224 results on '"An, Ran"'
Search Results
2. Phase-modulated mechanical and thermoelectric properties of Ag2S1-xTex ductile semiconductors
- Author
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Liming Peng, Shiqi Yang, Tian-Ran Wei, Pengfei Qiu, Jiong Yang, Zhen Zhang, Xun Shi, and Lidong Chen
- Subjects
Thermoelectric materials ,Ag2S-Ag2Te ductile semiconductors ,Phase transition ,Mechanical properties ,Transport properties ,Materials of engineering and construction. Mechanics of materials ,TA401-492 - Abstract
By virtue of the excellent plasticity and tunable transport properties, Ag2S-based materials demonstrate an intriguing prospect for flexible or hetero-shaped thermoelectric applications. Among them, Ag2S1-xTex exhibits rich and interesting variations in crystal structure, mechanical and thermoelectric transport properties. However, Te alloying obviously introduces extremely large order-disorder distributions of cations and anions, leading to quite complicated crystal structures and thermoelectric properties. Detailed composition-structure-performance correlation of Ag2S1-xTex still remains to be established. In this work, we designed and prepared a series of Ag2S1-xTex (x = 0–0.3) materials with low Te content. We discovered that the monoclinic-to-cubic phase transition occurs around x = 0.16 at room temperature. Te alloying plays a similar role as heating in facilitating this monoclinic-to-cubic phase transition, which is analyzed based on the thermodynamic principles. Compared with the monoclinic counterparts, the cubic-structured phases are more ductile and softer in mechanical properties. In addition, the cubic phases show a degenerately semiconducting behavior with higher thermoelectric performance. A maximum zT = 0.8 at 600 K and bending strain larger than 20% at room temperature were obtained in Ag2S0.7Te0.3. This work provides a useful guidance for designing Ag2S-based alloys with enhanced plasticity and high thermoelectric performance.
- Published
- 2022
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3. Approaching crystal's limit of thermoelectrics by nano-sintering-aid at grain boundaries.
- Author
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Lei, Jingdan, Zhao, Kunpeng, Liao, Jincheng, Yang, Shiqi, Zhang, Ziming, Wei, Tian-Ran, Qiu, Pengfei, Zhu, Min, Chen, Lidong, and Shi, Xun
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SINGLE crystals ,CRYSTAL lattices ,THERMOELECTRIC materials ,POLYCRYSTALS ,THERMAL conductivity ,PHONON scattering - Abstract
Grain boundary plays a vital role in thermoelectric transports, leading to distinct properties between single crystals and polycrystals. Manipulating the grain boundary to realize good thermoelectric properties in polycrystals similar as those of single crystals is a long-standing task, but it is quite challenging. Herein, we develop a liquid-phase sintering strategy to successfully introduce Mg
2 Cu nano-sintering-aid into the grain boundaries of Mg3 (Bi, Sb)2 -based materials. The nano-aid helps to enlarge the average grain size to 23.7 μm and effectively scatter phonons, leading to excellent electrical transports similar as those of single crystals and ultralow lattice thermal conductivity as well as exceptional thermoelectric figure of merit (1.5 at 500 K) and conversion efficiency (7.4% under temperature difference of 207 K). This work provides a simple but effective strategy for the fabrication of high-performance polycrystals for large-scale applications. The authors develop a liquid-phase sintering strategy to effectively enlarge material's grain sizes, thereby achieving single crystal-like electronic transport properties in polycrystalline Mg3 (Bi, Sb)2 . [ABSTRACT FROM AUTHOR]- Published
- 2024
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4. Advanced Design and Manufacturing Approaches for Structures with Enhanced Thermal Management Performance: A Review.
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Sun, Qidong, Zhi, Geng, Zhou, Sheng, Dong, Xu, Shen, Qianye, Tao, Ran, and Qi, Junfeng
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PHASE change materials ,THERMOELECTRIC materials ,HEAT exchangers ,HEAT transfer ,BIOMIMICRY ,HEAT pipes ,THERMOELECTRIC generators - Abstract
Advanced design methods and manufacturing techniques are crucial for developing thermal management structures, essential for the efficient operation of complex equipment. This study provides a thorough review of design methodologies and advanced manufacturing technologies for thermal management materials and structures. It identifies key challenges and critically evaluates the integration of innovative design principles, such as biomimicry and topology optimization, into thermal management solutions. The analysis delves into the evolution of design theories and preparation techniques, with a specific focus on modern needs and research directions, particularly highlighting components fabricated using additive manufacturing and their effectiveness in meeting advanced thermal management requirements. Current research focuses on designing structures tailored to various cooling methods, including air‐cooling, liquid‐cooling, heat exchanger cooling, and heat pipe cooling. These designs utilize phase change materials, electrocaloric cooling, and thermoelectric cooling materials to achieve optimal thermal management performance. Additionally, emerging innovations like solid‐liquid mixed heat transfer and the elastocaloric effect are garnering increased interest. Enhancing the design of thermal management structures through rigorous numerical simulations is critical for improving engineering applicability. However, overcoming challenges related to the commercialization and practical utilization of these advanced structures remains a pressing need. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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5. High-Throughput Screening of High-Performance Thermoelectric Materials with Gibbs Free Energy and Electronegativity
- Author
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Guiying Xu, Jiakai Xin, Hao Deng, Ran Shi, Guangbing Zhang, and Ping Zou
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high-throughput screening ,thermoelectric materials ,Gibbs free energy ,electronegativity ,screening criteria for thermoelectric materials ,Technology ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Microscopy ,QH201-278.5 ,Descriptive and experimental mechanics ,QC120-168.85 - Abstract
Thermoelectric (TE) materials are an important class of energy materials that can directly convert thermal energy into electrical energy. Screening high-performance thermoelectric materials and improving their TE properties are important goals of TE materials research. Based on the objective relationship among the molar Gibbs free energy (Gm), the chemical potential, the Fermi level, the electronegativity (X) and the TE property of a material, a new method for screening TE materials with high throughput is proposed. This method requires no experiments and no first principle or Ab initio calculation. It only needs to find or calculate the molar Gibbs free energy and electronegativity of the material. Here, by calculating a variety of typical and atypical TE materials, it is found that the molar Gibbs free energy of Bi2Te3 and Sb2Te3 from 298 to 600 K (Gm = −130.20~−248.82 kJ/mol) and the electronegativity of Bi2Te3 and Sb2Te3 and PbTe (X = 1.80~2.21) can be used as criteria to judge the potential of materials to become high-performance TE materials. For good TE compounds, Gm and X are required to meet the corresponding standards at the same time. By taking Gm = −130.20~−248.82 kJ/mol and X = 1.80~2.21 as screening criteria for high performance TE materials, it is found that the Gm and X of all 15 typical TE materials and 9 widely studied TE materials meet the requirement very well, except for the X of Mg2Si, and 64 pure substances are screened as potential TE materials from 102 atypical TE materials. In addition, with reference to their electronegativity, 44 pure substances are selected directly from a thermochemical data book as potential high-performance TE materials. A particular finding is that several carbides, such as Be2C, CaC2, BaC2, SmC2, TaC and NbC, may have certain TE properties. Because the Gm and X of pure substances can be easily found in thermochemical data books and calculated using the X of pure elements, respectively, the Gm and X of materials can be used as good high-throughput screening criteria for predicting TE properties.
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- 2023
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6. Metavalent Bonding in Cubic SnSe Alloys Improves Thermoelectric Properties over a Broad Temperature Range.
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Lin, Nan, Han, Shuai, Ghosh, Tanmoy, Schön, Carl‐Friedrich, Kim, Dasol, Frank, Jonathan, Hoff, Felix, Schmidt, Thomas, Ying, Pingjun, Zhu, Yuke, Häser, Maria, Shen, Minghao, Liu, Ming, Sui, Jiehe, Cojocaru‐Mirédin, Oana, Zhou, Chongjian, He, Ran, Wuttig, Matthias, and Yu, Yuan
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ATOM-probe tomography ,ALLOYS ,THERMOELECTRIC materials ,LOW temperatures ,OPTICAL constants ,CHEMICAL bonds ,COSMIC abundances - Abstract
Monocrystalline SnSe is one of the most promising thermoelectric materials with outstanding performance and a high abundance of constituting elements. However, polycrystalline SnSe, which is more robust for applications, only shows large figure‐of‐merit (zT) values in its high‐symmetry phase. Stabilizing the high‐symmetry phase at low temperatures can thus enhance the average zT value over a broad temperature range. In this work, the high‐symmetry rock‐salt SnSe phase is successfully obtained by alloying SnSe with AgVVI2 compounds (V = Sb, Bi; VI = Se, Te). These cubic SnSe phases show a unique portfolio of properties including a high optical dielectric constant, a large maximum of optical absorption, a large Born effective charge, and abnormal bond‐breaking behavior in laser‐assisted atom probe tomography. All of these characteristics are indicative of metavalent bonding. In contrast, the Pnma phase of SnSe employs covalent bonding. The enhanced symmetry at low temperatures is realized by tailoring chemical bonding. Concomitantly, zT near room temperature is increased by a factor of more than 10 from the pristine Pnma SnSe to Fm3¯${{\bar{3}}}$m SnSe alloys. This provides insights into the enhancement of the thermoelectric performance of SnSe and other chalcogenides over a broad temperature range by manipulating the chemical bonds. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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7. Precision Interface Engineering of CuNi Alloys by Powder ALD Toward Better Thermoelectric Performance.
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He, Shiyang, Bahrami, Amin, Jung, Chanwon, Zhang, Xiang, He, Ran, Ren, Zhifeng, Zhang, Siyuan, and Nielsch, Kornelius
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ALLOY powders ,ATOMIC layer deposition ,THERMOELECTRIC materials ,SEEBECK coefficient ,ENGINEERING ,ALUMINUM oxide ,ELECTRIC conductivity - Abstract
The main bottleneck in obtaining high‐performance thermoelectric (TE) materials is identified as how to decouple the strong interrelationship between electrical and thermal parameters. Herein, a precise interface modification approach based on the powder atomic layer deposition (ALD) technology is presented to enhance the performance of CuNi alloys. ZnO and Al2O3 layers as well as their combinations are deposited on the surface of powders, typically in 10–100 ALD cycles, and their effects on the TE performance of bulks is thoroughly investigated. The enhancement of the Seebeck coefficient, caused by the energy filtering effect, compensates for the electrical conductivity deterioration due to the low electrical conductivity of oxide layers. Furthermore, the oxide layers may significantly increase the phonon scattering. Therefore, to reduce the resistivity of coating layer, a multilayer structure is deposited on the surface of powders by inserting Al2O3 into ZnO. The accurate microstructure characterization shows that the Al atoms diffused into ZnO and realized the doping effect after pressing. Al diffusion has the potential to increase the electrical conductivity and complexity of coating layers. Compared to pure CuNi, zT increases by 128% due to the decrease in resistivity and stronger phonon scattering in phase boundaries. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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8. Amorphous‐Like Ultralow Thermal Transport in Crystalline Argyrodite Cu7PS6.
