Lorenz Function of Bi2Te3/Sb2Te3 Superlattices

Hinsche, N. F.; Mertig, Ingrid; Zahn, Peter

doi:10.1007/s11664-012-2279-z

Cited by 14 publications

(17 citation statements)

References 32 publications

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“…In Fig. 4 we see in the temperature range 20 -60 K the Lorenz ratio is very close to its standard Sommerfeld value if the thermoelectric effect is considered, suggesting for our Bi 2 in the literature it is reported that Bi 2 Te 3 single crystals may have a dimensionless Lorenz ratio much larger than unity, [14][15][16] however, those abnormalities are due to the bipolar contributions and the emerging temperature is quite different from and much higher than ours. We note the carrier concentration in Fig.…”

Section: Discussionsupporting

confidence: 75%

Experimental determination of phonon thermal conductivity and Lorenz ratio of single-crystal bismuth telluride

et al. 2017

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We use a magnetothermal resistance method to measure the lattice thermal conductivity of a single crystal of Bi 2 Te 3 from 5 to 60 K. We apply a large transverse magnetic field to suppress the electronic thermal conduction while measuring thermal conductivity and electrical resistivity. The lattice thermal conductivity is then calculated by extrapolating the thermal conductivity versus electrical conductivity curve to a zero electrical conductivity value. Our results show that the measured phonon thermal conductivity follows the Δ ⁄ temperature dependence and the Lorenz ratio corresponds to the modified Sommerfeld value in the intermediate temperature range. Our low-temperature experimental data and analysis on Bi 2 Te 3 are an important compliment to previous measurements of Goldsmid [14] and theoretical calculations by Broido et al. [21] at higher temperature 100 -300 K.

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Section: Discussionsupporting

confidence: 75%

Experimental determination of phonon thermal conductivity and Lorenz ratio of single-crystal bismuth telluride

et al. 2017

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“…As Figures 2 and 3 show, L is far from being constant, deviates significantly from L 0 , and the single-band model fails to consistently capture its variation. [57] This occurs because the integrand factor of κ e (Equation (6)) is broader in energy than the integrand factor of σ (see Figure S2 in the Supporting Information), and consequently κ e decreases slower than σ as μ approaches the band edge. [57] This occurs because the integrand factor of κ e (Equation (6)) is broader in energy than the integrand factor of σ (see Figure S2 in the Supporting Information), and consequently κ e decreases slower than σ as μ approaches the band edge.…”

Section: Carrier Scattering and Transportmentioning

confidence: 99%

Accelerated Screening of Thermoelectric Materials by First‐Principles Computations of Electron–Phonon Scattering

Samsonidze

Kozinsky

2018

Advanced Energy Materials

128

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Recent discoveries of new materials for thermoelectric energy conversion are enabled by efficient prediction of the materials' performance from first-principles, without empirically fitted parameters. The novel simplified approach for computing electronic transport properties is described, which achieves good accuracy and transferability while greatly reducing complexity and computation cost compared to the existing methods. The first-principles calculations of the electron-phonon coupling demonstrate that the energy dependence of the electron relaxation time varies significantly with chemical composition and carrier concentration, suggesting that it is necessary to go beyond the commonly used approximations to screen and optimize materials' composition, carrier concentration, and microstructure. The new method is verified using high accuracy computations and validated with experimental data before applying it to screen and discover promising compositions in the space of half-Heusler alloys. By analyzing data trends the effective electron mass is identified as the single best general descriptor determining material' performance. The Lorenz number is computed from first principles and the universality of the Wiedemann-Franz law in thermoelectrics is discussed.

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“…However, no enhancement of the in‐plane TE transport was found under quantum confinement, as suggested within the concept of Hicks and Dresselhaus. As an additional result, the Lorenz function of the

{Bi}_{2} {Te}_{3} / {Sb}_{2} {Te}_{3}

SL and their directional anisotropy were found to be an intricate function of the SL period . Large deviations from the metallic limit

L_{0}

are evident even in the case of large extrinsic charge carrier concentrations, e.g.,

\frac{L_{⊥}}{L_{0}} \sim 2

.…”

Section: Results For Thermoelectric Heterostructuresmentioning

confidence: 86%

“…A detailed analysis for the Lorenz function of the

{Bi}_{2} {Te}_{3} / {Sb}_{2} {Te}_{3}

SL was given in refs. , where the directional anisotropy of L was found to be an intricate function of the SL period. Results for the anisotropic bulk Lorenz function of

{Bi}_{2} {Te}_{3}

are shown in Fig.…”

Section: Transport Theorymentioning

confidence: 99%

Ab initio description of the thermoelectric properties of heterostructures in the diffusive limit of transport

Hinsche

Rittweger

Hölzer

et al. 2015

Physica Status Solidi (a)

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The scope of this review is to present the recent progress in the understanding of the microscopic origin of thermoelectric transport in semiconducting heterostructures and to identify and elucidate mechanisms which could lead to enhanced thermoelectric conversion efficiency. Based on first‐principles calculations a consistent and convenient method is presented to fully describe the thermoelectric properties in the diffusive limit of transport for bulk systems and their associated heterostructures. While fundamentals of the functionality of phonon‐blocking and electron‐transmitting superlattices could be unveiled, we provide also distinct analysis and ideas for thermoelectric enhancement for two archetypical thermoelectric heterostructures based on Bi2Te3/Sb2Te3 and Si/Ge. A focus was on the influence of bulk and interfacial strain, varying charge carrier concentration, temperature, and superlattice periods on the thermoelectric transport properties. Transmission electron micrograph of a 10 Å/50 Å Bi2Te3/Sb2Te3 superlattice. Red and green areas highlight the layered structure. For optimal cross‐plane transport (⊥) phonons (p) are expected to be scattered at the interfaces, while electrons (e−) transmit without losses.

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Lorenz Function of Bi2Te3/Sb2Te3 Superlattices

Cited by 14 publications

References 32 publications

Experimental determination of phonon thermal conductivity and Lorenz ratio of single-crystal bismuth telluride

Experimental determination of phonon thermal conductivity and Lorenz ratio of single-crystal bismuth telluride

Accelerated Screening of Thermoelectric Materials by First‐Principles Computations of Electron–Phonon Scattering

Ab initio description of the thermoelectric properties of heterostructures in the diffusive limit of transport

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