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Daijiro Nozaki, Andreas Lücke, Wolf Gero Schmidt
Destructive Quantum interference (QI) in molecular junctions has attracted much attention in recent years. It can tune the conductance of molecular devices dramatically, which implies numerous potential applications in thermoelectric and switching applications. There are several schemes that address and rationalize QI in single molecular devices. Dimers play a particular role in this respect, since the QI signal may disappear, depending on the dislocation of monomers. In this Letter, we derive a simple rule that governs the occurrence of QI in weakly coupled dimer stacks of both alternant and non-alternant polyaromatic hydrocarbons (PAHs) and extends the Tada-Yoshizawa scheme...
January 20, 2017: Journal of Physical Chemistry Letters
David Kiefer, Liyang Yu, Erik Fransson, Andrés Gómez, Daniel Primetzhofer, Aram Amassian, Mariano Campoy-Quiles, Christian Müller
Poly(ethylene oxide) is demonstrated to be a suitable matrix polymer for the solution-doped conjugated polymer poly(3-hexylthiophene). The polarity of the insulator combined with carefully chosen processing conditions permits the fabrication of tens of micrometer-thick films that feature a fine distribution of the F4TCNQ dopant:semiconductor complex. Changes in electrical conductivity from 0.1 to 0.3 S cm(-1) and Seebeck coefficient from 100 to 60 μV K(-1) upon addition of the insulator correlate with an increase in doping efficiency from 20% to 40% for heavily doped ternary blends...
January 2017: Advanced Science (Weinheim, Baden-Wurttemberg, Germany)
Tamara Ugarte-Avilés, Carlos Manterola, Ricardo Cartes-Velásquez, Tamara Otzen
BACKGROUND: Environmental pollution is a risk factor for cardiorespiratory diseases. Energy generated by thermoelectric power plants (TEPP) represents a relevant source of pollution. The aim of this study was to evaluate the relationship between living near a coal-fired TEPP and the consultation rates for bronchial obstructive crises (BOC) in the province of Concepción, Chile. METHODS: Population-based study. The epidemiological weeks from 2012 to 2014 were analyzed...
January 19, 2017: BMC Public Health
Qinsheng Wang, Cai-Zhen Li, Shaofeng Ge, Jin-Guang Li, Wei Lu, Jiawei Lai, Xuefeng Liu, Junchao Ma, Dapeng Yu, Zhi-Min Liao, Dong Sun
Photodetection with extreme performances in terms of ultrafast response time, broad detection wavelength range, and high sensitivity has wide range of optoelectronic and photonic applications, such as optical communications, interconnects, imaging and remote sensing. Graphene, a typical two-dimensional Dirac semimetal, has shown excellent potential toward high performance photodetector with high operation speed, broadband response and efficient carrier multiplications benefiting from its linear dispersion band structure with high carrier mobility and zero bandgap...
January 18, 2017: Nano Letters
Mouna Gharsallah, Federico Serrano-Sanchez, Norbert M Nemes, Jose Luis Martinez, Jose Antonio Alonso
In competitive thermoelectric devices for energy conversion and generation, high-efficiency materials of both n-type and p-type are required. For this, Bi2Te3-based alloys have the best thermoelectric properties in room temperature applications. Partial replacement of tellurium by selenium is expected to introduce new donor states in the band gap, which would alter electrical conductivity and thermopower. We report on the preparation of n-type Bi2(Te1-xSex)3 solid solutions by a straightforward arc-melting technique, yielding nanostructured polycrystalline pellets...
December 2017: Nanoscale Research Letters
Cynthia Silva Porta, Débora Lemes Dos Santos, Hélio Vieira Bernardes, Bruno Corrêa Bellagamba, Anaí Duarte, Johnny Ferraz Dias, Fernanda Rabaioli da Silva, Mauricio Lehmann, Juliana da Silva, Rafael Rodrigues Dihl
Coal mining generates a considerable amount of waste, which is disposed of in piles or dams near mining sites. As a result, leachates may reach rivers and streams, promoting the wide dispersion of contaminants in solution and as particulate matter. The present study evaluated the cytotoxic, genotoxic, and mutagenic action of surface waters collected around a thermoelectric power plant and the largest mining area in Brazil (Candiota). Four sites in Candiota stream were selected, and samples were collected in winter and summer...
January 6, 2017: Chemosphere
Daniel A Gonçalves, Ana C Soncin, George L Donati, Mirian C Dos Santos
Tungsten coil atomic emission spectrometry (WCAES) is used to determine trace levels of Mn (403.1 nm) and Cr (425.5 nm) in cow placenta. All samples were collected in Ilha Solteira, SP, Brazil. The instrumental setup is based on a tungsten filament extracted from 150 W, 15 V microscope light bulbs, a solid state power supply, fused silica lens, crossed Czerny-Turner spectrograph, and a thermoelectrically cooled charge-coupled device detector. The limits of detection (LOD) and quantification (LOQ) for Cr are 2 and 8 μg L(-1), and 20 and 60 μg L(-1) for Mn, respectively...
