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nanostructured thermoelectric material

Giselle A Elbaz, Wee-Liat Ong, Evan Ambrose 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 thermal conductivities of single crystal lead halide perovskites range from 0...
August 14, 2017: Nano Letters
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
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
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
Ki Sung Kim, Young-Min Kim, Hyeona Mun, Jisoo Kim, Jucheol Park, Albina Y Borisevich, Kyu Hyoung Lee, Sung Wng Kim
Structural defects often dominate the electronic- and thermal-transport properties of thermoelectric (TE) materials and are thus a central ingredient for improving their performance. However, understanding the relationship between TE performance and the disordered atomic defects that are generally inherent in nanostructured alloys remains a challenge. Herein, the use of scanning transmission electron microscopy to visualize atomic defects directly is described and disordered atomic-scale defects are demonstrated to be responsible for the enhancement of TE performance in nanostructured Ti1-x Hfx NiSn1-y Sby half-Heusler alloys...
July 24, 2017: Advanced Materials
Kaleem Ahmad, Chunlei Wan
The advancement in nanostructured powder processing has attracted recently great interest as a cost effective and scalable strategy for high performance thermoelectric bulks. However, the level of technical breakthrough as realized in quantum dot supperlattice/wire has not yet demonstrated in these materials. Here, we report first ever study on the uniform dispersion of single wall carbon nanotubes (SWCNTs) in nanostructured Bi2Te3 bulk and their effect on thermoelectric parameters above room temperature. The Bi<sub>2</sub>Te<sub>3</sub> based SWCNTs composites were prepared through controlled powder processing and their thermoelectric properties were finely tuned at nanoscale by regulating various (0...
July 20, 2017: Nanotechnology
Biplab Paul, Jun Lu, Per Eklund
Because of their inherent rigidity and brittleness, inorganic materials have seen limited use in flexible thermoelectric applications. On the other hand, for high output power density and stability, the use of inorganic materials is required. Here, we demonstrate a concept of fully inorganic flexible thermoelectric thin films with Ca3Co4O9-on-mica. Ca3Co4O9 is promising not only because of its high Seebeck coefficient and good electrical conductivity but also because of the abundance, low cost, and nontoxicity of its constituent raw materials...
August 2, 2017: ACS Applied Materials & Interfaces
Yanguang Zhou, Xiaojing Gong, Ben Xu, Ming Hu
Thermoelectric (TE) materials manifest themselves to enable direct conversion of temperature differences to electric power and vice versa. Though remarkable advances have been achieved in the past decades for various TE systems, the energy conversion efficiency of TE devices, which is characterized by a dimensionless figure-of-merit (ZT = S(2)σT/(κel + κph)), generally remains a poor factor that severely limits TE devices' competitiveness and range of employment. The bottleneck for substantially boosting the ZT coefficient lies in the strong interdependence of the physical parameters involved in electronic (S and σ, and κel) and phononic (κph) transport...
July 20, 2017: Nanoscale
Pavlo Zolotavin, Charlotte I Evans, Douglas Natelson
Nanoscale structuring holds promise to improve the thermoelectric properties of materials for energy conversion and photodetection. We report a study of the spatial distribution of the photothermoelectric voltage in thin-film nanowire devices fabricated from a single metal. A focused laser beam is used to locally heat the metal nanostructure via a combination of direct absorption and excitation of a plasmon resonance in Au devices. As seen previously, in nanowires shorter than the spot size of the laser, we observe a thermoelectric voltage distribution that is consistent with the local Seebeck coefficient being spatially dependent on the width of the nanostructure...
July 6, 2017: Nanoscale
Hamid Emadi, Masoud Salavati-Niasari, Azam Sobhani
The design of nanostructures with favored shape, particle size and structure is one of the most important fields of nanoscience. To reach this target hydrothermal method is one of the most applicable methods which allow us to obtain favored structures by changing some parameters. This review focuses on synthesis of some transition metal sulfides by hydrothermal method because of technological importance of this group of material. The common sulfides of Mn, Co, Ni, Cu, Zn, Ag and Cd are introduced and a mechanism proposed for their synthesis...
June 16, 2017: Advances in Colloid and Interface Science
Azhar Ali, Yixi Chen, Venkata Vasiraju, Sreeram Vaddiraju
Research on thermoelectrics has seen a huge resurgence since the early 1990s. The ability of tuning a material's electrical and thermal transport behavior upon nanostructuring has led to this revival. Nevertheless, thermoelectric performances of nanowires and related materials lag far behind those achieved with thin-film superlattices and quantum dot-based materials. This is despite the fact that nanowires offer many distinct advantages in enhancing the thermoelectric performances of materials. The simplicity of the strategy is the first and foremost advantage...
June 19, 2017: Nanotechnology
Manisha Samanta, Kanishka Biswas
GeTe and its derivatives constituting Pb-free elements have been well known as potential thermoelectric materials for the last five decades, which offer paramount technological importance. The main constraint in the way of optimizing thermoelectric performance of GeTe is the high lattice thermal conductivity (κlat). Herein, we demonstrate low κlat (∼0.7 W/m·K) and a significantly high thermoelectric figure of merit (ZT = 2.1 at 630 K) in the Sb-doped pseudoternary (GeTe)1-2x(GeSe)x(GeS)x system by two-step strategies...
