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Seebeck Coefficient (seebeck + coefficient)
Selected AbstractsThermoelectric properties of RE2,xMxCuO4 oxide sintering bulksELECTRONICS & COMMUNICATIONS IN JAPAN, Issue 12 2008Yusuke Ichino Abstract La2,xSrxCuO4 (LSCO) and Sm2,xCexCuO4 (SCCO) polycrystal bulks with x=0 to 0.10 were made by solid-phase reaction method. From the X-ray diffraction patterns, LSCO and SCCO were confirmed single phase. Seebeck coefficient, resistivity, and heat conductivity decreased with increasing amount of Sr2+ and Ce2+ substitution. We estimated ZT from these values and found that the highest value of ZT=0.034 at 323 K was achieved in the LSCO with x=0.02. As a result, we conclude that LSCO and SCCO showed high thermoelectric properties around room temperature. We can expect RE2,xMxCuO4 will be a very useful material for thermoelectric module operating at room temperature. © 2009 Wiley Periodicals, Inc. Electron Comm Jpn, 91(12): 24,28, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecj.10003 [source] Traversing the Metal-Insulator Transition in a Zintl Phase: Rational Enhancement of Thermoelectric Efficiency in Yb14Mn1,xAlxSb11,ADVANCED FUNCTIONAL MATERIALS, Issue 18 2008Eric S. Toberer Abstract For high temperature thermoelectric applications, Yb14MnSb11 has a maximum thermoelectric figure of merit (zT) of ,1.0 at 1273,K. Such a high zT is found despite a carrier concentration that is higher than typical thermoelectric materials. Here, we reduce the carrier concentration with the discovery of a continuous transition between metallic Yb14MnSb11 and semiconducting Yb14AlSb11. Yb14Mn1-xAlxSb11 forms a solid solution where the free carrier concentration gradually changes as expected from the Zintl valence formalism. Throughout this transition the electronic properties are found to obey a rigid band model with a band gap of 0.5,eV and an effective mass of 3 me. As the carrier concentration decreases, an increase in the Seebeck coefficient is observed at the expense of an increased electrical resistivity. At the optimum carrier concentration, a maximum zT of 1.3 at 1223,K is obtained, which is more than twice that of the state-of-the-art Si0.8Ge0.2 flown by NASA. [source] Complete Characterization of Thermoelectric Materials by a Combined van der Pauw ApproachADVANCED MATERIALS, Issue 38 2010Johannes de Boor Thermoelectric materials can convert waste heat directly into electrical power and represent an important contribution to lessen energy scarcity. Here we present a novel, simple and inexpensive approach for a complete thermoelectric characterization, by which all relevant quantities, like the electrical conductivity, the thermal conductivity, the Seebeck coefficient, and the figure of merit, can be determined directly. [source] Thermoelectric Performance of Epitaxial Thin Films of Layered Cobalt Oxides Grown by Reactive Solid-Phase Epitaxy with Topotactic Ion-Exchange MethodsINTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 4 2007Kenji Sugiura This article reviews high-quality epitaxial film growth of layered cobalt oxides by reactive solid-phase epitaxy (R-SPE) with topotactic ion-exchange methods. Epitaxial film of Na0.8CoO2 was grown on a (0001)-oriented ,-Al2O3 substrate by R-SPE using CoO film as the starting material. The Na0.8CoO2 epitaxial films were converted into high-quality epitaxial films of Sr0.32Na0.21CoO2 and [Ca2CoO3]xCoO2 by topotactic ion-exchange methods. The Sr0.32Na0.21CoO2 film exhibited better stability against moisture than that of the Na0.8CoO2 film, while it retained the good thermoelectric properties of Na0.8CoO2. The [Ca2CoO3]xCoO2 film exhibited a high electrical conductivity of 2.95 × 102 S/cm and a large Seebeck coefficient of +125 ,V/K at 300 K. [source] Fabrication of (Ca1,xLax)MnO3 Ceramics with a High Relative Density and their Power FactorJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 10 2010Hideki Taguchi Perovskite-type (Ca1,xLax)MnO3 powders were synthesized using a Pechini-type polymerized complex route, and (Ca1,x Lax)MnO3 ceramics with a high relative density (85.6%,98.5%) were fabricated using a planetary mill and cold-isostatic pressing (CIP) in order to improve the electrical and thermoelectric properties. The electrical conductivity (,) was independent of both x and the temperature, and the relationship between log ,T vs. 1000/T was linear. The Seebeck coefficient (S) was negative, and the absolute value of the Seebeck coefficient increased with temperature and decreased with increases of x. The highest value of the power factor (S2,) was 3,4 × 10,4 W/(K2·m) for the (Ca0.96La0.04)MnO3 ceramic. [source] Enhanced Properties of Tin(IV) Oxide Based Materials by Field-Activated SinteringJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 6 2003Oana Scarlat The densification of SnO2 (0.9 mol),Sb2O3 (0.1 mol) solid solution without any additives was studied by conventional and field-activated sintering technique (FAST). FAST sintering achieved a relative density value of 92.4% at 1163 K for 10 min versus 61.3% in conventional sintering at 1273 K for 3 h. An abnormal reduction of the IR transmittance and a semiconductor defect structure with only one donor level in the SnO2 energy gap were noticed in the FAST-sintered as compared with the conventionally sintered Sn0.82Sb0.18O2 solid solution. A high charge carrier concentration (i.e., electronic conduction) was shown in the FAST-sintered sample by conductivity measurements and the negative values of the Seebeck coefficient. [source] Influence of Stabilizer Concentration on Transport Behavior and Thermopower of CNT-Filled Latex-Based CompositesMACROMOLECULAR MATERIALS & ENGINEERING, Issue 5 2010Yeon Seok Kim Abstract The influence of the stabilizer/SWNT ratio on the transport behavior of latex-based polymer nanocomposites is examined in an effort to improve electrical conductivity while maintaining or improving the Seebeck coefficient (i.e., thermopower). Results show that phonon and electron transport are significantly affected by tube/tube junctions, and the carrier transport across the junctions can be manipulated by altering the stabilizer concentration. Electrical conductivity of composites containing 10,wt.-% SWNT nearly doubles, becoming greater than 900,S,·,m,1, by changing the SWNT:GA ratio from 1:3 to 10:1, while thermal conductivity and Seebeck coefficient remain relatively constant (near 0.25,W,·,m-K,1 and 40,µV,·,K,1, respectively). [source] Preparation and thermoelectric properties of polycrystalline nonstoichiometric Yb14MnSb11 Zintl compoundsPHYSICA STATUS SOLIDI - RAPID RESEARCH LETTERS, Issue 8-9 2010C. Yu Abstract Polycrystalline nonstoichiometric Yb14MnSb11 compounds have been successfully prepared by modified induction melting and spark plasma sintering. The carrier concentration was finely tuned by changing the elemental ratio of Mn to Sb. Excess Mn decreases the electrical conductivity and increases the Seebeck coefficient. The thermal conductivity of all samples was less than 1.0 W m,1 K,1. The maximum ZT value is 0.35 K at 673 K for Yb14Mn1.05Sb11, significantly higher than that of the stoichiometric Yb14MnSb11 polycrystalline sample. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Highly efficient bismuth telluride doped p-type Pb0.13Ge0.87Te for thermoelectric applicationsPHYSICA STATUS SOLIDI - RAPID RESEARCH LETTERS, Issue 6 2007Yaniv Gelbstein Abstract Bi2Te3 doped p-type Pb0.13Ge0.87Te samples were prepared by hot pressing. We report on very high power factor values of ,30 ,W/cm K2 at 500 °C, as were determined from Seebeck coefficient and electrical resistivity measurements. From dilatometric characterization, the phase transition from the low temperature rhombohedral to the high temperature cubic NaCl structures, takes place at 373 °C. This transition is accompanied by a continuous and gradual change of the lattice parameters, as was observed by hot stage XRD, suggesting a good mechanical durability upon thermal cycling and operating in large thermal gradients. Rhombohedral distortion of the cubic NaCl structure of Pb1,xGex Te upon cooling, characterized by changes in the interaxial angle , and the lattice parameter. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Nanostructured thermoelectric oxides with low thermal conductivityPHYSICA STATUS SOLIDI - RAPID RESEARCH LETTERS, Issue 6 2007A. Weidenkaff Abstract Complex metal oxides, such as e.g. perovskite-type phases are developed as potential functional materials to improve the efficiency of thermoelectric converters. Among those, cobaltates with p-type conductivity and n-type manganates are considered for the realisation of a ceramic thermoelectric converter. Sintered pellets with the composition AMO3,, (A = Ln, RE; M = Co, Mn, Ni, Ti) and "Ca3Co4O9 derivates" were synthesized and characterised concerning their thermoelectric properties in a broad temperature range. It was found that the Seebeck coefficient and the electrical conductivity do not depend on the dimensions of the crystallites, while the heat conductivity can be substantially lowered by decreasing the size of the crystalline domains in these systems. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Synthesis and thermoelectric properties of YbSb2Te4PHYSICA STATUS SOLIDI - RAPID RESEARCH LETTERS, Issue 6 2007Amado S. Guloy Abstract The study of the ternary phase diagram Yb,Sb,Te has led to the synthesis of YbSb2Te4 as a pure phase by way of high energy ball milling followed by annealing, whereas typical high temperature powder metallurgy leads to multiphase sample with impurities of the very stable YbTe. The Hall mobility, Seebeck coefficient, electrical resistivity and thermal conductivity of the layered compound YbSb2Te4 were measured in the range of 20,550 °C. The thermoelectric figure of merit peaks at 525 K and reaches 0.5. Of particular interest is the very low lattice thermal conductivity (as low as a glass) which makes YbSb2Te4 and related compounds promising thermoelectric materials. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Thermoelectric properties of rapid hot pressed polycrystalline Ag1,xPb18SbTe20 synthesized from doping PbTe nanocrystalsPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 1 2010Xingliang Xin Abstract Polycrystalline thermoelectric (TE) materials of n-type and with compositions of Ag1,xPb18SbTe20 (x,=,0, 0.1, 0.2) were prepared by rapid hot pressing from alloy powders, which were obtained by ball milling crystalline ingots. The ingots were synthesized from PbTe nanoparticles, made by solvothermal reactions, and Ag, Sb and Te powders via vacuum-sealed melting in quartz ampoules. Through rapid hot pressing at 748,K for 15,min under 80,MPa, the polycrystalline samples possessed 95% relative densities with the average grain size of 5,µm. The electrical resistivity, Seebeck coefficient and thermal conductivity of the Ag1,xPb18SbTe20 (x,=,0, 0.1, 0.2) samples were measured in the range from room temperature (RT) to 673,K. The thermal conductivity was dramatically decreased, caused by scattering of phonons from grain boundaries and interfaces. By optimizing the values of carrier concentration and carrier transference, the Ag1,xPb18SbTe20 (x,=,0.2) sample achieved a maximum ZT value of 1.019 at 673,K. [source] Phase transitions and transport phenomena in Li0.25Cu1.75Se superionic compoundPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 15 2004M. Kh. Abstract Phase transformation points in Li0.25Cu1.75Se mixed electronic,ionic conductor have been determined by calorimetric, conductometric and thermoelectric measurements. The phase transformation (PT) from triclinic to monoclinic occurs at 403,413 K. At 503,515 K the monoclinic phase is followed by a rhombohedral modification. Both of these PTs are accompanied by drops on the calorimetric curve. At about 653 K observed anomalies in the temperature dependencies of the ionic conductivity, of the chemical diffusion coefficient and the jump of the ionic Seebeck coefficient have been induced by the PT to hexagonal phase. Neutron diffraction studies reveal the cubic structure of Li0.25Cu1.75Se compound (with space group Fm3m) at 773 K. The corresponding PT causes anomalies in the electrical and diffusion properties at 703,713 K. Cu ions are statistically distributed over tetrahedral and trigonal voids in an Fm3m cage; lithium ions randomly occupy 32(f) positions. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Synthesis and Seebeck coefficient of nanostructured phosphorus-alloyed bismuth telluride thick filmsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 11 2008Jian Zhou Abstract Phosphorous-alloyed Bi2Te3 thick films have been prepared by electrochemical deposition. The average grain size of the films was calculated to be 14-26 nm based on Scherrer's equation. The effect of P on the Seebeck coefficient of thermoelectric P-alloyed Bi2Te3 thick film was investigated. The results show that P-alloyed thick film has n-type conductivity with the Seebeck coefficient of -35 ,V/K. The correlation between P site occupancy in the crystal and the Seebeck coefficient was discussed. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] A Promising Approach to Enhanced Thermoelectric Properties Using Carbon Nanotube NetworksADVANCED MATERIALS, Issue 4 2010Chuizhou Meng Enhanced Seebeck coefficients and power factors , important for the conversion of heat to electrical energy , are obtained in polyaniline/carbon nanotube (PANI/CNT) composites in which PANI coats CNT networks (see figure). The values are several times larger than those of either of the individual components. This new approach has potential for synthesizing high-performance thermoelectric materials. [source] | |||||||||||||