- Author
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Shen, Xingchen, Ouyang, Niuchang, Huang, Yuling, Tung, Yung‐Hsiang, Yang, Chun‐Chuen, Faizan, Muhammad, Perez, Nicolas, He, Ran, Sotnikov, Andrei, Willa, Kristin, Wang, Chen, Chen, Yue, and Guilmeau, Emmanuel
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PHONON scattering ,TRANSPORT theory ,THERMAL conductivity ,PHASE transitions ,THERMOELECTRIC materials ,HEAT conduction ,LATTICE dynamics - Abstract
Due to their amorphous‐like ultralow lattice thermal conductivity both below and above the superionic phase transition, crystalline Cu‐ and Ag‐based superionic argyrodites have garnered widespread attention as promising thermoelectric materials. However, despite their intriguing properties, quantifying their lattice thermal conductivities and a comprehensive understanding of the microscopic dynamics that drive these extraordinary properties are still lacking. Here, an integrated experimental and theoretical approach is adopted to reveal the presence of Cu‐dominated low‐energy optical phonons in the Cu‐based argyrodite Cu7PS6. These phonons yield strong acoustic‐optical phonon scattering through avoided crossing, enabling ultralow lattice thermal conductivity. The Unified Theory of thermal transport is employed to analyze heat conduction and successfully reproduce the experimental amorphous‐like ultralow lattice thermal conductivities, ranging from 0.43 to 0.58 W m−1 K−1, in the temperature range of 100–400 K. The study reveals that the amorphous‐like ultralow thermal conductivity of Cu7PS6 stems from a significantly dominant wave‐like conduction mechanism. Moreover, the simulations elucidate the wave‐like thermal transport mainly results from the contribution of Cu‐associated low‐energy overlapping optical phonons. This study highlights the crucial role of low‐energy and overlapping optical modes in facilitating amorphous‐like ultralow thermal transport, providing a thorough understanding of the underlying complex dynamics of argyrodites. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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9. Impact of Various Dopants on Thermoelectric Transport Properties of Polycrystalline GeSb2Te4.
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Jiang, Yihan, Pan, Zhenyu, Huang, Haoran, Wan, Shun, Chen, Heyang, Zhao, Kunpeng, Wei, Tian‐Ran, and Shi, Xun
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THERMOELECTRIC materials ,ELECTRIC conductivity ,PHASE change materials ,SEEBECK coefficient ,CARRIER density ,CHALCOGENS - Abstract
GeSb2Te4 (GST124), one of the well‐known phase‐change materials for nonvolatile memory and rewritable optical storage, has been recently found to be promising thermoelectric materials with low lattice thermal conductivity and high electrical conductivity. However, its thermoelectric performance is greatly restricted by the excessively high hole concentration. Herein, the impact of a series of group IIIA (Al, Ga, In) and group VIA (S, Se) dopants on the electrical transport properties of polycrystalline GST124 has been studied. It is found that element sulfur (S) has the best doping efficiency because the GeS bonds are very strong and ionic that are beneficial for suppressing Ge vacancies to reduce the carrier concentration. Meanwhile, element indium (In) also shows decent doping efficiency because its ionic radius is close to the Ge ion and the InTe bonds have moderate bonding strength. Moreover, In doping introduces a resonant level in the valence band, leading to enhanced Seebeck coefficient and power factor. A high figure of merit (zT)of 0.73 at 700 K and an average zT of 0.48 over 300–750 K are obtained in Ge0.92In0.08Sb2Te4, which are 26% and 66% higher than pristine GST124. This study will advance the understanding and development of high‐performance GeSbTe‐based thermoelectric materials. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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10. Enhanced thermoelectric performance and mechanical strength in GeTe enable power generation and cooling.
- Author
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Zhu, Jianglong, Zhang, Fujie, Tai, Yilin, Tan, Xiaobo, Deng, Qian, Nan, Pengfei, Cheng, Ruihuan, Xia, Chengliang, Chen, Yue, Ge, Binghui, and Ang, Ran
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THERMOELECTRIC materials ,SEEBECK coefficient ,CARRIER density ,VICKERS hardness ,THERMAL conductivity ,QUALITY factor ,THERMOELECTRIC generators - Abstract
Finding a real thermoelectric (TE) material that excels in various aspects of TE performance, mechanical properties, TE power generation, and cooling is challenging for its commercialization. Herein, we report a novel multifunctional Ge0.78Cd0.06Pb0.1Sb0.06Te material with excellent TE performance and mechanical strength, which is utilized to construct candidate TE power generation and cooling devices near room temperature. Specifically, the effectiveness of band convergence, combined with optimized carrier concentration and electronic quality factor, distinctly boosts the Seebeck coefficient, thus greatly improving the power factor. Advanced electron microscopy observation indicates that complex multi‐scale hierarchical structures and strain field distributions lead to ultra‐low lattice thermal conductivity, and also effectively enhance mechanical properties. High ZT ~ 0.6 at 303 K, average ZTave ~ 1.18 from 303 to 553 K, and Vickers hardness of ~200 Hv in Ge0.78Cd0.06Pb0.1Sb0.06Te are obtained synchronously. Particularly, a 7‐pair TE cooling device with a maximum ΔT of ~45.9 K at Th = 328 K, and a conversion efficiency of ~5.2% at Th = 553 K achieving in a single‐leg device. The present findings demonstrate a unique approach to developing superior multifunctional GeTe‐based alloys, opening up a promising avenue for commercial applications. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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11. High‐Entropy Cubic Pseudo‐Ternary Ag2(S, Se, Te) Materials With Excellent Ductility and Thermoelectric Performance.
- Author
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Chen, Heyang, Shao, Chenlu, Huang, Shaoji, Gao, Zhiqiang, Huang, Haoran, Pan, Zhenyu, Zhao, Kunpeng, Qiu, Pengfei, Wei, Tian‐Ran, and Shi, Xun
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DUCTILITY ,PHASE transitions ,THERMOELECTRIC materials ,THERMAL conductivity ,POWER density ,ELECTRONIC equipment ,CHALCOGENS - Abstract
The discovery of ductile Ag2(S, Se, Te) materials opens a new avenue toward high‐performance flexible/hetero‐shaped thermoelectrics. Specifically, the cubic‐structured materials are quite attractive by combining remarkable plasticity, decent thermoelectric figure of merit (zT), and no phase transition above room temperature. However, such materials are quite few and the understanding is inadequate on their mechanical and thermoelectric properties. Enlightened by the high‐entropy principles, a series of pseudo‐ternary Ag2S‐Ag2Se‐Ag2Te alloys is designed and comprehensive diagrams of composition‐structure‐plasticity‐zT are compiled. Subsequently, the compositional region for the cubic phase is outlined. As a high‐entropy example featuring with anion‐site alloying and disordered Ag ions, Ag2‐xS1/3Se1/3Te1/3 materials exhibit impressively large elongations of 60–97%, ultralow lattice thermal conductivities of ≈0.2 W m−1 K−1, and decent zT values of 0.45 at 300 K, 0.8 at 460 K. The materials can be readily rolled into thin foils, showing excellent flexibility. Finally, a six‐leg in‐plane device is fabricated, achieving an output voltage of 13.6 mV, a maximal power of 12.8 µW, and a power density of 14.3 W m−2 under the temperature difference of 30 K, much higher than the organic counterparts. This study largely enriches the members of cubic ductile inorganic materials for the applications in flexible and hetero‐shaped energy and electronic devices. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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12. Unique Semi‐Coherent Nanostructure Advancing Thermoelectrics of N‐Type PbSe.
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Deng, Qian, Zhang, Fujie, Nan, Pengfei, Zhang, Ziyou, Gan, Lin, Chen, Zhiqiang, Ge, Binghui, Dong, Hongliang, Mao, Ho‐kwang, and Ang, Ran
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PHONON scattering ,THERMOELECTRIC materials ,SEEBECK coefficient ,THERMAL conductivity ,CHARGE carrier mobility ,CONDUCTION bands - Abstract
Introducing nanostructures into bulk thermoelectric materials is an effective strategy for reducing lattice thermal conductivity (κlat). However, large numbers of hanging bonds emerge on account of lattice mismatch usually at the interfaces between nanostructures and matrix, thereby significantly deteriorating carrier mobility (µH) and seriously limiting thermoelectric performance. Here, utilizing the cointroduction of Gd‐Cu2Te into n‐type PbSe as a paradigm, the zT could be greatly improved. The conduction band flattening caused by Gd doping can successfully compensate for the small Seebeck coefficient in n‐type PbSe, thus achieving extraordinary electrical performance. Further advanced electron microscopy and X‐ray absorption fine structure spectra directly demonstrate that most of the Cu forms nanoscale Cu2Se precipitates, especially a unique semi‐coherent interface between the PbSe matrix and the Cu2Se nanoprecipitate is observed for the first time. Such nanoprecipitate accompanied by the semi‐coherent interface not only ensures higher µH as an excellent charge transfer mediator but also collectively scatters the heat‐carrying phonons over a wide frequency range to obtain the ultralow κlat, resulting in the prominent improvement of the ratio µH/κlat. The present finding represents an important step forward in electron–phonon decoupling via constructing semi‐coherent nanostructure and interface engineering, which should be applicable for other thermoelectric materials. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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13. Achieving high quality factor and enhanced thermoelectric performance in polycrystalline SnS by Ag doping and Se alloying.
- Author
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He, Zhengmin, Zhu, Jianglong, Su, Wenjun, An, Xiang, Zhao, Canyang, Yuan, Wei, Lin, Liwei, and Ang, Ran
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QUALITY factor ,CARRIER density ,ELECTRONIC band structure ,THERMOELECTRIC materials ,SEEBECK coefficient ,SILVER ,SILVER alloys - Abstract
The polycrystalline SnS with a similar layered crystal structure and band structure to SnSe exhibits enormous commercial thermoelectric potential due to its lower cost and environmentally friendly characteristics. However, the wider bandgap of SnS leads to low carrier concentration and inferior electrical transport performance. The two-dimensional interlayer hinders carrier transport, leading to interesting and mysterious anisotropic thermoelectric properties. Herein, we reported the optimized electron–phonon transport in anisotropic polycrystalline SnS by Ag doping and Se alloying, realizing a high quality factor B by multiple strategies of optimizing carrier concentration, modifying band structure, and introducing various defects; further potential performance is predicted by the single parabolic band model. Specifically, Ag-doped SnS not only significantly increases the carrier concentration and weighted mobility μ
w in both directions but also induces multi-scale precipitates proven by the Debye–Callaway model to suppress phonon transport. Moreover, additional Se alloying optimizes the electronic band structure and increases the Seebeck coefficient, further improving μW and boosting the maximum power factor to ∼3.72 μW cm−1 K−2 at 873 K in the out-of-plane direction. Consequently, the synergistic optimization of carrier and phonon transport achieved a high B of 0.7 and a maximum zTmax of ∼0.8 at 873 K in Ag0.02 Sn0.98 S0.99 Se0.01 . Additionally, the high B predicted a high zTmax ∼1.5 based on optimized carrier transport characteristics, demonstrating the potential great-performance polycrystalline SnS. This work provides a promising avenue for optimizing the zT of polycrystalline SnS by transport engineering. [ABSTRACT FROM AUTHOR]- Published
- 2023
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14. Enhancing the Thermoelectric Properties via Modulation of Defects in P-Type MNiSn-Based (M = Hf, Zr, Ti) Half-Heusler Materials.