January 16, 2017: Biological Trace Element Research
Julian Schaumann, Manuel Loor, Derya Ünal, Anja Mudring, Stefan Heimann, Ulrich Hagemann, Stephan Schulz, Franziska Maculewicz, Gabi Schierning
A systematic study on the microwave-assisted thermolysis of the single source precursor (Et2Sb)2Te (1) in different asymmetric 1-alkyl-3-methylimidazolium- and symmetric 1,3-dialkylimidazolium-based ionic liquids (ILs) reveals the distinctive role of both the anion and the cation in tuning the morphology and microstructure of the resulting Sb2Te3 nanoparticles as evidenced by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), and X-ray photoelectron spectroscopy (XPS)...
January 16, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
Lanling Zhao, Frank Yun Fei, Jun Wang, Funing Wang, Chunlei Wang, Jichao Li, Jiyang Wang, Zhenxiang Cheng, Shixue Dou, Xiaolin Wang
Sulphur doping effects on the crystal structures, thermoelectric properties, density-of-states, and effective mass in Cu1.98SxSe1-x were studied based on the electrical and thermal transport property measurements, and first-principles calculations. The X-ray diffraction patterns and Rietveld refinements indicate that room temperature Cu1.98SxSe1-x (x = 0, 0.02, 0.08, 0.16) and Cu1.98SxSe1-x (x = 0.8, 0.9, 1.0) have the same crystal structure as monoclinic-Cu2Se and orthorhombic-Cu2S, respectively. Sulphur doping can greatly enhance zT values when x is in the range of 0...
January 16, 2017: Scientific Reports
Biao Xu, Tianli Feng, Matthias T Agne, Lin Zhou, Xiulin Ruan, G Jeffery Snyder, Yue Wu
To enhance the performance of thermoelectric materials and enable access to their widespread applications, it is beneficial yet challenging to synthesize hollow nanostructures in large quantities, with high porosity, low thermal conductivity (κ) and excellent figure of merit (z T). Herein we report a scalable (ca. 11.0 g per batch) and low-temperature colloidal processing route for Bi2 Te2.5 Se0.5 hollow nanostructures. They are sintered into porous, bulk nanocomposites (phi 10 mm×h 10 mm) with low κ (0...
January 12, 2017: Angewandte Chemie
Robert L González-Romero, A Antonelli
We used a semi-empirical method to extract carrier relaxation times at different temperatures (τ(T)) in thermoelectric materials from a combination of experimental results and first-principles calculations. The methodology is based on the Boltzmann transport equation formalism within the relaxation time approximation. It can be applied to single crystals and polycrystalline materials. We applied the method to investigate the electronic transport properties of the clathrate compound Ba8Ga16Ge30 type-I. The calculations indicate that the carrier relaxation process in single crystals is dominated by electron-phonon scattering (τ ∝ T(-3/2)), while in polycrystalline materials scattering at grain boundaries dominates (τ ∼ cte)...
January 12, 2017: Physical Chemistry Chemical Physics: PCCP
Soudabeh Mashhadi, Dinh Loc Duong, Marko Burghard, Klaus Kern
Tuning the electron and phonon transport properties of thermoelectric materials by nanostructuring has enabled improving their thermopower figure of merit. Three-dimensional topological insulators, including many bismuth chalcogenides, attract increasing attention for this purpose, as their topologically protected surface states are promising to further enhance the thermoelectric performance. While individual bismuth chalcogenide nanostructures have been studied with respect to their photothermoelectric properties, nanostructured p-n junctions of these compounds have not yet been explored...
January 11, 2017: Nano Letters
Wen-Jie Tan, Yin-Tu Liu, Min Zhu, Tie-Jun Zhu, Xin-Bing Zhao, Xu-Tang Tao, Sheng-Qing Xia
New Mg-containing antimonide Zintl phases, Sr14MgSb11 and Eu14MgSb11, were synthesized from high-temperature solid-state reactions in Ta tubes at 1323 K. Their structures can be viewed as derived from the Ca14AlSb11 structure type, which adopt the tetragonal space group I41/acd (No. 142, Z = 8) with the cell parameters of a = 17.5691(14)/17.3442(11) Å and c = 23.399(4)/22.981(3) Å for the Sr- and Eu-containing compounds, respectively. The corresponding thermoelectric properties were probed, which demonstrated high potential of these compounds as new thermoelectrics for their very low thermal conductivity and moderate Seebeck coefficient...
