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nanostructured thermoelectric material

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https://www.readbyqxmd.com/read/29339581/strain-induced-bi-thermoelectricity-in-tapered-carbon-nanotubes
#1
Laith A Algharagholy, Tom Pope, Colin J Lambert
We show that carbon-based nanostructured materials are a novel testbed for controlling thermoelectricity and have the potential to underpin the development of new cost-effective environmentally-friendly thermoelectric materials. In single-molecule junctions, it is known that transport resonances associated with the discrete molecular levels play a key role in the thermoelectric performance, but such resonances have not been exploited in carbon nanotubes (CNTs). Here we study junctions formed from tapered CNTs and demonstrate that such structures possess transport resonances near the Fermi level, whose energetic location can be varied by applying strain, resulting in an ability to tune the sign of their Seebeck coefficient...
January 17, 2018: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/29339475/electron-mean-free-path-filtering-in-dirac-material-for-improved-thermoelectric-performance
#2
Te-Huan Liu, Jiawei Zhou, Mingda Li, Zhiwei Ding, Qichen Song, Bolin Liao, Liang Fu, Gang Chen
Recent advancements in thermoelectric materials have largely benefited from various approaches, including band engineering and defect optimization, among which the nanostructuring technique presents a promising way to improve the thermoelectric figure of merit (zT) by means of reducing the characteristic length of the nanostructure, which relies on the belief that phonons' mean free paths (MFPs) are typically much longer than electrons'. Pushing the nanostructure sizes down to the length scale dictated by electron MFPs, however, has hitherto been overlooked as it inevitably sacrifices electrical conduction...
January 16, 2018: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/29323485/spark-plasma-sintering-sps-assisted-synthesis-and-thermoelectric-characterization-of-magn%C3%A3-li-phase-v6o11
#3
Markus Joos, Giacomo Cerretti, Igor Veremchuk, Patrick Hofmann, Hajo Frerichs, Dalaver H Anjum, Tobias Reich, Ingo Lieberwirth, Martin Panthöfer, Wolfgang G Zeier, Wolfgang Tremel
The Magnéli phase V6O11 was synthesized in gram amounts from a powder mixture of V6O11/V7O13 and vanadium metal, using the spark plasma sintering (SPS) technique. Its structure was determined with synchrotron X-ray powder diffraction data from a phase-pure sample synthesized by conventional solid-state synthesis. A special feature of Magnéli-type oxides is a combination of crystallographic shear and intrinsic disorder that leads to relatively low lattice thermal conductivities. SPS prepared V6O11 has a relatively low thermal conductivity of κ = 2...
January 11, 2018: Inorganic Chemistry
https://www.readbyqxmd.com/read/29319087/significant-enhancement-in-thermoelectric-performance-of-nanostructured-higher-manganese-silicides-synthesized-employing-a-melt-spinning-technique
#4
Saravanan Muthiah, R C Singh, B D Pathak, Piyush Kumar Avasthi, Rishikesh Kumar, Anil Kumar, A K Srivastava, Ajay Dhar
The limited thermoelectric performance of p-type Higher Manganese Silicides (HMS) in terms of their low figure-of-merit (ZT), which is far below unity, is the main bottle-neck for realising an efficient HMS based thermoelectric generator, which has been recognized as the most promising material for harnessing waste-heat in the mid-temperature range, owing to its thermal stability, earth-abundant and environmentally friendly nature of its constituent elements. We report a significant enhancement in the thermoelectric performance of nanostructured HMS synthesized using rapid solidification by optimizing the cooling rates during melt-spinning followed by spark plasma sintering of the resulting melt-spun ribbons...
January 10, 2018: Nanoscale
https://www.readbyqxmd.com/read/29313341/grain-by-grain-compositional-variations-and-interstitial-metals-a-new-route-towards-achieving-high-performance-in-half-heusler-thermoelectrics
#5
Sonia Agata Barczak, John Halpin, Jim Buckman, Rodolphe Decourt, Michael Pollet, Ronald I Smith, Donald Maclaren, Jan-Willem G Bos
Half-Heusler alloys based on TiNiSn are promising thermoelectric materials characterised by large power factors, good mechanical and thermal stabilities; but they are limited by large thermal conductivities. A variety of strategies have been used to disrupt their thermal transport, including alloying with heavy, generally expensive, elements and nanostructuring, enabling figures of merit, ZT ≥ 1 at elevated temperatures (>773 K). Here, we demonstrate an alternative strategy that is based around the partial segregation of excess Cu leading to grain-by-grain compositional variations, the formation of extruded Cu 'wetting' layers between grains and - most importantly - the presence of statistically distributed interstitials that reduce the thermal conductivity effectively through point-defect scattering...
