Seebeck coefficient measurements of lithium isotopes

Surla, V.; Tung, Min‐Che; Xu, Wei; Andruczyk, Daniel; Neumann, M.; Ruzic, D. N.; Mansfield, D. K.

doi:10.1016/j.jnucmat.2011.05.019

Cited by 9 publications

(10 citation statements)

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“…For the ground state and DFPT calculations a "cold smearing" function [20] of width 0.04 Ha is used to improve k-grid convergence. The plane-wave [8], Kendall [9] and Surla et al [10]. The vertical dotted lines denote the temperatures of 9R-to-bcc phase transition and melting point.…”

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confidence: 97%

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First Principles Explanation of the Positive Seebeck Coefficient of Lithium

Verstraete

2014

Phys. Rev. Lett.

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Lithium is one of the simplest metals, with negative charge carriers and a close reproduction of free electron dispersion. Experimentally, however, Li is one of a handful of elemental solids (along with Cu, Ag, Au etc.) where the sign of the Seebeck coefficient (S) is opposite to that of the carrier. This counterintuitive behavior still lacks a satisfactory interpretation. We calculate S fully from firstprinciples, within the framework of P.B. Allen's formulation of Boltzmann transport theory. Here it is crucial to avoid the constant relaxation time approximation, which gives a sign for S which is necessarily that of the carriers. Our calculated S are in excellent agreement with experimental data, up to the melting point. In comparison with another alkali metal Na, we demonstrate that within the simplest non-trivial model for the energy dependency of the electron lifetimes, the rapidly increasing density of states (DOS) across the Fermi energy is related to the sign of S in Li. The exceptional energy dependence of the DOS is beyond the free-electron model, as the dispersion is distorted by the Brillouin Zone edge, a stronger effect in Li than other Aliki metals. The electron lifetime dependency on energy is central, but the details of the electron-phonon interaction are found to be less important, contrary to what has been believed for several decades. Band engineering combined with the mechanism exposed here may open the door to new "ambipolar" thermoelectric materials, with a tunable sign for the thermopower even if either n-or p-type doping is impossible.PACS numbers: 72.15. Jf,72.15.Lh,72.15.Eb,72.10.Di,71.20.Dg Thermoelectricity (TE) has drawn much attention over the past century [1,2] as an effective way of producing electricity from heat energy, or vice versa. In addition to applications in waste heat recovery, the reversible functionality of TE materials also enables heating and refrigeration within the same unit. Spot cooling[3] of computer processors can be achieved with TE devices of small size and without moving parts. The efficiency of current thermoelectric devices is relatively low compared to, e.g., thermal engines, which limits their applications.[1] In the search for a good thermoelectric material, a large Seebeck coefficient (S) is one of the central components in the figure of merit, where it appears squared. Most advances in TE have however targeted the simpler tasks of lowering the thermal conductivity, [4] or optimizing the electron density of states [5]. The magnitude of S is also important in other applications, e.g. for thermal sensors.[6] Though S can be measured straightforwardly in experiment and calculated theoretically within certain approximations, a complete microscopic understanding, and paths for systematic improvement of S are still lacking. The most common approach is to consider a constant averaged relaxation time for the electrons (τ ). The relaxation time approximation (RTA) works in a surprisingly large number of cases, but has little formal justification, and we expos...

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“…For the monovalent metal Li at ambient pressure this is not the case. Lithium exhibits positive S from low to high temperatures, through a martensitic transformation at 77 K [7] and melting at 454 K [8][9][10][11]. This is in contrast to most simple metals, in particular other Alkali metals.…”

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confidence: 99%

First Principles Explanation of the Positive Seebeck Coefficient of Lithium

Verstraete

2014

Phys. Rev. Lett.

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“…Such systems have also been shown to form thermogalvanic cells, where a temperature difference across the cell generated an electrical current [5]. These values are temperature coefficients of the electrode potential (thermogalvanic Seebeck coefficients) and are distinct from the thermoelectric Seebeck coefficient (lithium metal; +0.015 mV•K -1 [6][7][8]). The former are electrochemical phenomena relating to redox and solvation processes, whereas the latter is a phenomenon of electron conductors and semi-conductors.…”

Section: Accepted Manuscriptmentioning

confidence: 99%

“…Heating the electrodes equally, the potential difference was referred to the Seebeck coefficient, and values between -0.8 and +1 mV•K -1 were observed (dependent on the degree of intercalation) [10]. Crucially, the authors assumed the Seebeck coefficient of lithium metal was 0 mV•K -1 [10], presumably because they muddled thermoelectric (+0.015 mV•K -1 [6][7][8]) and thermogalvanic (up to +1.6 mV•K -1 [3]) Seebeck coefficients. Interpretation of these observations focussed upon possible solid-state (thermoelectric) attributes of the intercalation compound, without considering the role of lithium ion intercalation/solvation.…”

Section: Accepted Manuscriptmentioning

confidence: 99%

Temperature effect upon the thermoelectrochemical potential generated between lithium metal and lithium ion intercalation electrodes in symmetric and asymmetric battery arrangements

Black

Harper

Aldous

2018

Electrochemistry Communications

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“…When the thickness of the liquid channel is the same as the wall thickness, the required temperature gradient as a function of magnetic field is plotted in Figure 2 for different material pairs. The thermoelectric power values are taken from [18,19]. For the experiments at Illinois with 0.111 T transverse magnetic field the necessary temperature gradient is around 1.…”

Section: Flow Along Arbitrary Anglementioning

confidence: 99%

Vertical flow in the Thermoelectric Liquid Metal Plasma Facing Structures (TELS) facility at Illinois

Fiflis

Szott

et al. 2015

Journal of Nuclear Materials

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Flowing liquid metal PFCs may offer a solution to the issues faced by solid divertor materials in tokamak plasmas. The Liquid-Metal Infused Trenches (LiMIT) concept of Illinois [1] is a liquid metal plasma facing structure which employs thermoelectric magnetohydrodynamic (TEMHD) effects to self-propel lithium through a series of trenches. The combination of an incident heat flux and a magnetic field provide the driving mechanism. Tests have yielded experimental lithium velocities under different magnetic fields, which agree well with theoretical predictions [2]. The thermoelectric force is expected to overcome gravity and be able to drive lithium flow along an arbitrary direction and the strong surface tension of liquid lithium is believed to maintain the surface when Li flows in open trenches. This paper discusses the behavior of the LiMIT structure when inclined to an arbitrary angle with respect to the horizontal.

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Seebeck coefficient measurements of lithium isotopes

Cited by 9 publications

References 10 publications

First Principles Explanation of the Positive Seebeck Coefficient of Lithium

First Principles Explanation of the Positive Seebeck Coefficient of Lithium

Temperature effect upon the thermoelectrochemical potential generated between lithium metal and lithium ion intercalation electrodes in symmetric and asymmetric battery arrangements

Vertical flow in the Thermoelectric Liquid Metal Plasma Facing Structures (TELS) facility at Illinois

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