- Author
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Ai, Xin, Lei, Binghua, Cichocka, Magdalena O., Giebeler, Lars, Villoro, Ruben Bueno, Zhang, Siyuan, Scheu, Christina, Pérez, Nicolás, Zhang, Qihao, Sotnikov, Andrei, Singh, David J., Nielsch, Kornelius, and He, Ran
- Subjects
THERMOELECTRIC materials ,HEUSLER alloys ,PHONONS ,SEEBECK coefficient ,CARRIER density ,THERMAL conductivity - Abstract
The thermoelectric figure-of-merit (zT) of p-type MNiSn (M = Ti, Zr, or Hf) half-Heusler compounds is lower than their η-type counterparts due to the presence of a donor in-gap state caused by Ni occupying tetrahedral interstitials. While ZrNiSn and TiNiSn, have been extensively studied, HfNiSn remains unexplored. Herein, this study reports an improved thermoelectric property in p-type HfNi
1-x Cox Sn. By doping 5 at% Co at the Ni sites, the Seebeck coefficient becomes reaching a peak value exceeding 200 μV K-1 that breaks the record of previous reports. A maximum power factor of ≈2.2 mW m-1 K-2 at 973 K is achieved by optimizing the carrier concentration. The enhanced p-type transport is ascribed to the reduced content of Ni defects, supported by first principle calculations and diffraction pattern refinement. Concomitantly, Co doping also softens the lattice and scatters phonons, resulting in a minimum lattice thermal conductivity of ≈1.8 W m-1 K-1 . This leads to a peak zT of 0.55 at 973 K is realized, surpassing the best performing p-type MNiSn by 100%. This approach offers a new method to manipulate the intrinsic atomic disorder in half-Heusler materials, facilitating further optimization of their electronic and thermal properties. [ABSTRACT FROM AUTHOR]- Published
- 2023
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15. The thermoelectric performance in transition metal-doped PbS influenced by formation enthalpy.
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Gan, Lin, Zhang, Fujie, Wang, Minghui, Deng, Qian, Su, Wenjun, Zhang, Kun, and Ang, Ran
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HEAT of formation ,THERMOELECTRIC materials ,CARRIER density ,THERMOELECTRIC apparatus & appliances ,THERMOELECTRICITY ,TRANSITION metal oxides ,THERMOCHEMISTRY ,BOLTZMANN'S constant - Abstract
Transition metals have excellent valence electrical properties and unique electronic state distribution and are regarded as potential materials for improving thermoelectric performance. However, the impact of transition metals on thermoelectric materials is restricted to the solid solution limit and doping efficiency, reinforcing the shortcomings in systematic research. Here, thermoelectric properties of transition metal (Ti, V, Cr, Zr, Nb, Mo)-doped PbS are compared and analyzed systematically based on the formation enthalpy. The DFT calculation indicates that the doping (except Zr) leads to the bandgap expansion and the density of states distortion near the Fermi level, while the localization property of the latter results in an invalid resonance level. The formation enthalpy dominates the carrier concentration due to the opposite trend of carrier concentration and formation enthalpy. The formation enthalpy of Zr, Ti, and Nb doping is more negative than others, leading to the more significant optimization of carrier concentration. The Moss–Burstein effect promotes the bandgap expansion, leading to weaker bipolar effects for Zr, Ti, and Nb doping. Eventually, the thermoelectric performance for Ti, Zr, and Nb doping is superior to others at high temperature. The Hume-Rothery rule of the formation enthalpy supplementation is more suitable for the doping and alloying in thermoelectricity. Thermodynamic stability analysis based on the formation enthalpy contribute the PbS-based thermoelectric devices evaluation. The present finding demonstrates the significant effect of formation enthalpy on the thermoelectric properties of PbS and provides a useful avenue for the doping modification and thermodynamic stability analysis of other thermoelectric alloy materials. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
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16. Vacancy-mediated anomalous phononic and electronic transport in defective half-Heusler ZrNiBi.
- Author
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Ren, Wuyang, Xue, Wenhua, Guo, Shuping, He, Ran, Deng, Liangzi, Song, Shaowei, Sotnikov, Andrei, Nielsch, Kornelius, van den Brink, Jeroen, Gao, Guanhui, Chen, Shuo, Han, Yimo, Wu, Jiang, Chu, Ching-Wu, Wang, Zhiming, Wang, Yumei, and Ren, Zhifeng
- Subjects
ELECTRONIC band structure ,THERMOELECTRIC materials ,PHOTOELECTRICITY ,PHENOMENOLOGICAL theory (Physics) ,PHONON scattering ,THERMAL conductivity ,PHONONS - Abstract
Studies of vacancy-mediated anomalous transport properties have flourished in diverse fields since these properties endow solid materials with fascinating photoelectric, ferroelectric, and spin-electric behaviors. Although phononic and electronic transport underpin the physical origin of thermoelectrics, vacancy has only played a stereotyped role as a scattering center. Here we reveal the multifunctionality of vacancy in tailoring the transport properties of an emerging thermoelectric material, defective n-type ZrNiBi. The phonon kinetic process is mediated in both propagating velocity and relaxation time: vacancy-induced local soft bonds lower the phonon velocity while acoustic-optical phonon coupling, anisotropic vibrations, and point-defect scattering induced by vacancy shorten the relaxation time. Consequently, defective ZrNiBi exhibits the lowest lattice thermal conductivity among the half-Heusler family. In addition, a vacancy-induced flat band features prominently in its electronic band structure, which is not only desirable for electron-sufficient thermoelectric materials but also interesting for driving other novel physical phenomena. Finally, better thermoelectric performance is established in a ZrNiBi-based compound. Our findings not only demonstrate a promising thermoelectric material but also promote the fascinating vacancy-mediated anomalous transport properties for multidisciplinary explorations. Vacancy has only played a stereotyped role as a scattering center in thermoelectrics, and the boundaries of its versatility have not been tested. Here, authors reveal the multifunctionality of vacancy in tailoring the phononic and electronic transport in a defective half-Heusler ZrNiBi. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
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17. High-Throughput Screening of High-Performance Thermoelectric Materials with Gibbs Free Energy and Electronegativity.
- Author
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Xu, Guiying, Xin, Jiakai, Deng, Hao, Shi, Ran, Zhang, Guangbing, and Zou, Ping
- Subjects
GIBBS' free energy ,HIGH throughput screening (Drug development) ,THERMOELECTRIC materials ,ELECTRONEGATIVITY ,FREE material ,AB-initio calculations - Abstract
Thermoelectric (TE) materials are an important class of energy materials that can directly convert thermal energy into electrical energy. Screening high-performance thermoelectric materials and improving their TE properties are important goals of TE materials research. Based on the objective relationship among the molar Gibbs free energy (G
m ), the chemical potential, the Fermi level, the electronegativity (X) and the TE property of a material, a new method for screening TE materials with high throughput is proposed. This method requires no experiments and no first principle or Ab initio calculation. It only needs to find or calculate the molar Gibbs free energy and electronegativity of the material. Here, by calculating a variety of typical and atypical TE materials, it is found that the molar Gibbs free energy of Bi2 Te3 and Sb2 Te3 from 298 to 600 K (Gm = −130.20~−248.82 kJ/mol) and the electronegativity of Bi2 Te3 and Sb2 Te3 and PbTe (X = 1.80~2.21) can be used as criteria to judge the potential of materials to become high-performance TE materials. For good TE compounds, Gm and X are required to meet the corresponding standards at the same time. By taking Gm = −130.20~−248.82 kJ/mol and X = 1.80~2.21 as screening criteria for high performance TE materials, it is found that the Gm and X of all 15 typical TE materials and 9 widely studied TE materials meet the requirement very well, except for the X of Mg2 Si, and 64 pure substances are screened as potential TE materials from 102 atypical TE materials. In addition, with reference to their electronegativity, 44 pure substances are selected directly from a thermochemical data book as potential high-performance TE materials. A particular finding is that several carbides, such as Be2 C, CaC2 , BaC2 , SmC2 , TaC and NbC, may have certain TE properties. Because the Gm and X of pure substances can be easily found in thermochemical data books and calculated using the X of pure elements, respectively, the Gm and X of materials can be used as good high-throughput screening criteria for predicting TE properties. [ABSTRACT FROM AUTHOR]- Published
- 2023
- Full Text
- View/download PDF
18. Understanding the Temperature Dependence of the Seebeck Coefficient from First-Principles Band Structure Calculations for Organic Thermoelectric Materials
- Author
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Yufei Ge, Zhigang Shuai, Ran Liu, and Dong Wang
- Subjects
Temperature gradient ,Materials science ,Condensed matter physics ,Seebeck coefficient ,Thermoelectric effect ,General Chemistry ,Electric potential ,Electronic band structure ,Thermoelectric materials ,Boltzmann equation - Abstract
The Seebeck effect measures the electric potential built up in materials under a temperature gradient. For organic thermoelectric materials, the Seebeck coefficient shows more complicated temperatu...
- Published
- 2021
19. Boosting thermoelectrics by alloying Cu2Se in SnTe-CdTe compounds
- Author
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Yan Zhong, Ran Ang, Hangtian Liu, Fujie Zhang, Juan Li, Zhiyu Chen, and Jing Tang
- Subjects
Materials science ,Polymers and Plastics ,Dimensionless figure of merit ,Phonon ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,Lattice thermal conductivity ,symbols.namesake ,Thermoelectric effect ,Materials Chemistry ,business.industry ,Mechanical Engineering ,Fermi level ,Metals and Alloys ,Fermi energy ,021001 nanoscience & nanotechnology ,Thermoelectric materials ,Cadmium telluride photovoltaics ,0104 chemical sciences ,Mechanics of Materials ,Ceramics and Composites ,symbols ,Optoelectronics ,0210 nano-technology ,business - Abstract
The discovery of band convergence has opened an effective avenue for significantly enhancing thermoelectric performance of SnTe, while alloying CdTe in SnTe is evidenced efficient for improving the valley degeneracy. However, the thermoelectric transport properties are limited due to the low solubility of CdTe in SnTe (∼3%). Inspired by the improvement of dimensionless figure of merit zT in Cu or Se-doped SnTe, investigating the effect of Cu2Se on the electronic and phonon transport properties of SnTe-CdTe alloys is highly desired. Traditionally, improving the quality factor can trigger an increase of the potential of a compound for higher zT, which is of importance for design of thermoelectric materials. Here, alloyed 3% Cu2Se in SnTe-3%CdTe system enables an increased peak zT, which is attributed by the optimization of electronic performance (∼21 μW cm−1 K-2 at 800 K), as well as the decreased lattice thermal conductivity owing to the enhanced mass and strain fluctuations. More importantly, alloying Cu2Se not only improves the quality factor from ∼0.25 to ∼0.45, resulting in a higher maximum potential zT, but also effectively preserves the Fermi energy in a relative optimized level. The current findings demonstrate the role of Cu2Se for manipulating thermoelectrics in SnTe.
