the grain boundaries. It is further demonstrated that the high solubility of NaSbSe2 in PbSe augments both the thermoelectric properties while maintaining a rock salt structure. Namely, density functional theory calculations and photoemission spectroscopy demonstrate that introduction of NaSbSe2 lowers the energy separation between the L‐ and Σ‐valence bands and enhances the power factors under 700 K. The crystallographic disorder of Na+, Pb2+, and Sb3+ moreover provides exceptionally strong point defect phonon scattering yielding low lattice thermal conductivities of 1–0.55 W m‐1 K‐1 between 400 and 873 K without nanostructures. As a consequence, NaPb10SbSe12 achieves maximum ZT ≈1.4 near 900 K when optimally doped. More importantly, NaPb10SbSe12 maintains high ZT across a broad temperature range, giving an estimated record ZTavg of ≈0.64 between 400 and 873 K, a significant improvement over existing p‐type PbSe thermoelectrics. 相似文献