Determining conductivity and mobility values of individual components in multiphase composite Cu1.97Ag0.03Se

Day, Tristan; Zeier, Wolfgang G.; Brown, David R.; Melot, Brent C.; Snyder, G. Jeffrey

doi:10.1063/1.4897435

Cited by 25 publications

(12 citation statements)

References 25 publications

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“…The enhanced S values of PbSe/PbTe samples compared to that of PbSe samples appear to arise from the energy barriers at the interfaces, including the precipitate/matrix interfaces and grain boundaries. Moreover, some reports showed that impurity phases (Pb impurity phases in our case) can influence the transport properties within a semiconductor. ,,, An in-depth discussion of this is included in the next section. It should be emphasized that the increase in σ for the bulk PbSe/PbTe samples starts at 523 K, which is identical to the temperature at which the rate of increase of S decreases, as shown in Figure c (this is discussed in detail later).…”

Section: Resultsmentioning

confidence: 94%

“…These systems are similar to those in the present study because PbSe/PbTe samples have an excess of Pb atoms, Te-rich PbSe/PbTe precipitates with a wide size distribution, and many grain boundaries. Using effective medium theory, Day et al successfully separated conductivity and mobility of independent phases and showed an impurity phase can severely influence TE transport properties. About an application of the effective medium theory to multiple-component TE materials, Gelbstein et al , explained well in some papers.…”

Section: Resultsmentioning

confidence: 99%

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Spinodally Decomposed PbSe-PbTe Nanoparticles for High-Performance Thermoelectrics: Enhanced Phonon Scattering and Unusual Transport Behavior

et al. 2016

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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 PbSe0.5Te0.5 reaches a high figure of merit of 1.85. The spinodally decomposed nanoparticles permit our thermoelectric material to have extremely low lattice thermal conductivity and a high power factor as a result of nanostructuring, electronic optimization, insertion of an impurity phase and phase change in local areas. We propose that this interesting concept would be one of the promising approaches that overcome limitation arising from the fact that most parameters in the figure of merit are closely correlated.

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Section: Resultsmentioning

confidence: 94%

Section: Resultsmentioning

confidence: 99%

Spinodally Decomposed PbSe-PbTe Nanoparticles for High-Performance Thermoelectrics: Enhanced Phonon Scattering and Unusual Transport Behavior

et al. 2016

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“…In order to minimize the influence of secondary phases on the thermoelectric properties, nominal compositions were chosen to be very close to the stable points and due to the lever rule, the amount of secondary phases is small and their effect can thus be neglected. For small amounts of secondary phases, it can be shown using effective medium theory that the first order effect on electrical and thermal transport properties is proportional to the volume fraction of impurity [20]. Thus for 1% volume fraction the measured transport properties should only be 1% in error.…”

Section: Thermoelectric Properties Of Optimized Compositionsmentioning

confidence: 98%

Temperature dependent solubility of Yb in Yb–CoSb3 skutterudite and its effect on preparation, optimization and lifetime of thermoelectrics

Tang

Chen

Snyder

2015

Journal of Materiomics

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Although filled skutterudites are actively being developed for automotive waste heat recovery the compositions considered available are limited. Typically synthesis conditions are chosen with slight excess filling element to produce filled skutterudites at the 'filling fraction limit', traditionally considered to be a single value that depends only on the elements involved (e.g. filling element, Co/Fe ratio). The filling fraction limit is often debated and thought perhaps to vary with processing method. This work opens up a new dimension of available compositions by showing that the 'filling fraction limit' is a thermodynamic quantity that for Yb varies by a factor of 5 depending on annealing temperature and nominal composition. As the filling element controls the electronic doping in these semiconductors this study not only enables optimization of thermoelectric properties using thermodynamic control rather than non-equilibrium processing conditions (reaching zT ¼ 1.3 at 850 K without nanostructures) but it also predicts dopant precipitation effects after extended use. The novel phase diagram approach used here should be easily applied to other ternary thermoelectric materials to uncover similar phenomena. Thus skutterudite material with the optimized thermoelectric composition can be produced from a range of nominal compositions with appropriate annealing.

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“…To describe the effects of having a mixture of two materials (in this case the experimental material and air), effective medium theory (EMT) is used to analyze the electrical and thermal conductivity of porous materials. Generalized EMT developed by Bruggeman and Landauer, and described by Stroud was used to explain the low field Hall effect by Cohen .…”

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confidence: 99%

Melt‐Centrifuged (Bi,Sb)₂Te₃: Engineering Microstructure toward High Thermoelectric Efficiency

et al. 2018

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Microstructure engineering is an effective strategy to reduce lattice thermal conductivity (κ ) and enhance the thermoelectric figure of merit (zT). Through a new process based on melt-centrifugation to squeeze out excess eutectic liquid, microstructure modulation is realized to manipulate the formation of dislocations and clean grain boundaries, resulting in a porous network with a platelet structure. In this way, phonon transport is strongly disrupted by a combination of porosity, pore surfaces/junctions, grain boundaries, and lattice dislocations. These collectively result in a ≈60% reduction of κ compared to zone melted ingot, while the charge carriers remain relatively mobile across the liquid-fused grains. This porous material displays a zT value of 1.2, which is higher than fully dense conventional zone melted ingots and hot pressed (Bi,Sb) Te alloys. A segmented leg of melt-centrifuged Bi Sb Te and Bi Sb Te could produce a high device ZT exceeding 1.0 over the whole temperature range of 323-523 K and an efficiency up to 9%. The present work demonstrates a method for synthesizing high-efficiency porous thermoelectric materials through an unconventional melt-centrifugation technique.

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Determining conductivity and mobility values of individual components in multiphase composite Cu1.97Ag0.03Se

Cited by 25 publications

References 25 publications

Spinodally Decomposed PbSe-PbTe Nanoparticles for High-Performance Thermoelectrics: Enhanced Phonon Scattering and Unusual Transport Behavior

Spinodally Decomposed PbSe-PbTe Nanoparticles for High-Performance Thermoelectrics: Enhanced Phonon Scattering and Unusual Transport Behavior

Temperature dependent solubility of Yb in Yb–CoSb3 skutterudite and its effect on preparation, optimization and lifetime of thermoelectrics

Melt‐Centrifuged (Bi,Sb)₂Te₃: Engineering Microstructure toward High Thermoelectric Efficiency

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Determining conductivity and mobility values of individual components in multiphase composite Cu1.97Ag0.03Se

Cited by 25 publications

References 25 publications

Spinodally Decomposed PbSe-PbTe Nanoparticles for High-Performance Thermoelectrics: Enhanced Phonon Scattering and Unusual Transport Behavior

Spinodally Decomposed PbSe-PbTe Nanoparticles for High-Performance Thermoelectrics: Enhanced Phonon Scattering and Unusual Transport Behavior

Temperature dependent solubility of Yb in Yb–CoSb3 skutterudite and its effect on preparation, optimization and lifetime of thermoelectrics

Melt‐Centrifuged (Bi,Sb)2Te3: Engineering Microstructure toward High Thermoelectric Efficiency

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Melt‐Centrifuged (Bi,Sb)₂Te₃: Engineering Microstructure toward High Thermoelectric Efficiency