Miniature Semiconductor Thermoelectric Devices

Rowe, D.M.

doi:10.1201/9781420049718.ch35

Cited by 181 publications

(273 citation statements)

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“…One of the main disadvantages of existing TE generators is their low conversion efficiency, which is mainly due to the low efficiency of the TE materials embedded in them. Commercially available bismuth telluride (Bi 2 Te 3 ) based TE devices have an efficiency of ∼10% [1] and are one of the best materials for Peltier coolers and TE devices operating near room temperature [2,3].…”

Section: Introductionmentioning

confidence: 99%

Electrochemical deposition of bismuth telluride thick layers onto nickel

Lei

Ryder

Koukharenko

et al. 2016

Electrochemistry Communications

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Bismuth telluride (Bi 2 Te 3 ) is the currently best performing thermoelectric (TE) material in commercial TE devices for refrigeration and waste heat recovery up to 200°C. Up to 800 μm thick, compact, uniform and stoichiometric Bi 2 Te 3 films were synthesized by pulsed electrodeposition from 2M nitric acid baths containing bismuth and tellurium dioxide on 1cm 2 nickel (Ni) substrates at average film growth rates of ~50 μm/hour. Pre-treatment of the Ni substrate was found to significantly enhance the adhesion of Bi 2 Te 3 material onto Ni whilst pulsed electrodeposition was used to increase the compactness of the material. To maintain a homogeneous composition across the thickness of the films, a sacrificial Bi 2 Te 3 anode was employed. All deposits produced were n-type with a Seebeck coefficient of up to -80μV/K and an electrical conductivity of ~330 S/cm at room temperature.

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Section: Introductionmentioning

confidence: 99%

Electrochemical deposition of bismuth telluride thick layers onto nickel

Lei

Ryder

Koukharenko

et al. 2016

Electrochemistry Communications

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“…1,2 This however is contingent on fabricating materials with higher thermoelectric efficiencies than currently available. Bismuth-telluride-based alloys are currently the best commercially available thermoelectric materials for applications at room temperatures.…”

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confidence: 99%

Electrochemical Formation of p-Type Bi_0.5Sb_1.5Te₃Thick Films onto Nickel

Lei

Burton

Nandhakumar

2017

J. Electrochem. Soc.

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Bismuth-telluride-based alloys are currently the best commercially available thermoelectric materials for applications at room temperatures. Up to 150 micron thick layers of bismuth antimony telluride (Bi 0.5 Sb 1.5 Te 3 ) were directly deposited onto nickel by either potenstiostatic or potentiodynamic electrodeposition. Cyclic voltammetry was employed to identify the optimal deposition potential. The films were characterized by scanning electron microscopy, energy dispersive X-rays and X-ray diffraction. The p-type films were found to be well adherent, uniform and stoichiometric with a high power factor of 2.3 × 10 −4 W m −1 K −2 at film growth rates of up to 40 μm h −1 . © The Author(s) 2017. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any medium, provided the original work is properly cited. [DOI: 10.1149/2.1151704jes] All rights reserved.Manuscript submitted December 15, 2016; revised manuscript received February 6, 2017. Published February 14, 2017 Power harvesting from thermoelectric (TE) devices is seen as a highly promising route toward sustainable energy, as electricity can be generated from waste heat using the Seebeck effect.1,2 This however is contingent on fabricating materials with higher thermoelectric efficiencies than currently available. Bismuth-telluride-based alloys are currently the best commercially available thermoelectric materials for applications at room temperatures. 3Whilst a wide range of fabrication techniques 4,5 exists for the production of bismuth telluride compounds, including molecular organic vapor phase deposition (MOVPD), molecular beam epitaxy (MBE), liquid phase epitaxy (LPE) and bulk powder synthesis, these methods have proven to be quite costly and/or difficult to realize. Electrochemical deposition on the other hand provides an attractive low-cost, room temperature and scalable route and bismuth telluride alloys prepared in this way are a striking example of the type of high-quality thermoelectric materials that can be prepared in this way. 6 Whilst there have been many reports on the electrochemical deposition of n-type Bi 2 Te 3 , 7,8 the preparation of p-type bismuth antimony telluride (Bi 0.5 Sb 1.5 Te 3 )10-12 has received very little attention with film thicknesses not exceeding 20 microns. The realization of functional TE devices for commercial applications however relies on incorporating the materials as both n and p-type thick films, e.g. such as those encountered in vertical TE designs on vehicle exhaust pipes. 8,13,14 The main challenge with the electrodeposition of p-type Bi 0.5 Sb 1.5 Te 3 has been attributed to the low solubility of antimony in aqueous electrolytes which results in insufficient amounts of Sb 3+ . This makes the preparation of thick layers of Bi 0.5 Sb 1.5 Te 3 extremely challenging as it requires fast deposition rates (∼10 μm/hour) to make the process commerci...