- Published
- 2021
20. Enhancing Near-Room-Temperature GeTe Thermoelectrics through In/Pb Co-doping
- Author
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Yan Zhong, Fujie Zhang, Juan Li, Xiaobo Tan, Qing Hu, Qian Deng, Shan He, and Ran Ang
- Subjects
Work (thermodynamics) ,Effective mass (solid-state physics) ,Materials science ,Condensed matter physics ,Phase (matter) ,Seebeck coefficient ,Thermoelectric effect ,Doping ,Density of states ,General Materials Science ,Thermoelectric materials - Abstract
The traditional thermoelectric material GeTe has drawn much attention recently because of the reported high thermoelectric performance of the rhombohedral phase in low-temperature ranges, where the split L and Σ band can be reconverged to have a small energy offset and thus high density of state effective mass according to the rhombohedral angle. In addition, In doping in GeTe is also reported to enhance the density of effective mass and therefore increase the Seebeck coefficient because of the induced resonant levels. In this work, In and Pb are doped in GeTe, and In doping leads to an increase in the rhombohedral angle and thus enhanced density of state effective mass in addition to the resonant effect. However, the improved Seebeck coefficient result from In doping is compensated for by a sharp reduction of Hall mobility, leading to no significant enhancement of electronic performance in the rhombohedral phase. By further Pb/Ge doping in the matrix Ge0.95In0.05Te for the optimization of carrier concentration and reduction of lattice thermal conductivity (as low as 0.7 W/mK), a zT as high as ∼1.2 at 550 K and average zT of ∼0.75 between 300 and 550 K are realized in this work, demonstrating GeTe as a promising candidate for near-room-temperature application.
- Published
- 2021
21. Enhancing the Thermoelectric Performance of GeSb 4 Te 7 Compounds via Alloying Se.
- Author
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Wang, Siyu, Xing, Tong, Wei, Tian-Ran, Zhang, Jiawei, Qiu, Pengfei, Xiao, Jie, Ren, Dudi, Shi, Xun, and Chen, Lidong
- Subjects
CARRIER density ,PHASE change materials ,SEEBECK coefficient ,THERMAL conductivity ,GALLIUM antimonide ,THERMOELECTRIC materials ,ALLOYS - Abstract
Ge-Sb-Te compounds (GST), the well-known phase-change materials, are considered to be promising thermoelectric (TE) materials due to their decent thermoelectric performance. While Ge
2 Sb2 Te5 and GeSb2 Te4 have been extensively studied, the TE performance of GeSb4 Te7 has not been well explored. Reducing the excessive carrier concentration is crucial to improving TE performance for GeSb4 Te7 . In this work, we synthesize a series of Se-alloyed GeSb4 Te7 compounds and systematically investigate their structures and transport properties. Raman analysis reveals that Se alloying introduces a new vibrational mode of GeSe2 , enhancing the interatomic interaction forces within the layers and leading to the reduction of carrier concentration. Additionally, Se alloying also increases the effective mass and thus improves the Seebeck coefficient of GeSb4 Te7 . The decrease in carrier concentration reduces the carrier thermal conductivity, depressing the total thermal conductivity. Finally, a maximum zT value of 0.77 and an average zT value of 0.48 (300–750 K) have been obtained in GeSb4 Te5.5 Se1.5 . This work investigates the Raman vibration modes and the TE performance in Se-alloyed GeSb4 Te7 sheddinglight on the performance optimization of other GST materials. [ABSTRACT FROM AUTHOR]- Published
- 2023
- Full Text
- View/download PDF
22. Size-Sensitive Thermoelectric Properties of Electrolyte-Based Nanofluidic Systems
- Author
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Yakang Jin, Zhigang Li, Shuang Luo, and Ran Tao
- Subjects
Materials science ,Graphene ,Enthalpy ,02 engineering and technology ,Electrolyte ,021001 nanoscience & nanotechnology ,Thermoelectric materials ,01 natural sciences ,Slip (ceramics) ,law.invention ,law ,Chemical physics ,visual_art ,Seebeck coefficient ,0103 physical sciences ,Thermoelectric effect ,visual_art.visual_art_medium ,Figure of merit ,General Materials Science ,Physical and Theoretical Chemistry ,010306 general physics ,0210 nano-technology - Abstract
In this work, we investigate the thermoelectric properties of aqueous KCl solutions confined in graphene nanochannels through molecular dynamics simulations. The channel height H ranges from 0.7 to 7.8 nm. It is found that the Seebeck coefficient, Se, and the figure of merit, ZT, of the KCl solution are highly sensitive to H when H is small. For the nanochannel of H = 1.0 nm, Se = 30.6 mV/K and ZT = 4.6 at room temperature, which are superior to most of the solid-state thermoelectric materials. The remarkable thermoelectric properties in small channels are attributed to the flow slip at the channel walls and the mean excess enthalpy density of the solution, which is mainly from the potential energy contribution. The molecular insight promotes the applications of nanofluidic devices for thermal energy harvesting.
- Published
- 2021
23. Efficient lanthanide Gd doping promoting the thermoelectric performance of Mg3Sb2-based materials
- Author
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Hexige Wuliji, Tian-Ran Wei, Xun Shi, Kunpeng Zhao, Jingdan Lei, Pengfei Qiu, Qing Xu, and Peng Li
- Subjects
Electron mobility ,Materials science ,Dopant ,Renewable Energy, Sustainability and the Environment ,business.industry ,Doping ,General Chemistry ,Thermoelectric materials ,Grain size ,Electronegativity ,Thermoelectric effect ,Optoelectronics ,General Materials Science ,Grain boundary ,business - Abstract
Mg3Sb2-based thermoelectric materials have recently received heightened attention due to their diverse merits of high band degeneracy, ultralow lattice thermal conductivity and high carrier mobility. However, the inherently low carrier concentration of pristine Mg3Sb2 seriously hinders the advancement of this material toward high thermoelectric performance. Therefore, searching for proper dopants to optimize the carrier concentration is one of the primary avenues to realize superior thermoelectric performance in Mg3Sb2-based materials. Herein, by considering the electronegativity difference Δχ and mass difference ΔM between the dopant and host elements, we theoretically and experimentally demonstrate lanthanide Gd as an effective dopant to tune the carrier concentration of Mg3Sb1.3Bi0.7 alloys. Owing to its high doping efficiency, a large carrier concentration up to 8.9 × 1019 cm−3 is realized through Gd doping, which is close to the optimal value. Moreover, the coarse grain size commendably mitigates the grain boundary effects and thus ensures high carrier mobility. Combining the greatly suppressed lattice thermal conductivity by point defect scattering, a maximum zT of 1.55 is achieved at 700 K in Mg3.065Sb1.3Bi0.7Gd0.015.
- Published
- 2021
24. Charting lattice thermal conductivity for inorganic crystals and discovering rare earth chalcogenides for thermoelectrics
- Author
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Sheng Gong, Tian Xie, Prashun Gorai, Jeffrey C. Grossman, Ran He, Taishan Zhu, and Kornelius Nielsch
- Subjects
Work (thermodynamics) ,Materials science ,Inorganic Crystal Structure Database ,Decision trees ,Materials informatics ,Thermal conductivity ,Chart ,Waste heat ,Rare earths ,Environmental Chemistry ,Inorganic materials ,Structural chemistry ,Thermo-Electric materials ,power generation ,Renewable Energy, Sustainability and the Environment ,Crystal structure ,Thermoelectric energy conversion ,Lattice thermal conductivity ,Thermoelectricity ,Thermoelectric materials ,Pollution ,Engineering physics ,Graph neural networks ,inorganic compound ,rare earth element ,Thermoelectric generator ,Nuclear Energy and Engineering ,Inorganic crystal structure database ,lattice dynamics ,Chalcogenides - Abstract
Thermoelectric power generation represents a promising approach to utilize waste heat. The most effective thermoelectric materials exhibit low thermal conductivity κ. However, less than 5% out of about 105 synthesized inorganic materials are documented with their κ values, while for the remaining 95% κ values are missing and challenging to predict. In this work, by combining graph neural networks and random forest approaches, we predict the thermal conductivity of all known inorganic materials in the Inorganic Crystal Structure Database, and chart the structural chemistry of κ into extended van-Arkel triangles. Together with the newly developed κ map and our theoretical tool, we identify rare-earth chalcogenides as promising candidates, of which we measured ZT exceeding 1.0. We note that the κ chart can be further explored, and our computational and analytical tools are applicable generally for materials informatics.
- Published
- 2021
25. Grain Boundary Phases in NbFeSb Half‐Heusler Alloys: A New Avenue to Tune Transport Properties of Thermoelectric Materials.
- Author
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Bueno Villoro, Ruben, Zavanelli, Duncan, Jung, Chanwon, Mattlat, Dominique Alexander, Hatami Naderloo, Raana, Pérez, Nicolás, Nielsch, Kornelius, Snyder, Gerald Jeffrey, Scheu, Christina, He, Ran, and Zhang, Siyuan
- Subjects
CRYSTAL grain boundaries ,ATOM-probe tomography ,SCANNING transmission electron microscopy ,THERMOELECTRIC materials ,PHONON scattering ,MAGNETOTELLURICS ,ELECTRIC conductivity ,PHASE transitions - Abstract
Many thermoelectric materials benefit from complex microstructures. Grain boundaries (GBs) in nanocrystalline thermoelectrics cause desirable reduction in the thermal conductivity by scattering phonons, but often lead to unwanted loss in the electrical conductivity by scattering charge carriers. Therefore, modifying GBs to suppress their electrical resistivity plays a pivotal role in the enhancement of thermoelectric performance, zT. In this work, different characteristics of GB phases in Ti‐doped NbFeSb half‐Heusler compounds are revealed using a combination of scanning transmission electron microscopy and atom probe tomography. The GB phases adopt a hexagonal close‐packed lattice, which is structurally distinct from the half‐Heusler grains. Enrichment of Fe is found at GBs in Nb0.95Ti0.05FeSb, but accumulation of Ti dopants at GBs in Nb0.80Ti0.20FeSb, correlating to the bad and good electrical conductivity of the respective GBs. Such resistive to conductive GB phase transition opens up new design space to decouple the intertwined electronic and phononic transport in thermoelectric materials. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