January 9, 2018: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/29199973/thermal-conductivity-anisotropy-in-holey-silicon-nanostructures-and-its-impact-on-thermoelectric-cooling
#6
Zongqing Ren, Jaeho Lee
Artificial nanostructures have improved prospects of thermoelectric systems by enabling selective scattering of phonons and demonstrating significant thermal conductivity reductions. While the low thermal conductivity provides necessary temperature gradients for thermoelectric conversion, the heat generation is detrimental to electronic systems where high thermal conductivity are preferred. The contrasting needs of thermal conductivity are evident in thermoelectric cooling systems, which call for a fundamental breakthrough...
December 4, 2017: Nanotechnology
https://www.readbyqxmd.com/read/29193369/soft-chemistry-coloring-and-polytypism-of-filled-tetrahedral-semiconductors-toward-enhanced-thermoelectric-and-battery-materials
#7
Miles Arthur B White, Alan Misael Medina-Gonzalez, Javier Vela
Filled tetrahedral semiconductors are a rich family of compounds with tunable electronic structure, making them ideal for applications in thermoelectrics, photovoltaics, and battery anodes. Furthermore, these materials crystallize in a plethora of related structures that are very close in energy, giving rise to polytypism through the manipulation of synthetic parameters. This minireview highlights recent advances in the solution phase synthesis and nanostructuring of these materials. These methods enable the synthesis of metastable phases and polytypes that were previously unobtainable...
November 28, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/29158514/large-magneto-seebeck-effect-in-magnetic-tunnel-junctions-with-half-metallic-heusler-electrodes
#8
Alexander Boehnke, Ulrike Martens, Christian Sterwerf, Alessia Niesen, Torsten Huebner, Marvin von der Ehe, Markus Meinert, Timo Kuschel, Andy Thomas, Christian Heiliger, Markus Münzenberg, Günter Reiss
Spin caloritronics studies the interplay between charge-, heat- and spin-currents, which are initiated by temperature gradients in magnetic nanostructures. A plethora of new phenomena has been discovered that promises, e.g., to make wasted heat in electronic devices useable or to provide new read-out mechanisms for information. However, only few materials have been studied so far with Seebeck voltages of only some microvolt, which hampers applications. Here, we demonstrate that half-metallic Heusler compounds are hot candidates for enhancing spin-dependent thermoelectric effects...
November 20, 2017: Nature Communications
https://www.readbyqxmd.com/read/29116809/thermoelectricity-enhanced-electrocatalysis
#9
Tiva Sharifi, Xiang Zhang, Gelu Costin, Sadegh Yazdi, Cristiano F Woellner, Yang Liu, Chandra Sekhar Tiwary, Pulickel Ajayan
We show that thermoelectric materials can function as electrocatalysts and use thermoelectric voltage generated to initiate and boost electrocatalytic reactions. The electrocatalytic activity is promoted by the use of nanostructured thermoelectric materials in a hydrogen evolution reaction (HER) by the thermoelectricity generated from induced temperature gradients. This phenomenon is demonstrated using two-dimensional layered thermoelectric materials Sb2Te3 and Bi0.5Sb1.5Te3 where a current density approaching ∼50 mA/cm(2) is produced at zero potential for Bi0...
November 13, 2017: Nano Letters
https://www.readbyqxmd.com/read/29044163/materials-analysis-and-focused-ion-beam-nanofabrication-of-topological-insulator-bi2se3
#10
Sarah Friedensen, Jerome T Mlack, Marija Drndić
Focused ion beam milling allows manipulation of the shape and size of nanostructures to create geometries potentially useful for opto-electronics, thermoelectrics, and quantum computing. We focus on using the ion beam to control the thickness of Bi2Se3 and to create nanowires from larger structures. Changes in the material structure of Bi2Se3 nanomaterials that have been milled using a focused ion beam are presented. In order to characterize the effects of ion beam processing on the samples, we use a variety of techniques including analytical transmission electron microscopy and atomic force microscopy...
