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nanostructured thermoelectric material

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https://www.readbyqxmd.com/read/27878169/in-situ-characterisation-of-nanostructured-multiphase-thermoelectric-materials-at-elevated-temperatures
#1
S Aminorroaya Yamini, D R G Mitchell, M Avdeev
Multiphase thermoelectric materials have recently attracted considerable attention due to the high thermoelectric efficiencies which can be achieved in these compounds compared to their single-phase counterparts. However, there is very little known on the structural evolution of these phases as a function of temperature. In this work we performed an in situ high temperature structural characterisation of recently reported high efficiency p-type multiphase (PbTe)0.65(PbS)0.25(PbSe)0.1 compounds by hot stage transmission electron microscopy and high-resolution neutron powder diffraction...
November 23, 2016: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/27874117/quantitative-analyses-of-enhanced-thermoelectric-properties-of-modulation-doped-pedot-pss-undoped-si-001-nanoscale-heterostructures
#2
Dongwook Lee, Sayed Youssef Sayed, Sangyeop Lee, Chris Adam Kuryak, Jiawei Zhou, Gang Chen, Yang Shao-Horn
Poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) has high electrical conductivity (∼10(3) S cm(-1)) but it exhibits a low Seebeck coefficient (<15 μV K(-1)), resulting in a low power factor. Mixing PEDOT:PSS with nanostructured semiconductors can enhance the Seebeck coefficient and achieve an improved thermoelectric power factor. However, underlying mechanisms for those composite thermoelectric systems are scarcely understood so far. In this study, quantitative analyses on the electrical conductivity and Seebeck coefficient for the heterostructures of nanometer-thick PEDOT:PSS on single-crystal Si (001) on sapphire (SOS) are reported...
December 1, 2016: Nanoscale
https://www.readbyqxmd.com/read/27830698/direct-observation-of-confined-acoustic-phonon-polarization-branches-in-free-standing-semiconductor-nanowires
#3
Fariborz Kargar, Bishwajit Debnath, Joona-Pekko Kakko, Antti Säynätjoki, Harri Lipsanen, Denis L Nika, Roger K Lake, Alexander A Balandin
Similar to electron waves, the phonon states in semiconductors can undergo changes induced by external boundaries. However, despite strong scientific and practical importance, conclusive experimental evidence of confined acoustic phonon polarization branches in individual free-standing nanostructures is lacking. Here we report results of Brillouin-Mandelstam light scattering spectroscopy, which reveal multiple (up to ten) confined acoustic phonon polarization branches in GaAs nanowires with a diameter as large as 128 nm, at a length scale that exceeds the grey phonon mean-free path in this material by almost an order-of-magnitude...
November 10, 2016: Nature Communications
https://www.readbyqxmd.com/read/27763764/extraordinary-off-stoichiometric-bismuth-telluride-for-enhanced-n-type-thermoelectric-power-factor
#4
Kunsu Park, Kyunghan Ahn, Joonil Cha, Sanghwa Lee, Sue In Chae, Sung-Pyo Cho, Siheon Ryee, Jino Im, Jaeki Lee, Su-Dong Park, Myung Joon Han, In Chung, Taeghwan Hyeon
Thermoelectrics directly converts waste heat into electricity and is considered a promising means of sustainable energy generation. While most of the recent advances in the enhancement of the thermoelectric figure of merit (ZT) resulted from a decrease in lattice thermal conductivity by nanostructuring, there have been very few attempts to enhance electrical transport properties, i.e., the power factor. Here we use nanochemistry to stabilize bulk bismuth telluride (Bi2Te3) that violates phase equilibrium, namely, phase-pure n-type K0...
October 20, 2016: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/27704857/precise-perforation-and-scalable-production-of-si-particles-from-low-grade-sources-for-high-performance-lithium-ion-battery-anodes
#5
Linqi Zong, Yan Jin, Chang Liu, Bin Zhu, Xiaozhen Hu, Zhenda Lu, Jia Zhu
Alloy anodes, particularly silicon has been intensively pursued as one of the most promising anode materials for next generation lithium-ion battery primarily because of high specific capacity (>4000 mAh/g) and elemental abundance. In the past decade, various nanostructures with porosity or void space designs have been demonstrated to be effective to accommodate large volume expansion (~300%) and to provide stable solid electrolyte interphase (SEI) during electrochemical cycling. However, how to produce these building blocks with precise morphology control at large scale and low cost remains a challenge...
