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Title: Effect of ceramic dispersion on thermoelectric properties of nano-ZrO{sub 2}/CoSb{sub 3} composites

Abstract

In the present work, nano-ZrO{sub 2}/CoSb{sub 3} composites were fabricated by milling ZrO{sub 2} and CoSb{sub 3} powders and hot pressing at different sintering temperatures. For the prepared compacts, the phase purity, microstructure, and temperature-dependent thermoelectric properties were characterized. The effect of nano-ZrO{sub 2} dispersion on composite electrical conductivity and thermal conductivity is strictly clarified by comparing the transport properties of the nondispersed and dispersed CoSb{sub 3} at identical porosity, so that the effect of porosity on thermoelectric parameters could be eliminated. The effect of the insulating inclusion itself on transport properties is also considered and eliminated using effective media theories. It is clearly verified that charge carrier scattering and phonon scattering occur simultaneously to lower the electrical conductivity and the thermal conductivity of CoSb{sub 3} due to the introduction of nano-ZrO{sub 2} inclusions. The investigated composites show higher electrical conductivity due to existence of metallic Sb and lower thermal conductivity because of nanodispersion. At the ranges of high measuring temperature (673-723 K) and low porosity (6%-9%), the ratio of electrical conductivity to thermal conductivity of the dispersed CoSb{sub 3} is higher than that of nondispersed CoSb{sub 3}, and the dimensionless figure of merit (ZT) of the composite could probablymore » be improved at these ranges with the enhanced ratio of electrical conductivity to thermal conductivity and Seebeck coefficient, which is assumed to be increased by a potential barrier scattering.« less

Authors:
; ; ; ; ; ; ;  [1];  [2]
  1. Institute of Materials Research, German Aerospace Center (DLR), D-51170 Cologne (Germany)
  2. (KTH), SE-10044 Stockholm (Sweden)
Publication Date:
OSTI Identifier:
20982705
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 101; Journal Issue: 4; Other Information: DOI: 10.1063/1.2561628; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ANTIMONY ALLOYS; CERAMICS; CHARGE CARRIERS; CHARGED-PARTICLE TRANSPORT; COBALT ALLOYS; COMPOSITE MATERIALS; ELECTRIC CONDUCTIVITY; HOT PRESSING; MICROSTRUCTURE; MILLING; NANOSTRUCTURES; POROSITY; POWDERS; SEEBECK EFFECT; SINTERING; TEMPERATURE DEPENDENCE; TEMPERATURE RANGE 0400-1000 K; THERMAL CONDUCTIVITY; THERMOELECTRIC PROPERTIES; ZIRCONIUM OXIDES