October 18, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28991398/in-situ-tem-studies-of-nanostructured-thermoelectric-materials-an-application-to-mg-doped-zn4sb3-alloy
#11
Duc-The Ngo, Hung Thanh Le, Nong Van Ngo
We demonstrate an advanced approach using advanced in-situ transmission electron microscopy (TEM) to understand the interplay between nanostructures and thermoelectric (TE) properties of high-performance Mg-doped Zn4Sb3 TE system. With the technique, microstructure and crystal evolutions of TE material have been dynamically captured as a function of temperature from 300 K to 573 K. On heating, we have observed clearly precipitation and growth of a Zn-rich secondary phase as nanoinclusions in the matrix of primary Zn4Sb3 phase...
October 9, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28961360/novel-principles-and-nanostructuring-methods-for-enhanced-thermoelectrics
#12
REVIEW
Takao Mori
Thermoelectrics (TE), the direct solid-state conversion of waste heat to electricity, is a promising field with potential wide-scale application for power generation. Intrinsic conflicts in the requirements for high electrical conductivity but (a) low thermal conductivity and (b) a large Seebeck coefficient have made enhancing TE performance difficult. Several recent striking advances in the field are reviewed. In regard to the former conflict, notable bottom-up nanostructuring methods for phonon-selective scattering are discovered, namely using nanosheets, dislocations, and most strikingly a process to fabricate nano-micropores leading to a 100% enhancement in the figure of merit (ZT ≈ 1...
September 29, 2017: Small
https://www.readbyqxmd.com/read/28938831/ab-initio-electronic-transport-and-thermoelectric-properties-of-solids-from-full-and-range-separated-hybrid-functionals
#13
Giuseppe Sansone, Andrea Ferretti, Lorenzo Maschio
Within the semiclassical Boltzmann transport theory in the constant relaxation-time approximation, we perform an ab initio study of the transport properties of selected systems, including crystalline solids and nanostructures. A local (Gaussian) basis set is adopted and exploited to analytically evaluate band velocities as well as to access full and range-separated hybrid functionals (such as B3LYP, PBE0, or HSE06) at a moderate computational cost. As a consequence of the analytical derivative, our approach is computationally efficient and does not suffer from problems related to band crossings...
September 21, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28905895/superparamagnetic-enhancement-of-thermoelectric-performance
#14
Wenyu Zhao, Zhiyuan Liu, Zhigang Sun, Qingjie Zhang, Ping Wei, Xin Mu, Hongyu Zhou, Cuncheng Li, Shifang Ma, Danqi He, Pengxia Ji, Wanting Zhu, Xiaolei Nie, Xianli Su, Xinfeng Tang, Baogen Shen, Xiaoli Dong, Jihui Yang, Yong Liu, Jing Shi
The ability to control chemical and physical structuring at the nanometre scale is important for developing high-performance thermoelectric materials. Progress in this area has been achieved mainly by enhancing phonon scattering and consequently decreasing the thermal conductivity of the lattice through the design of either interface structures at nanometre or mesoscopic length scales or multiscale hierarchical architectures. A nanostructuring approach that enables electron transport as well as phonon transport to be manipulated could potentially lead to further enhancements in thermoelectric performance...
September 13, 2017: Nature
https://www.readbyqxmd.com/read/28902205/electron-phonon-scattering-effect-on-the-lattice-thermal-conductivity-of-silicon-nanostructures
#15
Bo Fu, Guihua Tang, Yifei Li
Nanostructuring technology has been widely employed to reduce the thermal conductivity of thermoelectric materials because of the strong phonon-boundary scattering. Optimizing the carrier concentration can not only improve the electrical properties, but also affect the lattice thermal conductivity significantly due to the electron-phonon scattering. The lattice thermal conductivity of silicon nanostructures considering electron-phonon scattering is investigated for comparing the lattice thermal conductivity reductions resulting from nanostructuring technology and the carrier concentration optimization...