October 5, 2016: Nano Letters
https://www.readbyqxmd.com/read/27696882/hot-carrier-extraction-from-multilayer-graphene
#6
Roberto Urcuyo, Dinh Loc Duong, Patrick Sailer, Marko Burghard, Klaus Kern
Hot carriers in semiconductor or metal nanostructures are relevant, for instance, to enhance the activity of oxide-supported metal catalysts, or to achieve efficient photo-detection using ultrathin semiconductor layers. Moreover, rapid collection of photo-excited hot carriers can improve the efficiency of solar cells, with a theoretical maximum of 85%. Owing to its strong electron-electron interactions, graphene is an especially promising two-dimensional material to harness hot carriers for solar-to-electricity conversion...
October 3, 2016: Nano Letters
https://www.readbyqxmd.com/read/27669055/phonon-transport-in-single-layer-boron-nanoribbons
#7
Zhongwei Zhang, Yuee Xie, Qing Peng, Yuanping Chen
Inspired by the successful synthesis of three two-dimensional (2D) allotropes, the boron sheet has recently been one of the hottest 2D materials around. However, to date, phonon transport properties of these new materials are still unknown. By using the non-equilibrium Green's function (NEGF) combined with the first principles method, we study ballistic phonon transport in three types of boron sheets; two of them correspond to the structures reported in the experiments, while the third one is a stable structure that has not been synthesized yet...
November 4, 2016: Nanotechnology
https://www.readbyqxmd.com/read/27603153/record-low-thermal-conductivity-of-polycrystalline-si-nanowire-breaking-the-casimir-limit-by-severe-suppression-of-propagons
#8
Yanguang Zhou, Ming Hu
Thermoelectrics offer an attractive pathway for addressing an important niche in the globally growing landscape of energy demand. Nanoengineering existing low-dimensional thermoelectric materials pertaining to realizing fundamentally low thermal conductivity has emerged as an efficient route to achieve high energy conversion performance for advanced thermoelectrics. In this paper, by performing nonequilibrium and Green-Kubo equilibrium molecular dynamics simulations we report that the thermal conductivity of Si nanowires (NWs) in polycrystalline form can reach a record low value substantially below the Casimir limit, a theory of diffusive boundary limit that regards the direction-averaged mean free path is limited by the characteristic size of the nanostructures...
October 12, 2016: Nano Letters
https://www.readbyqxmd.com/read/27580481/rationally-designing-high-performance-bulk-thermoelectric-materials
#9
Gangjian Tan, Li-Dong Zhao, Mercouri G Kanatzidis
There has been a renaissance of interest in exploring highly efficient thermoelectric materials as a possible route to address the worldwide energy generation, utilization, and management. This review describes the recent advances in designing high-performance bulk thermoelectric materials. We begin with the fundamental stratagem of achieving the greatest thermoelectric figure of merit ZT of a given material by carrier concentration engineering, including Fermi level regulation and optimum carrier density stabilization...
October 12, 2016: Chemical Reviews
https://www.readbyqxmd.com/read/27569053/ab-initio-based-bond-order-potential-to-investigate-low-thermal-conductivity-of-stanene-nanostructures
#10
Mathew J Cherukara, Badri Narayanan, Alper Kinaci, Kiran Sasikumar, Stephen K Gray, Maria K Y Chan, Subramanian K R S Sankaranarayanan
We introduce a bond order potential (BOP) for stanene based on an ab initio derived training data set. The potential is optimized to accurately describe the energetics, as well as thermal and mechanical properties of a free-standing sheet, and used to study diverse nanostructures of stanene, including tubes and ribbons. As a representative case study, using the potential, we perform molecular dynamics simulations to study stanene's structure and temperature-dependent thermal conductivity. We find that the structure of stanene is highly rippled, far in excess of other 2-D materials (e...