26. Advancing thermoelectrics by suppressing deep-level defects in Pb-doped AgCrSe2 alloys.
- Author
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Wang, Yadong, Zhang, Fujie, Rao, Xuri, Feng, Haoran, Lin, Liwei, Ren, Ding, Liu, Bo, and Ang, Ran
- Subjects
CARRIER density ,THERMAL conductivity ,PHONON scattering ,THERMOELECTRIC materials ,POINT defects ,ALLOYS ,SILVER alloys ,SILVER - Abstract
AgCrSe
2 -based compounds have attracted much attention as an environmentally friendly thermoelectric material in recent years due to the intriguing liquid-like properties. However, the ultra-low carrier concentration and the high AgCr deep-level defects limit the overall thermoelectric performance. Here, we successfully introduced Pb into Ag-deficient Ag0.97 CrSe2 alloys to tune the carrier concentration across a broad temperature range. The Pb2+ as an acceptor dopant preferentially occupies Cr sites, boosting the hole carrier concentration to 1.77 × 1019 cm−3 at room temperature. Furthermore, the Pb strongly inhibits the creation of intrinsic AgCr defects, weakens the increased thermal excited ionization with the increasing temperature and slowed the rising trend of the carrier concentration. The designed carrier concentration matches the theoretically predicted optimized one over the entire temperature range, leading to a remarkable enhancement in power factor, especially the maximum power factor of ∼ 500 μW⋅m−1 ⋅K−2 at 750 K is superior to most previous results. Additionally, the abundant point defects promote phonon scattering, thus reducing the lattice thermal conductivity. As a result, the maximum figure of merit zT (∼ 0.51 at 750 K) is achieved in Ag0.97 Cr0.995 Pb0.005 Se2 . This work confirms the feasibility of manipulating deep-level defects to achieve temperature-dependent optimal carrier concentration and provides a valuable guidance for other thermoelectric materials. [ABSTRACT FROM AUTHOR]- Published
- 2023
- Full Text
- View/download PDF
27. Synergistic band modulation and precipitates: Achieving high quality factor in SnTe.
- Author
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He, Shan, Zhang, Fujie, Li, Ruiheng, Gan, Lin, Tan, Xiaobo, Zhu, Jianglong, and Ang, Ran
- Subjects
QUALITY factor ,THERMOELECTRIC materials ,SEEBECK coefficient ,FERMI level ,CARRIER density ,PHONON scattering - Abstract
Breaking the thermoelectric figure of merit zT barrier of SnTe enables it to become a promising alternative to PbTe; however, the inferior and strongly coupled physicochemical properties of pristine SnTe severely restrict the efficient optimization. Herein, we doped trivalent Sb in SnTe and incorporated SnS particles to achieve high quality factor B through a two-step optimization strategy of tuning the valence band structure and intercalating heterostructural precipitates, and well predicted the potential prospects. The high solubility limit of Sb not only reduced the carrier concentration n
H but also significantly optimized the valence band structure and improved the Seebeck coefficient, thereby enhancing the weight mobility μw in the all-temperature region. Furthermore, the additional SnS, which tends to exist as precipitates with different micrometer-scale sizes, enhanced low-medium-frequency phonon scattering in a wider frequency range except for point defects scattering, suppressing the lattice thermal conductivity to 0.55 W m−1 K−1 . As a result of this synergistic effect, a high B-factor of ∼0.82 greater than triple pure SnTe was obtained in Sn0.91 Sb0.09 Te-10%SnS, with an enhanced zT of ∼1.15 at 850 K. More importantly, the high B-factor accurately predicted an excellent zT value of ∼1.65 at the optimal Fermi level, which highlights the great potential of Sn1- x Sbx Te-y%SnS-based materials. This work provides an effective route for stepwise optimization of electrical and thermal performance from the B-factor perspective and has guiding significance for other thermoelectric materials. [ABSTRACT FROM AUTHOR]- Published
- 2023
- Full Text
- View/download PDF
28. Reducing Effective Mass for Advancing Thermoelectrics in Sb/Bi-Doped AgCrSe2 Compounds
- Author
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Ming Jing Tang, Hangtian Liu, Yan Zhong, Bin Kang, Fujie Zhang, Xuming Guo, Zhiyu Chen, and Ran Ang
- Subjects
010302 applied physics ,Materials science ,business.industry ,Doping ,02 engineering and technology ,Power factor ,Electron ,021001 nanoscience & nanotechnology ,Thermal conduction ,Thermoelectric materials ,01 natural sciences ,Effective mass (solid-state physics) ,0103 physical sciences ,Thermoelectric effect ,Optoelectronics ,Figure of merit ,General Materials Science ,0210 nano-technology ,business - Abstract
Liquid-like materials have attracted increasing attention, owing to their phonon-liquid electron-crystal feature. As a typical representative, the superionic conductor AgCrSe2 is regarded as a promising thermoelectric for its intrinsic ultralow lattice thermal conductivity. The primary challenge for achieving high thermoelectric performance is to enhance the inferior electronic performance in AgCrSe2 compounds. Thus, it is very significant to manipulate band effective mass to achieve a higher power factor. In this work, the Sb/Bi elements are doped at Cr sites in Ag0.97CrSe2, i.e., Ag0.97Cr1-x(Sb/Bi)xSe2, aiming at producing a better overlap of electron orbits between different atoms for sharpening the valence band and decreasing the effective mass. In comparison to pristine AgCrSe2, a considerable improvement (>50%) in the power factor (∼387 μW m-1 K-2 at 750 K) is realized upon 3% Sb doping. The single parabolic band model clarifies that the decreased effective mass and optimized carrier concentration contribute to the enhanced electronic property. Furthermore, an ultralow lattice thermal conductivity (∼0.2 W m-1 K-1) is well-maintained for the sample with 3% Sb doping as a result of the nearly unchanged superionic conduction. Eventually, a high peak figure of merit zT (∼0.7 at 750 K) is obtained in Ag0.97Cr0.97Sb0.03Se2. The current finding provides an excellent avenue for advancing thermoelectrics in AgCrSe2 materials.
- Published
- 2020
29. Conformal organic–inorganic semiconductor composites for flexible thermoelectrics
- Author
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Pengfei Qiu, Qing Xu, Xun Shi, Lidong Chen, Jian He, Chenxi Zhu, Qin Yao, Sanyin Qu, Chen Ming, and Tian-Ran Wei
- Subjects
Renewable Energy, Sustainability and the Environment ,Chemistry ,business.industry ,Carbon nanotube ,Thermoelectric materials ,Pollution ,Flexible electronics ,law.invention ,Thermoelectric generator ,Semiconductor ,Nuclear Energy and Engineering ,law ,Seebeck coefficient ,Thermoelectric effect ,Environmental Chemistry ,Electronics ,Composite material ,business - Abstract
The development of flexible organic–inorganic thermoelectric composites constitutes a promising material approach toward harvesting heat from the human body or environment to power wearable electronics. To this end, compositing one-dimensional inorganic materials, such as carbon nanotubes or metal nanowires, with organic polymers has demonstrated efficacy but also drawbacks: e.g., the Seebeck coefficient of an inorganic constituent is too low to meet the onset voltage requirement of electronics, and it is hard to attain coherent interfaces between the inorganic and organic constituents. Here, we proposed a dimensionality/morphology matching strategy and conducted a proof-of-principle study on (PVDF)/Ta4SiTe4 organic–inorganic composites. A record high normalized maximum power density of 0.13 W m−1 at a temperature difference of 35.5 K was obtained in prototype flexible thermoelectric modules made of (PVDF)/Ta4SiTe4 composites. This study attests to the efficacy of the dimensionality/morphology matching strategy and the potential of using such conformal semiconducting organic–inorganic composites in wearable electronics.
- Published
- 2020
30. Discovery of high-performance thermoelectric copper chalcogenide using modified diffusion-couple high-throughput synthesis and automated histogram analysis technique
- Author
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Pengfei Qiu, Tingting Deng, Jiong Yang, Qingfeng Song, Madison K. Brod, Yuri Grin, Xun Shi, Lidong Chen, G. Jeffrey Snyder, Tian-Ran Wei, Ye Sheng, Igor Veremchuk, and Tong Xing
- Subjects
Materials science ,Thermoelectric cooling ,Renewable Energy, Sustainability and the Environment ,Chalcogenide ,business.industry ,Band gap ,Doping ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Thermoelectric materials ,01 natural sciences ,Pollution ,0104 chemical sciences ,Characterization (materials science) ,chemistry.chemical_compound ,Nuclear Energy and Engineering ,chemistry ,Thermoelectric effect ,Environmental Chemistry ,Optoelectronics ,0210 nano-technology ,business ,Ternary operation - Abstract
Discovery of novel high-performance materials with earth-abundant and environmentally friendly elements is a key task for civil applications based on advanced thermoelectric technology. Advancements in this area are greatly limited by the traditional trial-and-error method, which is both time-consuming and expensive. The materials genome initiative can provide a powerful strategy to screen for potential novel materials using high-throughput calculations, materials characterization, and synthesis. In this study, we developed a modified diffusion-couple high-throughput synthesis method and an automated histogram analysis technique to quickly screen high-performance copper chalcogenide thermoelectric materials, which has been well demonstrated in the ternary Cu–Sn–S compounds. A new copper chalcogenide with the composition of Cu7Sn3S10 was discovered. Studies on crystal structure, band gap, and electrical and thermal transport properties were performed to show that it is a promising thermoelectric material with ultralow lattice thermal conductivity, moderate band gap, and decent electrical conductivity. Via Cl doping, the thermoelectric dimensionless figure of merit zT reaches 0.8 at 750 K, being among the highest values reported in Cu–Sn–S ternary materials. The modified diffusion-couple high-throughput synthesis method and automated histogram analysis technique developed in this study also shed light on the development of other advanced thermoelectric and functional materials.
- Published
- 2020
31. Routes for advancing SnTe thermoelectrics
- Author
-
Zhiyu Chen, Qing Shi, Mingjing Tang, Ran Ang, Xuming Guo, and Fujie Zhang
- Subjects
Materials science ,Renewable Energy, Sustainability and the Environment ,Phonon ,business.industry ,Pb toxicity ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Thermoelectric energy conversion ,Thermoelectric materials ,01 natural sciences ,Engineering physics ,0104 chemical sciences ,Lattice thermal conductivity ,Semiconductor ,Thermoelectric effect ,Valence band ,General Materials Science ,0210 nano-technology ,business - Abstract
Conventional PbTe-based semiconductors have been leading the developments in the thermoelectrics community due to their rich capabilities in optimizing the electronic and phonon transport properties. However, growing environmental concerns related to Pb toxicity is guiding thermoelectrics research toward the lead-free route. As an alternative analog of PbTe, SnTe has recently attracted increasing research interest for thermoelectric energy conversion. The key challenges for enhancing the thermoelectric performance of SnTe to be comparable with that of p-type PbTe include decreases in the carrier concentration, energy offset between the light valence band (L band) and heavy valence band (Σ band), and lattice thermal conductivity. In this review, the recent progresses made in SnTe alloys are first outlined. Based on the insights gained into the intrinsic nonstoichiometry as well as the electronic and phonon transport properties of SnTe materials, fundamental and successful strategies focusing on confronting the challenges faced by figure-of-merit zT enhancement in SnTe are discussed and highlighted, aiming at providing a straightforward overview on the underlying physics of these effective strategies. Eventually, future challenges and outlook are summarized for boosting advancements in environment-friendly SnTe thermoelectric materials.
