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Alireza Faghaninia, Guodong Yu, Umut Aydemir, Max Wood, Wei Chen, Gian-Marco Rignanese, G Jeffrey Snyder, Geoffroy Hautier, Anubhav Jain
Bournonite (CuPbSbS3) is an earth-abundant mineral with potential thermoelectric applications. This material has a complex crystal structure (space group Pmn21 #31) and has previously been measured to exhibit a very low thermal conductivity (κ < 1 W m(-1) K(-1) at T ≥ 300 K). In this study, we employ high-throughput density functional theory calculations to investigate how the properties of the bournonite crystal structure change with elemental substitutions. Specifically, we compute the stability and electronic properties of 320 structures generated via substitutions {Na-K-Cu-Ag}{Si-Ge-Sn-Pb}{N-P-As-Sb-Bi}{O-S-Se-Te} in the ABCD3 formula...
February 17, 2017: Physical Chemistry Chemical Physics: PCCP
Kazuhiro Kirihara, Masakazu Mukaida, Yoshiki Shimizu
The electrical transport and thermoelectric property of boron carbide nanowires synthesized by a carbothermal method are reported. It is demonstrated that the nanowires achieve a higher Seebeck coefficient and power factor than those of the bulk samples. The conduction mechanism of the nanowires at low temperatures below 300 K is different from that of the sintered-polycrystalline and single-crystal bulk samples. In a temperature range of 200 to 450 K, there is a crossover between electrical conduction by variable-range hopping and phonon-assisted hopping...
February 16, 2017: Nanotechnology
Zhongrui Li, Zhiyong Liang
A series of flattened-nanotube reinforced thermoplastic composites are sizably fabricated as a function of buckypaper loading. The effects of the volume fraction, nanotube alignment and length on the tensile performance of the composites are factored into a general expression. The incorporation of self-reinforcing polyphenylene resin (Parmax) into a highly aligned buckypaper frame at an optimal weight ratio boosts the tensile strength and Young's modulus of the buckypaper/Parmax composite to 1145 MPa and 150 GPa, respectively, far exceeding those of Parmax and aligned buckypaper individually...
February 13, 2017: Scientific Reports
Teng Ma, Zhibo Liu, Jinxiu Wen, Yang Gao, Xibiao Ren, Huanjun Chen, Chuanhong Jin, Xiu-Liang Ma, Ningsheng Xu, Hui-Ming Cheng, Wencai Ren
Understanding the influence of grain boundaries (GBs) on the electrical and thermal transport properties of graphene films is essentially important for electronic, optoelectronic and thermoelectric applications. Here we report a segregation-adsorption chemical vapour deposition method to grow well-stitched high-quality monolayer graphene films with a tunable uniform grain size from ∼200 nm to ∼1 μm, by using a Pt substrate with medium carbon solubility, which enables the determination of the scaling laws of thermal and electrical conductivities as a function of grain size...
February 16, 2017: Nature Communications
José Eduardo Barrios-Vargas, Bohayra Mortazavi, Aron W Cummings, Rafael Martinez-Gordillo, Miguel Pruneda, Luciano Colombo, Timon Rabczuk, Stephan Roche
We present a theoretical study of electronic and thermal transport in polycrystalline heterostructures combining graphene (G) and hexagonal boron nitride (hBN) grains of varying size and distribution. By increasing the hBN grain density from a few percent to 100%, the system evolves from a good conductor to an insulator, with the mobility dropping by orders of magnitude and the sheet resistance reaching the MΩ regime. The Seebeck coefficient is suppressed above 40% mixing, while the thermal conductivity of polycrystalline hBN is found to be on the order of 30-120 Wm(-1) K(-1)...
February 20, 2017: Nano Letters
Florian Huewe, Alexander Steeger, Kalina Kostova, Laurence Burroughs, Irene Bauer, Peter Strohriegl, Vladimir Dimitrov, Simon Woodward, Jens Pflaum
Thermoelectric generator composed of crystalline radical ion salts: The unipolar charge transport along the molecular stacks facilitates complementary p- and n-type organic thermoelectric materials of high electrical conductivity and of 1D electronic structure. The specific power output of 5 mW cm(-2) and the zT > 0.15 below 40 K demonstrate a new field of low-temperature thermoelectric applications unlocked by organic metals.
February 13, 2017: Advanced Materials
Liangying Wang, Bin Dong, Rile Ge, Fengxing Jiang, Jingkun Xu
Organic semiconductors have great potential as flexible thermoelectric materials. A fluorene-based covalent organic framework (FL-COF-1) was designed with the aim of creating an enhanced π-π interaction among the crystalline backbones. By the introduction of fluorene units into the frameworks, the FL-COF-1 had high thermal stability with a BET surface area over 1300 m(2) g(-1). The open frameworks were favorable for doping with iodine and followed with the improved charge carrier mobility. The compressed pellet of I2@FL-COF-1 exhibited a high Seebeck coefficient of 2450 μV K(-1) and power factor of 0...