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“…The optic and acoustic phonon modes exchange their characters when they interact due to avoided crossing, which leads to the formation of the hybrid modes [34]. The degree of hybridization between the filler and the framework phononic modes, and thus the avoided crossing properties, depend significantly on the filler [35,36]. A weak coupling between the filler and the framework results in independent vibrations of the filler atoms, i.e.…”

Section: Results and Discussion A Phonon Dispersion And Phonon mentioning

confidence: 99%

Phonon dynamics in type-VIII silicon clathrates: Beyond the rattler concept

2017

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Clathrates can form a type of guest-host solid structures that, unlike most crystalline solids, have very low thermal conductivity. It is generally thought that the guest atoms caged inside the host framework act as "rattlers" and induce lattice dynamics disorders responsible for the small thermal conductivity. We performed a systematic study of the lattice dynamical properties of type VIII clathrates with alkali and alkaline earth guests, i.e. X 8 Si 46 (X=Na, K, Rb, Cs, Ca, Sr, Ba). The energy dependent participation ratio (PR) and the atomic participation ratio of phonon modes extracted from density functional theory calculations revealed that the rattler concept is not adequate to describe the effect of fillers as they manifest strong hybridization with the framework. For the case of heavy fillers, such as Rb, Sr, Cs, and Ba, phonon bandgap was formed between the acoustic and optical branches. The calculated PR indicated that the fillers suppress the acoustic phonon modes and change the energy transport mechanism from propagative to diffusive or localized resulting in "phonon-glass" characteristics. This effect is stronger for the heavy fillers. Furthermore, in all cases, the guest insertion depressed the phonon bandwidth, reduced the Debye temperature, and reduced the phonon group velocity, all of which should lead to reduction of the thermal conductivity. I. INTRODUCTIONClathrate semiconductors are among novel materials with excellent potential to fulfill the phonon-glass electron-crystal (PGEC) concept. These caged structure materials contain guest atoms which are believed to vibrate at very low frequencies inside the cages and scatter the acoustic phonons of the host and thereby lower the thermal conductivity. It is frequently stated that because the filler-host atomic bonding is weak, the presence of the fillers usually has little effect on the host electronic bands, so that the filler reduces the thermal conductivity without impairing the electrical properties [1]. Although, the rattler hypothesis is the most popular mechanism in explaining the behavior of the clathrates and skutterudites, the impact of the fillers on the lattice dynamical properties is not fully explained and yet remains an open question. Some observations such as the localized modes seen in inelastic neutron scattering and heat capacity measurements support empirically the rattling concept in skutterudites [2,3]. However, the inelastic neutron scattering (INS) experiments on Fe 4 Sb 12 containing Ce or Le filler indicated evidences for the existence of coherent propagation of filler phonons [4], which is inconsistent with the rattler concept. The INS studies of phonon dynamics in (La,Ce)Fe 4 Sb 12 skutterudites revisited the picture of rattling fillers in a host cage and the microscopic mechanism responsible for the scattering of heat carrier phonons. Furthermore, the results from the theoretical studies are also contradicting. The rattling behavior implies a resonant scattering resulting from the weak interaction between the filler ...

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Miniature Semiconductor Thermoelectric Devices

Cited by 181 publications

References 13 publications

Electrochemical deposition of bismuth telluride thick layers onto nickel

Electrochemical deposition of bismuth telluride thick layers onto nickel

Electrochemical Formation of p-Type Bi_0.5Sb_1.5Te₃Thick Films onto Nickel

Phonon dynamics in type-VIII silicon clathrates: Beyond the rattler concept

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Miniature Semiconductor Thermoelectric Devices

Cited by 181 publications

References 13 publications

Electrochemical deposition of bismuth telluride thick layers onto nickel

Electrochemical deposition of bismuth telluride thick layers onto nickel

Electrochemical Formation of p-Type Bi0.5Sb1.5Te3Thick Films onto Nickel

Phonon dynamics in type-VIII silicon clathrates: Beyond the rattler concept

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Electrochemical Formation of p-Type Bi_0.5Sb_1.5Te₃Thick Films onto Nickel