June 28, 2017: Journal of the American Chemical Society
Yoon-Jun Kim, Li-Dong Zhao, Mercouri G Kanatzidis, David N Seidman
The dimensionless figure of merit, ZT, of bulk thermoelectric materials depends mainly on the transport properties of charge carriers and heat-carrying phonons. PbTe-4 mol % SrTe doped with 2 mol % Na (Pb0.94Na0.02Sr0.04Te) is a nanostructured material system that exhibits a ZT higher than 2. The precipitate size distribution of SrTe precipitates is believed to play a key role. This raises the question of whether its performance is limited by precipitate coarsening (Ostwald ripening) at elevated temperatures...
June 22, 2017: ACS Applied Materials & Interfaces
Kelly W Mauser, Seyoon Kim, Slobodan Mitrovic, Dagny Fleischman, Ragip Pala, K C Schwab, Harry A Atwater
Photodetectors are typically based either on photocurrent generation from electron-hole pairs in semiconductor structures or on bolometry for wavelengths that are below bandgap absorption. In both cases, resonant plasmonic and nanophotonic structures have been successfully used to enhance performance. Here, we show subwavelength thermoelectric nanostructures designed for resonant spectrally selective absorption, which creates large localized temperature gradients even with unfocused, spatially uniform illumination to generate a thermoelectric voltage...
August 2017: Nature Nanotechnology
Da Hwi Gu, Seungki Jo, Hyewon Jeong, Hyeong Woo Ban, Sung Hoon Park, Seung Hwae Heo, Fredrick Kim, Jeong In Jang, Ji Eun Lee, Jae Sung Son
Electronically doped nanoparticles formed by incorporation of impurities have been of great interest because of their controllable electrical properties. However, the development of a strategy for n-type or p-type doping on sub-10 nm-sized nanoparticles under the quantum confinement regime is very challenging using conventional processes, owing to the difficulty in synthesis. Herein, we report the colloidal chemical synthesis of sub-10 nm-sized tellurium (Te)-doped Bismuth (Bi) nanoparticles with precisely controlled Te content from 0 to 5% and systematically investigate their low-temperature charge transport and thermoelectric properties...
June 7, 2017: ACS Applied Materials & Interfaces
Silvia Ortega, Maria Ibáñez, Yu Liu, Yu Zhang, Maksym V Kovalenko, Doris Cadavid, Andreu Cabot
The conversion of thermal energy to electricity and vice versa by means of solid state thermoelectric devices is extremely appealing. However, its cost-effectiveness is seriously hampered by the relatively high production cost and low efficiency of current thermoelectric materials and devices. To overcome present challenges and enable a successful deployment of thermoelectric systems in their wide application range, materials with significantly improved performance need to be developed. Nanostructuration can help in several ways to reach the very particular group of properties required to achieve high thermoelectric performances...
May 4, 2017: Chemical Society Reviews
Ali Kandemir, Ayberk Ozden, Tahir Cagin, Cem Sevik
Various theoretical and experimental methods are utilized to investigate the thermal conductivity of nanostructured materials; this is a critical parameter to increase performance of thermoelectric devices. Among these methods, equilibrium molecular dynamics (EMD) is an accurate technique to predict lattice thermal conductivity. In this study, by means of systematic EMD simulations, thermal conductivity of bulk Si-Ge structures (pristine, alloy and superlattice) and their nanostructured one dimensional forms with square and circular cross-section geometries (asymmetric and symmetric) are calculated for different crystallographic directions...
2017: Science and Technology of Advanced Materials
Manisha Samanta, Subhajit Roychowdhury, Jay Ghatak, Suresh Perumal, Kanishka Biswas
Waste heat sources are generally diffused and provide a range of temperatures rather than a particular temperature. Thus, thermoelectric waste heat to electricity conversion requires a high average thermoelectric figure of merit (ZTavg ) of materials over the entire working temperature along with a high peak thermoelectric figure of merit (ZTmax ). Herein an ultrahigh ZTavg of 1.4 for (GeTe)80 (AgSbSe2 )20 [TAGSSe-80, T=tellurium, A=antimony, G=germanium, S=silver, Se=selenium] is reported in the temperature range of 300-700 K, which is one of the highest values measured amongst the state-of-the-art Pb-free polycrystalline thermoelectric materials...
April 24, 2017: Chemistry: a European Journal
Yan Jin, Yingling Tan, Xiaozhen Hu, Bin Zhu, Qinghui Zheng, Zijiao Zhang, Guoying Zhu, Qian Yu, Zhong Jin, Jia Zhu
Alloy anodes possessed of high theoretical capacity show great potential for next-generation advanced lithium-ion battery. Even though huge volume change during lithium insertion and extraction leads to severe problems, such as pulverization and an unstable solid-electrolyte interphase (SEI), various nanostructures including nanoparticles, nanowires, and porous networks can address related challenges to improve electrochemical performance. However, the complex and expensive fabrication process hinders the widespread application of nanostructured alloy anodes, which generate an urgent demand of low-cost and scalable processes to fabricate building blocks with fine controls of size, morphology, and porosity...
April 25, 2017: ACS Applied Materials & Interfaces
Zhiwei Chen, Zhengzhong Jian, Wen Li, Yunjie Chang, Binghui Ge, Riley Hanus, Jiong Yang, Yue Chen, Mingxin Huang, Gerald Jeffrey Snyder, Yanzhong Pei
Phonon scattering by nanostructures and point defects has become the primary strategy for minimizing the lattice thermal conductivity (κL ) in thermoelectric materials. However, these scatterers are only effective at the extremes of the phonon spectrum. Recently, it has been demonstrated that dislocations are effective at scattering the remaining mid-frequency phonons as well. In this work, by varying the concentration of Na in Pb0.97 Eu0.03 Te, it has been determined that the dominant microstructural features are point defects, lattice dislocations, and nanostructure interfaces...
April 11, 2017: Advanced Materials
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