October 6, 2016: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/27519021/nanoscale-solid-state-cooling-a-review
#11
Amirkoushyar Ziabari, Mona Zebarjadi, Daryoosh Vashaee, Ali Shakouri
The recent developments in nanoscale solid-state cooling are reviewed. This includes both theoretical and experimental studies of different physical concepts, as well as nanostructured material design and device configurations. We primarily focus on thermoelectric, thermionic and thermo-magnetic coolers. Particular emphasis is given to the concepts based on metal-semiconductor superlattices, graded materials, non-equilibrium thermoelectric devices, Thomson coolers, and photon assisted Peltier coolers as promising methods for efficient solid-state cooling...
September 2016: Reports on Progress in Physics
https://www.readbyqxmd.com/read/27502192/solvothermal-synthesis-structure-and-optical-property-of-nanosized-cosb3-skutterudite
#12
Latha Kumari, Wenzhi Li, JianYu Huang, Paula P Provencio
Binary skutterudite CoSb3 nanoparticles were synthesized by solvothermal method. The nanostructuring of CoSb3 material was achieved by the inclusion of various kinds of additives. X-ray diffraction examination indicated the formation of the cubic phase of CoSb3. Structural analysis by transmission electron microscopy analysis further confirmed the formation of crystalline CoSb3 nanoparticles with high purity. With the assistance of additives, CoSb3 nanoparticles with size as small as 10 nm were obtained. The effect of the nanostructure of CoSb3 on the UV-visible absorption and luminescence was studied...
October 2010: Nanoscale Research Letters
https://www.readbyqxmd.com/read/27456303/non-equilibrium-processing-leads-to-record-high-thermoelectric-figure-of-merit-in-pbte-srte
#13
Gangjian Tan, Fengyuan Shi, Shiqiang Hao, Li-Dong Zhao, Hang Chi, Xiaomi Zhang, Ctirad Uher, Chris Wolverton, Vinayak P Dravid, Mercouri G Kanatzidis
The broad-based implementation of thermoelectric materials in converting heat to electricity hinges on the achievement of high conversion efficiency. Here we demonstrate a thermoelectric figure of merit ZT of 2.5 at 923 K by the cumulative integration of several performance-enhancing concepts in a single material system. Using non-equilibrium processing we show that hole-doped samples of PbTe can be heavily alloyed with SrTe well beyond its thermodynamic solubility limit of <1 mol%. The much higher levels of Sr alloyed into the PbTe matrix widen the bandgap and create convergence of the two valence bands of PbTe, greatly boosting the power factors with maximal values over 30 μW cm(-1) K(-2)...
2016: Nature Communications
https://www.readbyqxmd.com/read/27454037/large-area-thermoelectric-high-aspect-ratio-nanostructures-by-atomic-layer-deposition
#14
Mikko Ruoho, Taneli Juntunen, Ilkka Tittonen
We report on the thermoelectric properties of large-area high-aspect-ratio nanostructures. We fabricate the structures by atomic layer deposition of conformal ZnO thin films on track-etched polycarbonate substrate. The resulting structure consists of ZnO tubules which continue through the full thickness of the substrate. The electrical and thermal properties of the structures are studied both in-plane and out-of-plane. They exhibit very low out-of-plane thermal conductivity down to 0.15 W m(-1) K(-1) while the in-plane sheet resistance of the films was found to be half that of the same film on glass substrate, allowing material-independent doubling of output power of any planar thin-film thermoelectric generator...
September 2, 2016: Nanotechnology
https://www.readbyqxmd.com/read/27397515/spinodally-decomposed-pbse-pbte-nanoparticles-for-high-performance-thermoelectrics-enhanced-phonon-scattering-and-unusual-transport-behavior
#15
Min-Seok Kim, Woo-Jin Lee, Ki-Hyun Cho, Jae-Pyoung Ahn, Yun-Mo Sung
Dramatic enhancements in the figure of merit have been obtained in bulk thermoelectric materials by doping, band engineering, and nanostructuring. Especially, in p-type thermoelectrics, high figure of merits near 2.0 have been reported in a few papers through the reduction in lattice thermal conductivity and the advancement in power factors. However, there exists no report on the n-type systems showing high figure of merits because of their intrinsically low Seebeck coefficients. Here, we demonstrate that a nanostructured bulk n-type thermoelectric material that was assembled by sintering spinodally decomposed lead chalcogenide nanoparticles having a composition of PbSe0...