- Published
- 2020
32. Cu2Se-Based liquid-like thermoelectric materials: looking back and stepping forward
- Author
-
Pengfei Qiu, Tian-Ran Wei, Xun Shi, Kunpeng Zhao, Lidong Chen, and Zixun Zhang
- Subjects
Phase transition ,Materials science ,Nuclear Energy and Engineering ,Renewable Energy, Sustainability and the Environment ,Thermoelectric effect ,Environmental Chemistry ,Thermoelectric materials ,Pollution ,Engineering physics - Abstract
High-performance liquid-like thermoelectrics have attracted global renewed attention since the paradigm of ‘phonon-liquid electron-crystal’ was proposed in 2012. As one of the most typical liquid-like thermoelectric materials, Cu2Se-based compounds have been widely studied and their thermoelectric figure of merits have continuously increased up to >2.0. Herein, a comprehensive overview is presented on the recent progress and future challenges for Cu2Se-based thermoelectric materials. First, the basic properties of Cu2Se, such as the complex crystal structures, unique liquid-like behavior, and anomalous critical phenomenon during phase transition are presented. Next, some common synthesis recipes are concisely outlined and the impact on the thermoelectric properties is intercompared. The effective strategies for improving the thermoelectric performance are then summarized, with some typical studies highlighted. Furthermore, the utmost concerned stability issues, in particular Cu ion migration, are discussed followed by the latest progress on Cu2Se-based thermoelectric devices. Finally, the challenges and outlook toward further development of Cu2Se-based materials, devices, and applications are provided.
- Published
- 2020
33. Phase-modulated mechanical and thermoelectric properties of Ag2S1-x Tex ductile semiconductors
- Author
-
Tian-Ran Wei, Jiong Yang, Zhen Zhang, Shiqi Yang, Lidong Chen, Liming Peng, Pengfei Qiu, and Xun Shi
- Subjects
Work (thermodynamics) ,Phase transition ,Materials science ,Condensed matter physics ,business.industry ,Metals and Alloys ,Mechanical properties ,Crystal structure ,Plasticity ,Condensed Matter Physics ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Semiconductor ,Phase (matter) ,Thermoelectric effect ,Transport properties ,Thermoelectric materials ,business ,Ag2S-Ag2Te ductile semiconductors ,Den kondenserade materiens fysik ,Monoclinic crystal system - Abstract
By virtue of the excellent plasticity and tunable transport properties, Ag2S-based materials demonstrate an intriguing prospect for flexible or hetero-shaped thermoelectric applications. Among them, Ag2S1-xTex exhibits rich and interesting variations in crystal structure, mechanical and thermoelectric transport properties. However, Te alloying obviously introduces extremely large order-disorder distributions of cations and anions, leading to quite complicated crystal structures and thermoelectric properties. Detailed composition-structure-performance correlation of Ag2S1-xTex still remains to be established. In this work, we designed and prepared a series of Ag2S1-xTex (x = 0∼0.3) materials with low Te content. We discovered that the monoclinic-to-cubic phase transition occurs around x = 0.16 at room temperature. Te alloying plays a similar role as heating in facilitating this monoclinic-to-cubic phase transition, which is analyzed based on the thermodynamic principles. Compared with the monoclinic counterparts, the cubic-structured phases are more ductile and softer in mechanical properties. In addition, the cubic phases show a degenerately semiconducting behavior with higher thermoelectric performance. A maximum zT = 0.8 at 600 K and bending strain larger than 20% at room temperature were obtained in Ag2S0.7Te0.3. This work provides a useful guidance for designing Ag2S-based alloys with enhanced plasticity and high thermoelectric performance.
- Published
- 2022
34. Texturization-Induced In-Plane High-Performance Thermoelectrics and Inapplicability of the Debye Model to Out-of-Plane Lattice Thermal Conductivity in Misfit-Layered Chalcogenides
- Author
-
Jing Tang, Cong Yin, Yanzhong Pei, Ran Ang, Qing Hu, and Hangtian Liu
- Subjects
Electron mobility ,Materials science ,Condensed matter physics ,02 engineering and technology ,Power factor ,021001 nanoscience & nanotechnology ,Thermoelectric materials ,01 natural sciences ,Crystallographic defect ,Transverse plane ,symbols.namesake ,0103 physical sciences ,Thermoelectric effect ,symbols ,General Materials Science ,Texture (crystalline) ,010306 general physics ,0210 nano-technology ,Debye model - Abstract
Texturization tuning is of crucial significance for designing and developing high-performance thermoelectric materials and devices. Here, we report for the first time that a strong texturization effect induces an in-plane high-performance thermoelectric and an out-of-plane low lattice thermal conductivity in Sb-substituted misfit-layered (SnS)1.2(TiS2)2 alloys. In the in-plane direction, the oriented texture promotes a high carrier mobility, contributing to the maximization of the power factor (∼0.90 mW K-2 m-1). Moreover, the in-plane lattice thermal conductivity dramatically reduces deriving from the point defects due to the Sb substitution and weakened transverse sound velocity owing to the softening of bonding, ultimately leading to one of the highest thermoelectric performances ever reported among misfit-layered chalcogenides. In particular, in the out-of-plane direction, the texturization triggers the lowest lattice thermal conductivity (∼0.39 W K-1 m-1), exceeding the theoretical limit of the Debye-Cahill model, which provides a precious opportunity to investigate this real Sb-substituted (SnS)1.2(TiS2)2 material. The present finding in misfit-layered chalcogenides provides a novel strategy for manipulating thermoelectrics via texturization engineering.
- Published
- 2019
35. Multi-scale study of the deformation mechanisms of thermoelectric p-type half-Heusler Hf0.44Zr0.44Ti0.12CoSb0.8Sn0.2.
- Author
-
Aumand, Matthieu, Amiard, Guillaume, He, Ran, Ren, Zhifeng F., White, Ken W., and Thilly, Ludovic
- Subjects
THERMOELECTRIC materials ,DEFORMATIONS (Mechanics) ,HEUSLER alloys ,ELASTIC modulus ,MATERIAL plasticity - Abstract
Increasing the figure of merit ZT of thermoelectric (TE) alloys is a challenge that is currently attempted through various metallurgy methods, including nanostructuring and dislocation engineering. Microstructures with such a level of complexity raise questions about the mechanical reliability of these new materials. Indeed, despite the values of hardness and elastic modulus known for the clear majority of TE materials, the data on deformation mechanisms are still rare. Focusing on the nanostructured p-type half-Heusler Hf
0.44 Zr0.44 Ti0.12 CoSb0.8 Sn0.2 , our multi-scale study aims to analyze the deformation mechanisms. Experiments conducted at macro-, meso-, and micro-scale are designed to trigger and assess plasticity mechanisms. Compression testing on bulk samples subject to a confining pressure environment and temperature leads to an exclusive brittle failure. The mixed-mode failure mechanisms involve switching between intra- and inter-granular crack propagation, depending on the grain size met by the crack tip. Cube-corner nanoindentation at meso-scale generates cracks and enables fracture toughness estimation, while TEM analysis of the crack tip area confirms no dislocation activity and 3D-Electron Back Scattered Diffraction technique confirms the mixed crack propagation behavior. At micro-scale, micro-pillar compression stress-strain curves and failure mechanisms are comparable with bulk samples testing analysis. These results can be used to provide design guidelines for more crack-resistant TE alloys. [ABSTRACT FROM AUTHOR]- Published
- 2018
- Full Text
- View/download PDF
36. Annealing engineering induced high thermoelectric performance in Yb-filled CoSb3 skutterudites.
- Author
-
Feng, Haoran, Deng, Qian, Zhong, Yan, Rao, Xuri, Wang, Yadong, Zhu, Jianglong, Zhang, Fujie, and Ang, Ran
- Subjects
THERMOELECTRIC generators ,THERMOELECTRIC apparatus & appliances ,THERMOELECTRIC materials ,ANNEALING of metals ,PHONON scattering ,THERMAL conductivity ,ENERGY conversion ,CRYSTAL grain boundaries - Abstract
• It was proved that annealing engineering significantly affected microstructure and thermoelectrical properties of Yb-filled CoSb 3. • More cage-filled Yb atoms can effectively optimize the carrier concentration and flatten conduction band so as to maximize the electrical transport properties of CoSb 3 skutterudites. • The quality factor is enhanced from ∼0.29 to ∼0.56 due to the improved density-of-state effective mass and suppressed lattice thermal conductivity at 823 K, resulting in a superior ZT ∼1.33. The great pressure of energy shortage has made CoSb 3 materials with excellent mechanical stability in the mid-temperature region favored for the integration of thermoelectric devices. However, their excessive lattice thermal conductivity and poor Seebeck coefficient lead to low energy conversion efficiency. Filling Yb into the lattice void to optimize the band structure and regulate the chemical potential is an indispensable means for improving the thermoelectric properties of CoSb 3 -based materials, while the phase structure and thermoelectric properties vary with the preparation process. This motivates the current work to focus on the influence of annealing temperature on the microstructure and thermoelectric properties of Yb-filled CoSb 3. Experimental analysis and theoretical model elucidated that an increase in annealing temperature can optimize the Yb filling fraction, which simultaneously manipulates the band structure as well as chemical potential, resulting in an excellent electrical property. Furthermore, the phase and microstructure characterization clarify that the annealing temperature can effectively affect the grain size. The complex grain boundary induced by grain refinement, more filled Yb atoms and precipitates strongly scatter wide-frequency phonons, significantly suppressing the lattice thermal conductivity. As a result, a superior dimensionless figure of merit (ZT) value of ∼1.33 at 823 K and an average ZT ave of ∼0.9 (323–823 K) were achieved in the Yb 0.4 Co 4 Sb 12 sample annealed at 923 K, and the calculated conversion efficiency could reach ∼13%. This work provides a unique paradigm to improve thermoelectrics in the filled CoSb 3 -based skutterudites by annealing engineering. [Display omitted] [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
37. Enhancing Thermoelectrics for Small-Bandwidth n-Type PbTe-MnTe Alloys via Balancing Compromise
- Author
-
Yan Zhong, Hangtian Liu, Lin Gan, Fangling Lv, Qian Deng, and Ran Ang
- Subjects
Electron mobility ,Work (thermodynamics) ,Materials science ,Phonon ,Scattering ,business.industry ,chemistry.chemical_element ,Atmospheric temperature range ,Thermoelectric materials ,Copper ,chemistry ,Thermoelectric effect ,Optoelectronics ,General Materials Science ,business - Abstract
Small-bandwidth n-type PbTe-MnTe alloys effectively modify the valley shape, while it also inevitably aggravates the deterioration of carrier mobility as nonpolar phonons dominate the scattering. It is found that a trace amount of Cu doping can alleviate the compromises among thermoelectric parameters, thereby significantly optimizing the electrical-transport performance near room temperature of n-type PbTe-MnTe alloys. The single-Kane model reveals that the physical origin of performance improvement lies in the carrier mobility enhancement and self-optimization of carrier concentration. The Debye-Callaway model further quantifies the contribution of copper defect scattering to the lattice thermal conductivity. Notably, the high thermoelectric quality factor obtained in this work rationalizes their superior properties and reveals immense potential for achieving higher zT. Herein, an extremely high zT of ∼0.52 at room temperature and a maximum zTmax of ∼1.2 at 823 K are achieved in 0.3% Cu-intercalated n-type PbTe-MnTe. The mechanism in balancing compromise elaborated in principle contributes to an improvement of thermoelectric properties of the n-type PbTe alloys in a broad temperature range.