November 1, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28833788/extraordinary-thermoelectric-performance-realized-in-n-type-pbte-through-multiphase-nanostructure-engineering
#16
Jian Zhang, Di Wu, Dongsheng He, Dan Feng, Meijie Yin, Xiaoying Qin, Jiaqing He
Lead telluride has long been realized as an ideal p-type thermoelectric material at an intermediate temperature range; however, its commercial applications are largely restricted by its n-type counterpart that exhibits relatively inferior thermoelectric performance. This major limitation is largely solved here, where it is reported that a record-high ZT value of ≈1.83 can be achieved at 773 K in n-type PbTe-4%InSb composites. This significant enhancement in thermoelectric performance is attributed to the incorporation of InSb into the PbTe matrix resulting in multiphase nanostructures that can simultaneously modulate the electrical and thermal transport...
August 21, 2017: Advanced Materials
https://www.readbyqxmd.com/read/28806090/phonon-speed-not-scattering-differentiates-thermal-transport-in-lead-halide-perovskites
#17
Giselle A Elbaz, Wee-Liat Ong, Evan A Doud, Philip Kim, Daniel W Paley, Xavier Roy, Jonathan A Malen
Thermal management plays a critical role in the design of solid state materials for energy conversion. Lead halide perovskites have emerged as promising candidates for photovoltaic, thermoelectric, and optoelectronic applications, but their thermal properties are still poorly understood. Here, we report on the thermal conductivity, elastic modulus, and sound speed of a series of lead halide perovskites MAPbX3 (X = Cl, Br, I), CsPbBr3, and FAPbBr3 (MA = methylammonium, FA = formamidinium). Using frequency domain thermoreflectance, we find that the room temperature thermal conductivities of single crystal lead halide perovskites range from 0...
September 13, 2017: Nano Letters
https://www.readbyqxmd.com/read/28772777/thermoelectric-transport-in-nanocomposites
#18
REVIEW
Bin Liu, Jizhu Hu, Jun Zhou, Ronggui Yang
Thermoelectric materials which can convert energies directly between heat and electricity are used for solid state cooling and power generation. There is a big challenge to improve the efficiency of energy conversion which can be characterized by the figure of merit (ZT). In the past two decades, the introduction of nanostructures into bulk materials was believed to possibly enhance ZT. Nanocomposites is one kind of nanostructured material system which includes nanoconstituents in a matrix material or is a mixture of different nanoconstituents...
April 15, 2017: Materials
https://www.readbyqxmd.com/read/28772593/large-scale-surfactant-free-synthesis-of-p-type-snte-nanoparticles-for-thermoelectric-applications
#19
Guang Han, Ruizhi Zhang, Srinivas R Popuri, Heather F Greer, Michael J Reece, Jan-Willem G Bos, Wuzong Zhou, Andrew R Knox, Duncan H Gregory
A facile one-pot aqueous solution method has been developed for the fast and straightforward synthesis of SnTe nanoparticles in more than ten gram quantities per batch. The synthesis involves boiling an alkaline Na₂SnO₂ solution and a NaHTe solution for short time scales, in which the NaOH concentration and reaction duration play vital roles in controlling the phase purity and particle size, respectively. Spark plasma sintering of the SnTe nanoparticles produces nanostructured compacts that have a comparable thermoelectric performance to bulk counterparts synthesised by more time- and energy-intensive methods...
February 26, 2017: Materials
https://www.readbyqxmd.com/read/28740227/enhanced-figure-of-merit-in-nanostructured-bi-sb-2te3-with-optimized-composition-prepared-by-a-straightforward-arc-melting-procedure
#20
F Serrano-Sánchez, M Gharsallah, N M Nemes, N Biskup, M Varela, J L Martínez, M T Fernández-Díaz, J A Alonso
Sb-doped Bi2Te3 is known since the 1950s as the best thermoelectric material for near-room temperature operation. Improvements in material performance are expected from nanostructuring procedures. We present a straightforward and fast method to synthesize already nanostructured pellets that show an enhanced ZT due to a remarkably low thermal conductivity and unusually high Seebeck coefficient for a nominal composition optimized for arc-melting: Bi0.35Sb1.65Te3. We provide a detailed structural analysis of the Bi2-xSbxTe3 series (0 ≤ x ≤ 2) based on neutron powder diffraction as a function of composition and temperature that reveals the important role played by atomic vibrations...
July 24, 2017: Scientific Reports
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