January 10, 2017: Inorganic Chemistry
Shuankui Li, Tianju Fan, Xuerui Liu, Fusheng Liu, Hong Meng, Yidong Liu, Feng Pan
Novel Bi2Te3/Graphene quantum dot (Bi2Te3/GQDs) hybrid nanosheets with a unique structure that GQDs homogeneously embedded in the Bi2Te3 nanosheet matrix have been synthesized by a simple solution-based synthetic strategy. A significantly reduced thermal conductivity and enhanced powder factor are observed in the pellet composed of Bi2Te3/GQDs nanosheets, which is ascribed to the optimized thermoelectric transport properties of the oxygen-containing Bi2Te3/GQDs interface. Furthermore, by varying the size of GQDs, the thermoelectric performance of Bi2Te3/GQDs hybrid nanostructures could be further enhanced, which could be attributed to the optimization of the density and dispersion manner of GQDs in the Bi2Te3 matrix...
January 10, 2017: ACS Applied Materials & Interfaces
Denis Music, Volker Schnabel, Jozef Bednarcik
Using combinatorial reactive sputtering, we have synthesised Nb-Ru-O thin films on Kapton (polyimide) with the Ru/Nb ratio from 0.5 to 1.1 in a dioxide type of environment. Based on correlative analysis, including synchrotron diffraction experiments and density functional theory, the topology of these amorphous samples is characterised by short metal-oxygen bonds and very pronounced metal-metal interactions within the second coordination shell. We suggest that the role of Nb is within bond length reduction and promotion of quantum confinement, giving rise to an increase in the Seebeck coefficient...
January 6, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Jiawei Zhang, Lirong Song, Steffen Hindborg Pedersen, Hao Yin, Le Thanh Hung, Bo Brummerstedt Iversen
Widespread application of thermoelectric devices for waste heat recovery requires low-cost high-performance materials. The currently available n-type thermoelectric materials are limited either by their low efficiencies or by being based on expensive, scarce or toxic elements. Here we report a low-cost n-type material, Te-doped Mg3Sb1.5Bi0.5, that exhibits a very high figure of merit zT ranging from 0.56 to 1.65 at 300-725 K. Using combined theoretical prediction and experimental validation, we show that the high thermoelectric performance originates from the significantly enhanced power factor because of the multi-valley band behaviour dominated by a unique near-edge conduction band with a sixfold valley degeneracy...
January 6, 2017: Nature Communications
Yufu Lu, Shaoping Chen, Wenchang Wu, Zhengliang Du, Yimin Chao, Jiaolin Cui
In this work the chalcopyrite CuIn3Se5-xTex (x = 0~0.5) with space group through isoelectronic substitution of Te for Se have been prepared, and the crystal structure dilation has been observed with increasing Te content. This substitution allows the anion position displacement ∆u = 0.25-u to be zero at x ≈ 0.15. However, the material at x = 0.1 (∆u = 0.15 × 10(-3)), which is the critical Te content, presents the best thermoelectric (TE) performance with dimensionless figure of merit ZT = 0...
January 6, 2017: Scientific Reports
Jie Zhang, Xiao-Lin Liu, Yanwei Wen, Lu Shi, Rong Chen, Huijun Liu, Bin Shan
Good electronic transport capacity and low lattice thermal conductivity are beneficial for thermoelectric applications. In this study, the potential use as thermoelectric material for the recently synthesized two-dimensional TiS3 monolayer is explored by applying first-principles method combined with Boltzmann transport theory. Our work demonstrates that carrier transport in TiS3 sheet is orientation dependent, caused by the difference of charge density distribution at band edges. Due to a variety of Ti-S bonds with longer lengths, we find TiS3 monolayer show much lower thermal conductivity compared with that of transition metal dichalcogenides such as MoS2...
January 5, 2017: ACS Applied Materials & Interfaces
Taehan Yeo, Hayoung Hwang, Dongjoon Shin, Byungseok Seo, Wonjoon Choi
There is an urgent need to develop a suitable energy source owing to the rapid development of various innovative devices using micro-nanotechnology. The thermopower wave (TW), which produces a high specific power during the combustion of solid fuel inside micro-nanostructure materials, is a unique energy source for unusual platforms that cannot use conventional energy sources. Here, we report on the significant enhancement of hybrid energy generation of pyroelectrics and thermoelectrics from TWs in carbon nanotube (CNT)-PZT (lead zirconate titanate, P(Z0...
January 4, 2017: Nanotechnology
Kyunghan Ahn, Hocheol Shin, Jino Im, Sang Hyun Park, In Chung
We investigate the effect of ZnTe incorporation on PbTe to enhance thermoelectric performance. We report structural, microscopic, and spectroscopic characterizations, ab initio theoretical calculations, and thermoelectric transport properties of Pb0.985Na0.015Te-x% ZnTe (x = 0, 1, 2, 4). We find that the solid solubility limit of ZnTe in PbTe is less than 1 mol %. The introduction of 2% ZnTe in p-type Pb0.985Na0.015Te reduces the lattice thermal conductivity through the ZnTe precipitates at the microscale. Consequently, a maximum thermoelectric figure of merit (ZT) of 1...
January 18, 2017: ACS Applied Materials & Interfaces
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