- Published
- 2021
38. Optimized carrier concentration and enhanced thermoelectric properties in GeSb4-xBixTe7 materials.
- Author
-
Wang, Siyu, Xing, Tong, Hu, Ping, Wei, Tian-Ran, Bai, Xudong, Qiu, Pengfei, Shi, Xun, and Chen, Lidong
- Subjects
CARRIER density ,THERMOELECTRIC materials ,SEEBECK coefficient ,THERMAL conductivity ,SOLID solutions ,THERMAL properties - Abstract
As the pseudo-binary alloys between GeTe and Sb
2 Te3 , GeSbTe-based compounds are promising thermoelectric materials. Although Ge2 Sb2 Te5 and GeSb2 Te4 have widely been studied, the thermoelectric properties of GeSb4 Te7 have not been well understood yet. In this work, we design a series of GeSb4- x Bix Te7 solid solutions and systematically study the variation in the crystal structure, electrical, and thermal transport properties. Alloying Bi effectively reduces the carrier concentration and, thus, enhances the Seebeck coefficient. Meanwhile, the thermal conductivity is greatly reduced via large mass fluctuations. A maximum zT of 0.69 at 550 K and an average zT value of 0.52 between 300 and 700 K have been achieved for GeSb1.5 Bi2.5 Te7 . These findings will promote the understanding and development of GeSbTe-based thermoelectric materials. [ABSTRACT FROM AUTHOR]- Published
- 2022
- Full Text
- View/download PDF
39. Thermoelectric materials with crystal-amorphicity duality induced by large atomic size mismatch
- Author
-
Jian He, Zhicheng Jin, Bo B. Iversen, Espen Eikeland, Pengfei Qiu, Lidong Chen, Tian-Ran Wei, Wujie Qiu, Dongsheng He, Jiaqing He, Qingfeng Song, Xun Shi, Jianjun Liu, and Kunpeng Zhao
- Subjects
Materials science ,THERMAL-CONDUCTIVITY ,Duality (optimization) ,Context (language use) ,02 engineering and technology ,Crystal structure ,010402 general chemistry ,sublattice ,thermoelectric ,01 natural sciences ,Crystal ,crystal-amorphicity duality ,Thermoelectric effect ,thermal conductivity ,CHALCOGENIDES ,Condensed matter physics ,PERFORMANCE ,021001 nanoscience & nanotechnology ,Thermoelectric materials ,TRANSPORT ,0104 chemical sciences ,General Energy ,Atomic radius ,atomic size mismatch ,Orthorhombic crystal system ,PHASE-TRANSITIONS ,0210 nano-technology - Abstract
Discovering novel materials and attaining higher performance are the eternal pursuit of thermoelectric materials research. Here, we report a material series, (Cu1−xAgx)2(Te1−ySy) (0.16 ≤ x ≤ 0.24, 0.16 ≤ y ≤ 0.24), which adopts a complex orthorhombic structure differing from any known crystal structure of (Cu/Ag)2(S/Te). This material series is featured by the crystal-amorphicity duality induced by the large anionic size mismatch: a crystalline sublattice of highly size-mismatched anions Te/S coexists with an amorphous-like sublattice of cations Cu/Ag. In the context of structure-property correlation, the crystal-amorphicity duality gave rise to not only interesting electrical properties but also exceptionally low lattice thermal conductivities from 300 to 1,000 K. A state-of-the-art figure of merit zT of 2.0 is obtained in the x = y = 0.22 sample at 1,000 K. These results give insights into crystal-amorphicity duality as a paradigm-shifting materials design approach to develop high-performance thermoelectric materials.
- Published
- 2021
40. Extraordinary Role of Bi for Improving Thermoelectrics in Low-Solubility SnTe–CdTe Alloys
- Author
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Jing Tang, Fen Xiong, Yue Chen, Zhiyu Chen, Xuming Guo, Wen Li, and Ran Ang
- Subjects
Materials science ,Condensed matter physics ,Doping ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Thermoelectric materials ,01 natural sciences ,Cadmium telluride photovoltaics ,0104 chemical sciences ,Lattice thermal conductivity ,Thermoelectric figure of merit ,Thermoelectric effect ,Valence band ,General Materials Science ,Solubility ,0210 nano-technology - Abstract
As an environment-friendly alternative to traditional PbTe, many attempts have recently been made to improve thermoelectric SnTe. Effective strategies are mainly focused on valence band convergence, nanostructuring, interstitial defects, and alloying solubility. In particular, alloying SnTe with CdTe/GeTe triggers an inherent decline of valence band offset effectively owing to a high solubility of ∼20% of CdTe. However, to what level an additional element doping in low-solubility SnTe-CdTe alloys can play a role in enhancing the thermoelectric performance still remains a mystery. Here, a new strategy is shown that unexpected Bi doping, by alloying with only ∼3% CdTe, induces a significant enhancement of the thermoelectric figure of merit ZT to be ∼240% (ZT up to ∼1.3) at 838 K, which is mainly determined by the dramatically reduced lattice thermal conductivity above 800 K deriving from the exotic Bi doping and Cu-interstitial defects. More interestingly, combining experimental and theoretical evidences, the Bi-doping-driven band convergence is also beneficial to the improvement of thermoelectric performance below 800 K. The present findings demonstrate the extraordinary role of Bi for advancing the thermoelectric performance in SnTe alloys.
- Published
- 2019
41. Thermoelectric properties of p-type MnSe
- Author
-
Binqiang Zhou, Bo Chen, Hongxia Liu, Ran Ang, Zhonglin Bu, Wen Li, Liangtao Zheng, and Juan Li
- Subjects
Materials science ,Condensed matter physics ,Phonon scattering ,Scattering ,Mechanical Engineering ,Doping ,Metals and Alloys ,Wide-bandgap semiconductor ,chemistry.chemical_element ,02 engineering and technology ,Manganese ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Thermoelectric materials ,01 natural sciences ,0104 chemical sciences ,chemistry.chemical_compound ,chemistry ,Mechanics of Materials ,Selenide ,Thermoelectric effect ,Materials Chemistry ,0210 nano-technology - Abstract
Semiconducting manganese selenide (MnSe), crystalizing in a cubic structure with a wide band gap, is focused on in this work for its potential as an ecofriendly thermoelectric material. Pristine MnSe exhibits a low carrier concentration of ∼1.3 × 1017 cm−3 at room temperature, which can be dramatically increased to ∼2.6 × 1021 cm−3 primarily resulting from the Mn-vacancy introduced by Na-doping at Mn site. The broad range of carrier concentration not only enables a reliable prediction of the electrical transport properties using a single parabolic band (SPB) model with the acoustic scattering, but also provides a well understanding of its underlying material physics. Such a doping and the simultaneously induced Mn-vacancies provide additional phonon scattering, leading to a reduced lattice thermal conductivity of ∼1.2 W/m-K at high temperatures.
- Published
- 2019
42. Flexible thermoelectrics: from silver chalcogenides to full-inorganic devices
- Author
-
Pengfei Qiu, Chen Ming, Shiqi Yang, Qingfeng Song, Jian He, Yi-Yang Sun, Dudi Ren, Tuo Wang, Hongyi Chen, Xun Shi, Kunpeng Zhao, Lidong Chen, Tian-Ran Wei, and Jiasheng Liang
- Subjects
Flexibility (engineering) ,Electrical mobility ,Materials science ,Renewable Energy, Sustainability and the Environment ,business.industry ,Orders of magnitude (temperature) ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Thermoelectric materials ,7. Clean energy ,01 natural sciences ,Pollution ,Engineering physics ,Flexible electronics ,0104 chemical sciences ,Semiconductor ,Nuclear Energy and Engineering ,Environmental Chemistry ,Figure of merit ,Power output ,0210 nano-technology ,business - Abstract
Flexible thermoelectrics is a synergy of flexible electronics and thermoelectric energy conversion. To date, state-of-the-art thermoelectrics is based on inorganic semiconductors that afford high electron mobility but lack in mechanical flexibility. By contrast, organic materials are amply flexible but low in electrical mobility and power output; the inorganic–organic hybrid design is a viable material-level option but has critical device-level issues for practical application. Here, we reported high intrinsic flexibility and state-of-the-art figures of merit (up to 0.44 at 300 K and 0.63 at 450 K) in Ag2S-based inorganic materials, opening a new avenue of flexible thermoelectrics. In the flexible full-inorganic devices made of such Ag2S-based materials, high electrical mobility yielded a normalized maximum power density up to 0.08 W m−1 under a temperature difference of 20 K near room temperature, orders of magnitude higher than organic devices and organic–inorganic hybrid devices. These results promised an emerging paradigm and market of wearable thermoelectrics.
- Published
- 2019
43. Enhanced thermoelectric performance of two dimensional MS2 (M = Mo, W) through phase engineering
- Author
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Davide Donadio, Bin Ouyang, Tian-Ran Wei, Shiyun Xiong, Shunda Chen, and Yuhang Jing
- Subjects
Phase transition ,Materials science ,Phonon ,Band gap ,Thermoelectric ,Metals and Alloys ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Thermoelectric materials ,01 natural sciences ,Engineering physics ,Transition metal dichalcogenides ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Phase engineering ,0103 physical sciences ,Thermoelectric effect ,Monolayer ,lcsh:TA401-492 ,Figure of merit ,lcsh:Materials of engineering and construction. Mechanics of materials ,010306 general physics ,0210 nano-technology ,Order of magnitude - Abstract
The potential application of monolayer MS2 (M = Mo, W) as thermoelectric material has been widely studied since the first report of successful fabrication. However, their performances are hindered by the considerable band gap and the large lattice thermal conductivity in the pristine 2H phase. Recent discoveries of polymorphism in MS2s provide new opportunities for materials engineering. In this work, phonon and electron transport properties of both 2H and 1T′ phases were investigated by first-principle calculations. It is found that upon the phase transition from 2H to 1T′ in MS2, the electron transport is greatly enhanced, while the lattice thermal conductivity is reduced by several times. These features lead to a significant enhancement of power factor by one order of magnitude in MoS2 and by three times in WS2. Meanwhile, the figure of merit can reach up to 0.33 for 1T′MoS2 and 0.68 for 1T′WS2 at low temperature. These findings indicate that monolayer MS2 in the 1T′ phase can be promising materials for thermoelectric devices application. Meanwhile, this work demonstrates that phase engineering techniques can bring in one important control parameter in materials design. Keywords: Phase engineering, Thermoelectric, Transition metal dichalcogenides
- Published
- 2018
44. Low-cost and environmentally benign selenides as promising thermoelectric materials
- Author
-
Jing-Feng Li, Chao-Feng Wu, Tian-Ran Wei, and Fu Li
- Subjects
Thermoelectric efficiency ,Materials science ,Metals and Alloys ,Nanotechnology ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Thermoelectric materials ,01 natural sciences ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,chemistry.chemical_compound ,chemistry ,Selenide ,Thermoelectric effect ,lcsh:TA401-492 ,Electrical performance ,lcsh:Materials of engineering and construction. Mechanics of materials ,0210 nano-technology - Abstract
Developing high-efficiency materials with earth-abundant and low-toxicity elements has become a popular trend in the field of thermoelectrics. Among these compounds, oxides and sulfides, the lighter, cheaper and green analogies of tellurides, have been extensively investigated and summarized as well defined classes. Nonetheless, the vast family of selenides with better electrical performance, lower thermal conductivity and higher thermoelectric efficiency have not been specially discussed. Here in this review, we present recent advances in binary and multinary selenide thermoelectric materials, covering traditional PbSe, liquid-like Cu2Se, layered SnSe, diamond-like and disordered multinary compounds. The features of selenides are discussed based on both environmental concerns and from the perspective of chemical bonding, transport properties and performance. Emphasis is put on the “composition-structure-processing-performance” relationship, and some interesting issues are addressed. Finally, challenges for thermoelectric selenides are discussed, and possible optimization strategies are also suggested. Keywords: Thermoelectric materials, Selenides, Transport properties