February 20, 2017: ACS Applied Materials & Interfaces
Haoqi Li, Yaroslav V Aulin, Laszlo Frazer, Eric Borguet, Rohit Kakodkar, Joseph Feser, Yan Chen, Ke An, Dmitriy A Dikin, Fei Ren
Carbonization of nature-inspired polydopamine can yield thin films with high electrical conductivity. Understanding of the structure of carbonized PDA (cPDA) is therefore highly desired. In this study, neutron diffraction, Raman spectroscopy, and other techniques indicate that cPDA samples are mainly amorphous with some short-range ordering and graphite-like structure that emerges with increasing heat treatment temperature. The electrical conductivity and the Seebeck coefficient show different trends with heat treatment temperature, while the thermal conductivity remains insensitive...
February 13, 2017: ACS Applied Materials & Interfaces
Zhen Li, Sage R Bauers, Nirakar Poudel, Danielle M Hamann, Xiaoming Wang, David Choi, Keivan Esfarjani, Li Shi, David C Johnson, Stephen B Cronin
We report cross-plane thermoelectric measurements of misfit layered compounds (SnSe)n(TiSe2)n (n=1,3,4,5), approximately 50nm thick. Metal resistance thermometers are fabricated on the top and bottom of the (SnSe)n(TiSe2)n material to measure the temperature difference and heat transport through the material directly. By varying the number of layers in a supercell, n, we vary the interface density while maintaining a constant global stoichiometry. The Seebeck coefficient measured across the (SnSe)n(TiSe2)n samples was found to depend strongly on the number of layers in the supercell (n)...
February 8, 2017: Nano Letters
Jean-Baptiste Vaney, Gaëlle Delaizir, Bartlomiej Wiendlocha, Janusz Tobola, Eric Alleno, Andrea Piarristeguy, Antonio Pereira Gonçalves, Christine Gendarme, Bernard Malaman, Anne Dauscher, Christophe Candolfi, Bertrand Lenoir
We report on the influence of Se substitution on the electronic band structure and thermoelectric properties (5-523 K) of the solid solution α-As2Te3-xSex (0 ≤ x ≤ 1.5). All of the polycrystalline compounds α-As2Te3-xSex crystallize isostructurally in the monoclinic space group C2/m (No. 12, Z = 4). Regardless of the Se content, chemical analyses performed by scanning electron microscopy and electron probe microanalysis indicate a good chemical homogeneity, with only minute amounts of secondary phases for some compositions...
February 20, 2017: Inorganic Chemistry
Narendar Nasani, Carlos Miguel Oliveira Rocha, Andrei V Kovalevsky, Gonzalo Otero Irurueta, Sascha Populoh, Philipp Thiel, Anke Weidenkaff, Fernando Neto da Silva, Duncan P Fagg
One-dimensional Haldane gap materials, such as the rare earth barium chain nickelates, have received great interest due to their vibrant one-dimensional spin antiferromagnetic character and unique structure. Herein we report how these 1D structural features can also be highly beneficial for thermoelectric applications by analysis of the system CaxBaGd2-xNiO5 0 ≤ x ≤ 0.25. Attractive Seebeck coefficients of 140-280 μV K(-1) at 350-1300 K are retained even at high acceptor-substitution levels, provided by the interplay of low dimensionality and electronic correlations...
February 20, 2017: Inorganic Chemistry
Pinku Roy, Vikram Waghmare, Khagesh Tanwar, Tanmoy Maiti
Oxide based thermoelectric materials have gained some interest in recent times due to their low thermal conductivity, environment friendly nature and high temperature durability. In the present work, the effect of Nb(5+) doping on the thermoelectric properties of BaxSr2-xTiFeO6 based double perovskites was investigated. BaxSr2-xTi0.8Fe0.8Nb0.4O6 (BSTFN) double perovskites with stoichiometric compositions of 0.0 ≤ x ≤ 0.25 were synthesized by the solid-state reaction method. Rietveld refinement powder XRD data confirmed single-phase solid solutions with cubic crystal symmetry for all the BSTFN compositions...
February 8, 2017: Physical Chemistry Chemical Physics: PCCP
Rui-Ning Wang, Guo-Yi Dong, Shu-Fang Wang, Guang-Sheng Fu, Jiang-Long Wang
A gate electrode is usually used to controllably tune the carrier concentrations, further modulating the electrical conductivity and the Seebeck coefficient to obtain the optimum thermoelectric figure of merit (ZT) in two-dimensional materials. On the other hand, it is necessary to investigate how an electric field induced by a gate voltage affects the electronic structures, further determining the thermoelectric properties. Therefore, by using density functional calculations in combination with Boltzmann theory, the thermoelectric properties of bilayer MX2 (M = W, Mo; X = S, Se) with or without a 1 V nm(-1) perpendicular electric field are comparatively investigated...