Citation Formats

He, Zeming, Stiewe, Christian, Platzek, Dieter, Karpinski, Gabriele, Mueller, Eckhard, Li, Shanghua, Toprak, Muhammet, Muhammed, Mamoun, and Materials Chemistry Division, Royal Institute of Technology. Effect of ceramic dispersion on thermoelectric properties of nano-ZrO{sub 2}/CoSb{sub 3} composites. United States: N. p., 2007. Web. doi:10.1063/1.2561628.
He, Zeming, Stiewe, Christian, Platzek, Dieter, Karpinski, Gabriele, Mueller, Eckhard, Li, Shanghua, Toprak, Muhammet, Muhammed, Mamoun, & Materials Chemistry Division, Royal Institute of Technology. Effect of ceramic dispersion on thermoelectric properties of nano-ZrO{sub 2}/CoSb{sub 3} composites. United States. doi:10.1063/1.2561628.
He, Zeming, Stiewe, Christian, Platzek, Dieter, Karpinski, Gabriele, Mueller, Eckhard, Li, Shanghua, Toprak, Muhammet, Muhammed, Mamoun, and Materials Chemistry Division, Royal Institute of Technology. Thu . "Effect of ceramic dispersion on thermoelectric properties of nano-ZrO{sub 2}/CoSb{sub 3} composites". United States. doi:10.1063/1.2561628.
@article{osti_20982705,
title = {Effect of ceramic dispersion on thermoelectric properties of nano-ZrO{sub 2}/CoSb{sub 3} composites},
author = {He, Zeming and Stiewe, Christian and Platzek, Dieter and Karpinski, Gabriele and Mueller, Eckhard and Li, Shanghua and Toprak, Muhammet and Muhammed, Mamoun and Materials Chemistry Division, Royal Institute of Technology},
abstractNote = {In the present work, nano-ZrO{sub 2}/CoSb{sub 3} composites were fabricated by milling ZrO{sub 2} and CoSb{sub 3} powders and hot pressing at different sintering temperatures. For the prepared compacts, the phase purity, microstructure, and temperature-dependent thermoelectric properties were characterized. The effect of nano-ZrO{sub 2} dispersion on composite electrical conductivity and thermal conductivity is strictly clarified by comparing the transport properties of the nondispersed and dispersed CoSb{sub 3} at identical porosity, so that the effect of porosity on thermoelectric parameters could be eliminated. The effect of the insulating inclusion itself on transport properties is also considered and eliminated using effective media theories. It is clearly verified that charge carrier scattering and phonon scattering occur simultaneously to lower the electrical conductivity and the thermal conductivity of CoSb{sub 3} due to the introduction of nano-ZrO{sub 2} inclusions. The investigated composites show higher electrical conductivity due to existence of metallic Sb and lower thermal conductivity because of nanodispersion. At the ranges of high measuring temperature (673-723 K) and low porosity (6%-9%), the ratio of electrical conductivity to thermal conductivity of the dispersed CoSb{sub 3} is higher than that of nondispersed CoSb{sub 3}, and the dimensionless figure of merit (ZT) of the composite could probably be improved at these ranges with the enhanced ratio of electrical conductivity to thermal conductivity and Seebeck coefficient, which is assumed to be increased by a potential barrier scattering.},
doi = {10.1063/1.2561628},
journal = {Journal of Applied Physics},
number = 4,
volume = 101,
place = {United States},
year = {Thu Feb 15 00:00:00 EST 2007},
month = {Thu Feb 15 00:00:00 EST 2007}
}
  • CoSb{sub 3} thin films are deposited on conducting glass substrates (FTO) by electrodeposition at different bath temperatures (60°C, 70°C and 80°C) and the resulting influence of the bath temperature on the structure, morphology and electrical properties of films is investigated. X-ray diffraction confirms the formation of CoSb{sub 3} phase in the films. Scanning electron microscopy reveals that different morphologies ranging from branched nano-flakes to nano-needles evolve as bath temperature increases. It is concluded that a growth temperature of 80°C is suitable for producing CoSb{sub 3} films with such properties that show potential feasibility for thermoelectric applications.
  • The microstructural evolution in mullite/zirconia and mullite/alumina/zirconia composites after different duration heat treatments at 1570/sup 0/C has been investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive X-ray microanalysis. The effect of free alumina on microstructural and mechanical parameters is also reported.
  • The effect of Al/sub 2/O/sub 3/ and (Ti or Si) C additions on various properties of a (Y)TZP (yttria-stabilized tetragonal zirconia polycrystal)-Al/sub 2/O/sub 3/-(Ti or Si)C ternary composite ceramic were investigated for developing a zirconia-based ceramic stronger than SiC at high temperatures. Adding Al/sub 2/O/sub 3/ to (Y)TZP improved transverse rupture strength and hardness to decreased fracture toughness. This binary composite ceramic revealed a rapid loss of strength with increasing temperature. Adding TiC to the binary ceramic suppressed the decrease in strength at temperatures above 1573K. The residual tensile stress induced by the differential thermal expansion between ZrO/sub 2/ andmore » TiC therefore must have inhibited the t- /omega/-mZrO/sub 2/ martensitic transformation. It was concluded that a continuous skeleton of TiC prevented grain-boundary sliding between ZrO/sub 2/ and Al/sub 2/O/sub 3/.« less
  • We synthesized Bi 2Te 3 and CoSb 3 based nanomaterials and their thermoelectric, structural, and vibrational properties analyzed to assess and reduce ZT-limiting mechanisms. The same preparation and/or characterization methods were applied in the different materials systems. Single-crystalline, ternary p-type Bi 15Sb 29Te 56, and n-type Bi 38Te 55Se 7 nanowires with power factors comparable to nanostructured bulkmaterialswere prepared by potential-pulsed electrochemical deposition in a nanostructured Al 2O 3 matrix. p-type Sb 2Te 3, n-type Bi 2Te 3, and n-type CoSb 3 thin films were grown at room temperature using molecular beam epitaxy and were subsequently annealed at elevated temperatures.more » It yielded polycrystalline, single phase thin films with optimized charge carrier densities. In CoSb 3 thin films the speed of sound could be reduced by filling the cage structure with Yb and alloying with Fe yielded p-type material. Bi 2(Te 0.91Se 0.09) 3/SiC and (Bi 0.26Sb 0.74) 2Te 3/SiC nanocomposites with low thermal conductivities and ZT values larger than 1 were prepared by spark plasma sintering. Nanostructure, texture, chemical composition, as well as electronic and phononic excitations were investigated by X-ray diffraction, nuclear resonance scattering, inelastic neutron scattering, M ossbauer spectroscopy, and transmission electron microscopy. Furthermore, for Bi 2Te 3 materials, ab-initio calculations together with equilibrium and non-equilibrium molecular dynamics simulations for point defects yielded their formation energies and their effect on lattice thermal conductivity, respectively. Current advances in thermoelectric Bi 2Te 3 and CoSb 3 based nanomaterials are summarized. Advanced synthesis and characterization methods and theoreticalmodelingwere combined to assess and reduce ZT-limiting mechanisms in these materials.« less
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