July 26, 2016: ACS Nano
https://www.readbyqxmd.com/read/27385824/higher-thermoelectric-performance-of-zintl-phases-eu0-5yb0-5-1-xcaxmg2bi2-by-band-engineering-and-strain-fluctuation
#16
Jing Shuai, Huiyuan Geng, Yucheng Lan, Zhuan Zhu, Chao Wang, Zihang Liu, Jiming Bao, Ching-Wu Chu, Jiehe Sui, Zhifeng Ren
Complex Zintl phases, especially antimony (Sb)-based YbZn0.4Cd1.6Sb2 with figure-of-merit (ZT) of ∼1.2 at 700 K, are good candidates as thermoelectric materials because of their intrinsic "electron-crystal, phonon-glass" nature. Here, we report the rarely studied p-type bismuth (Bi)-based Zintl phases (Ca,Yb,Eu)Mg2Bi2 with a record thermoelectric performance. Phase-pure EuMg2Bi2 is successfully prepared with suppressed bipolar effect to reach ZT ∼ 1. Further partial substitution of Eu by Ca and Yb enhanced ZT to ∼1...
July 19, 2016: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/27358737/transition-metal-nitride-based-thin-films-as-novel-energy-harvesting-materials
#17
Per Eklund, Sit Kerdsongpanya, Björn Alling
The last few years have seen a rise in the interest in early transition-metal and rare-earth nitrides, primarily based on ScN and CrN, for energy harvesting by thermoelectricity and piezoelectricity. This is because of a number of important advances, among those the discoveries of exceptionally high piezoelectric coupling coefficient in (Sc,Al)N alloys and of high thermoelectric power factors of ScN-based and CrN-based thin films. These materials also constitute well-defined model systems for investigating thermodynamics of mixing for alloying and nanostructural design for optimization of phase stability and band structure...
May 14, 2016: Journal of Materials Chemistry. C, Materials for Optical and Electronic Devices
https://www.readbyqxmd.com/read/27344991/thermal-transport-in-si-and-ge-nanostructures-in-the-confinement-regime
#18
Soonshin Kwon, Matthew C Wingert, Jianlin Zheng, Jie Xiang, Renkun Chen
Reducing semiconductor materials to sizes comparable to the characteristic lengths of phonons, such as the mean-free-path (MFP) and wavelength, has unveiled new physical phenomena and engineering capabilities for thermal energy management and conversion systems. These developments have been enabled by the increasing sophistication of chemical synthesis, microfabrication, and atomistic simulation techniques to understand the underlying mechanisms of phonon transport. Modifying thermal properties by scaling physical size is particularly effective for materials which have large phonon MFPs, such as crystalline Si and Ge...
July 21, 2016: Nanoscale
https://www.readbyqxmd.com/read/27285719/nondestructive-measurement-of-the-evolution-of-layer-specific-mechanical-properties-in-sub-10-nm-bilayer-films
#19
Kathleen M Hoogeboom-Pot, Emrah Turgut, Jorge N Hernandez-Charpak, Justin M Shaw, Henry C Kapteyn, Margaret M Murnane, Damiano Nardi
We use short wavelength extreme ultraviolet light to independently measure the mechanical properties of disparate layers within a bilayer film for the first time, with single-monolayer sensitivity. We show that in Ni/Ta nanostructured systems, while their density ratio is not meaningfully changed from that expected in bulk, their elastic properties are significantly modified, where nickel softens while tantalum stiffens, relative to their bulk counterparts. In particular, the presence or absence of the Ta capping layer influences the mechanical properties of the Ni film...
August 10, 2016: Nano Letters
https://www.readbyqxmd.com/read/27251233/giant-seebeck-effect-in-ge-doped-snse
#20
M Gharsallah, F Serrano-Sánchez, N M Nemes, F J Mompeán, J L Martínez, M T Fernández-Díaz, F Elhalouani, J A Alonso
Thermoelectric materials may contribute in the near future as new alternative sources of sustainable energy. Unprecedented thermoelectric properties in p-type SnSe single crystals have been recently reported, accompanied by extremely low thermal conductivity in polycrystalline samples. In order to enhance thermoelectric efficiency through proper tuning of this material we report a full structural characterization and evaluation of the thermoelectric properties of novel Ge-doped SnSe prepared by a straightforward arc-melting method, which yields nanostructured polycrystalline samples...
2016: Scientific Reports
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