February 8, 2017: Physical Chemistry Chemical Physics: PCCP
D Beretta, M Massetti, G Lanzani, M Caironi
A new experimental setup for the characterization of flexible micro-thermoelectric generators is reported. The system can measure the power generated and the thermoelectric conversion efficiency of devices under mechanical stresses and deformations, in atmospheric environment and under vacuum, in the temperature interval 293 K-423 K, as a function of the load resistance and of the mechanical pressure, with an uncertainty on the temperature difference of ±0.02 K. The system has been tested on commercial rigid devices and on a custom-made, flexible, proof-of-concept, organic-inorganic hybrid generator made of eight thermocouples...
January 2017: Review of Scientific Instruments
Nis Dam Madsen, Jakob Kjelstrup-Hansen
We present a new method for measuring the piezoresistive gauge factor of a thin-film resistor based on three-point bending. A ceramic fixture has been designed and manufactured to fit a state-of-the-art mechanical testing apparatus (TA Instruments Q800). The method has been developed to test thin-film samples deposited on silicon substrates with an insulating layer of SiO2. The electrical connections to the resistor are achieved through contacts in the support points. This insures that the influence of the electrical contacts is reduced to a minimum and eliminates wire-bonding or connectors attached to the sample...
January 2017: Review of Scientific Instruments
Yuqing Yang, Xiaocun Liu, Xin Liang
We report the enhanced thermoelectric properties of p-type BiCuSeO by tin doping on bismuth sites. Powder X-ray diffraction analysis and Hall measurements indicated effective tin doping in all samples. We found that the doping efficiency of Sn is lower than expected, as seen from the measured carrier concentration. First-principles calculations indicate that the Sn lone pair modifies the band structure at the Fermi level, with the consequent effect observed in the electrical transport and Seebeck coefficient measurements...
February 1, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
Saurabh Singh, Devendra Kumar, Sudhir K Pandey
In the present work, we report the temperature dependent thermopower (α) behavior of La0.75Ba0.25CoO3 compound in the temperature range 300-600 K. Using the Heikes formula, the estimated value of α corresponding to high-spin configuration of Co(3+) and Co(4+) ions is found to be  ∼16 [Formula: see text], which is close to the experimental value, ∼13 [Formula: see text], observed at  ∼600 K. The temperature dependent TE behavior of the compound is studied by combining the WIEN2K and BoltzTrap code...
March 15, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Dan Zhao, Simone Fabiano, Magnus Berggren, Xavier Crispin
Temperature is one of the most important environmental stimuli to record and amplify. While traditional thermoelectric materials are attractive for temperature/heat flow sensing applications, their sensitivity is limited by their low Seebeck coefficient (∼100 μV K(-1)). Here we take advantage of the large ionic thermoelectric Seebeck coefficient found in polymer electrolytes (∼10,000 μV K(-1)) to introduce the concept of ionic thermoelectric gating a low-voltage organic transistor. The temperature sensing amplification of such ionic thermoelectric-gated devices is thousands of times superior to that of a single thermoelectric leg in traditional thermopiles...
January 31, 2017: Nature Communications
Marianne Etzelmüller Bathen, Jacob Linder
We theoretically consider the spin Seebeck effect, the charge Seebeck coefficient, and the thermoelectric figure of merit in superconducting hybrid structures including either magnetic textures or intrinsic spin-orbit coupling. We demonstrate that large magnitudes for all these quantities are obtainable in Josephson-based systems with either zero or a small externally applied magnetic field. This provides an alternative to the thermoelectric effects generated in high-field (~1 T) superconducting hybrid systems, which were recently experimentally demonstrated...
January 31, 2017: Scientific Reports
Mario Culebras, Chungyeon Cho, Michelle Krecker, Ryan Smith, Yixuan Song, Clara Gomez, Andres Cantarero, Jaime C Grunlan
In an effort to produce effective thermoelectric nanocomposites with multiwalled carbon nanotubes (MWCNT), layer-by-layer assembly was combined with electrochemical polymerization to create synergy that would produce a high power factor. Nanolayers of MWCNT stabilized with poly(diallyldimethylammonium chloride) or sodium deoxycholate were alternately deposited from water. Poly(3,4-ethylene dioxythiophene) [PEDOT] was then synthesized electrochemically by using this MWCNT-based multilayer thin film as the working electrode...
January 27, 2017: ACS Applied Materials & Interfaces
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