- Published
- 2018
45. Plastic/Ductile Bulk 2D van der Waals Single‐Crystalline SnSe2 for Flexible Thermoelectrics.
- Author
-
Deng, Tingting, Gao, Zhiqiang, Qiu, Pengfei, Wei, Tian‐Ran, Xiao, Jie, Wang, Genshui, Chen, Lidong, and Shi, Xun
- Subjects
PLASTICS ,HALOGENS ,POWER density ,THERMOELECTRIC materials ,SEMICONDUCTORS - Abstract
The recently discovered ductile/plastic inorganic semiconductors pave a new avenue toward flexible thermoelectrics. However, the power factors of current ductile/plastic inorganic semiconductors are usually low (below 5 µW cm−1 K−2) as compared with classic brittle inorganic thermoelectric materials, which greatly limit the electrical output power for flexible thermoelectrics. Here, large plasticity and high power factor in bulk two‐dimensional van der Waals (2D vdW) single‐crystalline SnSe2 are reported. SnSe2 crystals exhibit large plastic strains at room temperature and they can be morphed into various shapes without cracking, which is well captured by the inherent large deformability factor. As a semiconductor, the electrical transport properties of SnSe2 can be readily tuned in a wide range by doping a tiny amount of halogen elements. A high power factor of 10.8 µW cm−1 K−2 at 375 K along the in‐plane direction is achieved in plastic single‐crystalline Br‐doped SnSe2, which is the highest value among the reported flexible inorganic and organic thermoelectric materials. Combining the good plasticity, excellent power factors, as well as low‐cost and nontoxic elements, bulk 2D vdW single‐crystalline SnSe2 shows great promise to achieve high power density for flexible thermoelectrics. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
46. Vacancy-induced heterogeneity for regulating thermoelectrics in n-type PbTe.
- Author
-
Zhong, Yan, Zhao, Xuanwei, Deng, Qian, An, Xiang, Yuan, Wei, Lv, Fangling, Gan, Lin, and Ang, Ran
- Subjects
ELECTRON transport ,THERMOELECTRIC materials ,SEEBECK coefficient ,N-type semiconductors ,PHASE separation ,CONDUCTION bands - Abstract
The fact that the thermoelectric performance is far inferior to that of p-type PbTe has inspired many strategies to develop n-type PbTe thermoelectrics. Alloying PbS in n-type PbTe effectively changes the shape of a valley to trigger a heavier conduction band for improving the Seebeck coefficient, while the resulting small orbital overlap inevitably leads to phase separation hindering electron transport. The effect of vacancies on the solubility of sulfur in n-type PbTe is ambiguous; especially, the heterostructure due to phase separation in high-content PbS-alloyed PbTe also requires sufficient modification to optimize the electroacoustic transport. This motivates the current work on the introduction of vacancies by charge-balancing doping via Sb
2 Te3 and discovers striking new insight that the introduced vacancies can induce a new heterostructure of Pb2 Sb2 S5 and suppress the aggregation of Sb and PbS in high-solubility n-type PbTe–PbS. The modification of the band structure and optimization of the electron transport give rise to a prominent enhancement in electronic performance. Furthermore, the Debye–Callaway model validates the dramatic contribution of vacancy aggregation and heterostructures to lattice thermal conductivity. As a result, the synergistic modulation of electroacoustic characteristics achieves a significant improvement in both the maximum zT and the near-room-temperature zT. Understanding such unique findings is critical for applicability to other thermoelectric materials. [ABSTRACT FROM AUTHOR]- Published
- 2022
- Full Text
- View/download PDF
47. High-Performance n-Type Ge-Free Silicon Thermoelectric Material from Silicon Waste
- Author
-
Heiko Reith, Christian G. F. Blum, Qihao Zhang, Zhenhui Liu, Christian Reimann, Jochen Friedrich, Ran He, Ulrike Wolff, Amin Bahrami, Kornelius Nielsch, Maximilian Beier-Ardizzon, Gabi Schierning, and Publica
- Subjects
Materials science ,Phonon scattering ,Silicon ,business.industry ,chemistry.chemical_element ,Thermoelectric materials ,Engineering physics ,Environmentally friendly ,Thermal conductivity ,Semiconductor ,chemistry ,Impurity ,Thermoelectric effect ,General Materials Science ,business - Abstract
Silicon waste (SW), a byproduct from the photovoltaic industry, can be a prospective and environmentally friendly source for silicon in the field of thermoelectric (TE) materials. While thermoelectricity is not as sensitive toward impurities as other semiconductor applications, the impurities within the SW still impede the enhancement of the thermoelectric figure of merit, zT. Besides, the high thermal conductivity of silicon limits its applications as a TE material. In this work, we employ traditionally metallurgical methods in industry reducing the impurities in SW to an extremely low level in an environmentally friendly and economical way, and then the thermal conductivity of purified silicon is greatly reduced due to the implementation of multiscale phonon scattering without degrading the power factor seriously. Benefiting from these strategies, from 323 to 1123 K, for the sample made from purified silicon waste, the average zT, relevant for engineering application, is increased to 0.32, higher than that of the state-of-the-art n-type Ge-free bulk silicon materials made from commercially available silicon, but the total cost of our samples is negligible.
- Published
- 2021
48. Entropy engineering induced exceptional thermoelectric and mechanical performances in Cu2-Ag Te1-2S Se
- Author
-
Pengfei Qiu, Qingyong Ren, Zixun Zhang, Lidong Chen, Tian-Ran Wei, Xun Shi, Kunpeng Zhao, Zhongmou Yue, and Heyang Chen
- Subjects
Materials science ,Polymers and Plastics ,Condensed matter physics ,Phonon scattering ,Energy conversion efficiency ,Metals and Alloys ,Thermoelectric materials ,Electronic, Optical and Magnetic Materials ,Amorphous solid ,Entropy (classical thermodynamics) ,Thermal conductivity ,Seebeck coefficient ,Thermoelectric effect ,Ceramics and Composites - Abstract
Thermoelectric materials require not only high performance to maximize the energy conversion efficiency but also good mechanical properties to guarantee machinability and reliable operation. It is usually hard to embrace both at once. Herein, we demonstrated the entropy engineering as a promising avenue to realize both exceptional thermoelectric performance and robust mechanical properties in multicomponent alloys Cu2-yAgyTe1-2xSxSex. Entropy engineering by mixing multiple elements stabilizes the high-symmetry hexagonal structure, extends the solubility limit of Ag, and concurrently lessens the phase transition numbers. Furthermore, with co-alloying of S/Se and Ag in Cu2Te, the carrier concentration is largely reduced while the effective mass is enhanced, yielding higher Seebeck coefficient and power factor. Owing to the strong phonon scattering by lattice disorder, the thermal conductivity is decreased by one order of magnitude, reaching 0.29 W m−1 K−1 at room temperature, which is even lower than the amorphous limit. A state-of-the-art peak zT of 1.4 and average zT of 0.74 are achieved in Cu1.9Ag0.1Te0.6S0.2Se0.2. Moreover, the mechanical properties are significantly improved in virtue of the entropy engineering strengthening effect, making it more promising for thermoelectric applications.
- Published
- 2022
49. Effects of Bond Strength on the Electronic Structure and Thermoelectric Properties of β‐VA Monolayers (Sb, As, and P).
- Author
-
Zhang, Shi Yang, Huang, Yong Liang, Wu, Chang Yi, Han, Jin Chen, Sun, Lei, and Gong, Hao Ran
- Subjects
THERMOELECTRIC materials ,PHONON scattering ,BOND strengths ,ELECTRONIC structure ,TRANSPORT theory ,MONOMOLECULAR films - Abstract
First‐principles calculation and Boltzmann transport theory have been combined to comparatively investigate the integration of Crystal Orbital Hamilton Populations (−ICOHP), band structures, phonon spectrums, lattice thermal conductivities, electronic transport properties, Seebeck coefficients, and thermoelectric figure of merits of β‐VA monolayers (Sb, As, and P). Calculations reveal that the thermoelectric properties increase with the decrease of the bond strength, which should be mainly due to the lower lattice thermal conductivity, suitable band gap, and weakened coupling of electrons and phonons. It is also found that the ZT value of the β‐Sb monolayer for the electronic along the x direction is the best among the β‐VA monolayers. Furthermore, the origin of the lowest lattice thermal conductivity of the β‐Sb monolayer in the β‐VA monolayers (Sb, As, and P) may be attributed to the more phonon scattering channels (P3) and the lower phonon velocity (v).The derived results are in good agreement with other theoretical results in the literature, and could provide a deep understanding of thermoelectric properties of the β‐VA monolayer materials. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
50. Optimized Strategies for Advancing n-Type PbTe Thermoelectrics: A Review
- Author
-
Yan Zhong, Ding Ren, Jing Tang, Ran Ang, Bo Liu, Liwei Lin, Zhiwei Chen, and Hangtian Liu
- Subjects
Materials science ,Semiconductor materials ,Doping ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Thermoelectric materials ,01 natural sciences ,Engineering physics ,0104 chemical sciences ,Lattice thermal conductivity ,Effective mass (solid-state physics) ,Seebeck coefficient ,Thermoelectric effect ,General Materials Science ,0210 nano-technology - Abstract
p-Type and n-type thermoelectric semiconductor materials with compatible performance are key components for thermoelectric devices. Great improvement in thermoelectric performance has been achieved in p-type PbTe, whereas the n-type counterpart still shows much inferior thermoelectric performance compared to that of the p-type PbTe. This inspires many strategies focused on advancing n-type PbTe thermoelectrics. Herein, not only effective mass engineering, resonance states, point defects, and nanostructures but also newly developed concepts including dynamic doping for stabilizing the optimal carrier concentration and introducing dislocations for reducing lattice thermal conductivity are summarized. In addition, the synergistic effects for further enhancing the thermoelectric performance are outlined, together with a discussion and outlook for boosting the advancement in n-type PbTe thermoelectric materials. Strategies discussed here are expected to be applicable to other thermoelectric materials.
- Published
- 2020
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