Ba
                  8
                  Ga
                  16
                  Sn
                  30
           with type-I clathrate structure: Drastic suppression of heat conduction

Ávila, M. A.; Suekuni, Koichiro; Umeo, Kazunori; Fukuoka, Hiroshi; Yamanaka, Shōji; Takabatake, Toshiro

doi:10.1063/1.2831926

Cited by 113 publications

(157 citation statements)

References 30 publications

Supporting

Mentioning

140

Contrasting

Unclassified

Order By: Relevance

“…Also from equations (4) and (5), when T = 296 K, ω 0 ∼ = 11 THz and x 2 1/2 ω0,T ∼ = 0.12Å. Since in 2D r 2 ω0,T = 2 x 2 ω0,T , this corresponds to a rms guest atom displacement of 0.17Å, which is not far from the values reported previously 18,24 . Solving the Schrödinger equation numerically, the energy levels of this double well potential can be calculated as shown in Fig.…”

Section: Anharmonic Model and Fittingsupporting

confidence: 47%

“…The rattling of guest atoms in the larger of its two structural cages has been confirmed to have close connection to those properties 18,19 . Anharmonic oscillators have also been used as trial models for the rattling phonons to analyze the thermoelectric properties and NMR relaxation behavior of other similar materials [20][21][22] .…”

Section: Introductionmentioning

confidence: 80%

“…The ability to model this behavior with a single set of parameters attests to the lack of irregularity of the cage potential, despite the presence of quasi-random framework substitution. This is apparently due to the Sn-based cage size, providing space for the relatively unconstrained motion of the Ba(2) atoms without allowing for a permanent distortion 18 . Thus, type-I Ba 8 Ga 16 Sn 30 can be viewed as possessing a more or less uniform array of strongly anharmonic local oscillators.…”

Section: −1mentioning

confidence: 99%

See 2 more Smart Citations

NMR relaxation and rattling phonons in the type-I Ba8Ga16Sn30clathrate

2011

View full text Add to dashboard Cite

Atomic motion of guest atoms inside semiconducting clathrate cages is considered as an important source for the glasslike thermal behavior. 69 Ga and 71 Ga Nuclear Magnetic Resonance (NMR) studies on type-I Ba8Ga16Sn30 show a clear low temperature relaxation peak attributed to the influence of Ba rattling dynamics on the framework-atom resonance, with a quadrupolar relaxation mechanism as the leading contribution. The data are analyzed using a two-phonon Raman process, according to a recent theory involving localized anharmonic oscillators. Excellent agreement is obtained using this model, with the parameters corresponding to a uniform array of localized oscillators with very large anharmonicity.

show abstract

Section: Anharmonic Model and Fittingsupporting

confidence: 47%

Section: Introductionmentioning

confidence: 80%

Section: −1mentioning

confidence: 99%

See 1 more Smart Citation

NMR relaxation and rattling phonons in the type-I Ba8Ga16Sn30clathrate

2011

View full text Add to dashboard Cite

show abstract

“…Interestingly, relatively small fillers, such as Sr and Eu in Ge-based clathrates or Ba in Sn-based clathrates, have the off-center rattling character, with fillers tunneling among the off-center-sites. [142][143][144] The unique behaviour results in flat and broad range of optic phonons in the dispersion relations and glass-like κ L at low temperatures. 144 Another good example of rattling modes was found in sodium cobaltate by Voneshen et al 145 The Einstein-like rattling modes were caused by the sodium vacancies.…”

Section: From the Conventional Phonon-phonon Interactions To Nanostrumentioning

confidence: 99%

On the tuning of electrical and thermal transport in thermoelectrics: an integrated theory–experiment perspective

et al. 2016

View full text Add to dashboard Cite

During the last two decades, we have witnessed great progress in research on thermoelectrics. There are two primary focuses. One is the fundamental understanding of electrical and thermal transport, enabled by the interplay of theory and experiment; the other is the substantial enhancement of the performance of various thermoelectric materials, through synergistic optimisation of those intercorrelated transport parameters. Here we review some of the successful strategies for tuning electrical and thermal transport. For electrical transport, we start from the classical but still very active strategy of tuning band degeneracy (or band convergence), then discuss the engineering of carrier scattering, and finally address the concept of conduction channels and conductive networks that emerge in complex thermoelectric materials. For thermal transport, we summarise the approaches for studying thermal transport based on phonon-phonon interactions valid for conventional solids, as well as some quantitative efforts for nanostructures. We also discuss the thermal transport in complex materials with chemical-bond hierarchy, in which a portion of the atoms (or subunits) are weakly bonded to the rest of the structure, leading to an intrinsic manifestation of part-crystalline part-liquid state at elevated temperatures. In this review, we provide a summary of achievements made in recent studies of thermoelectric transport properties, and demonstrate how they have led to improvements in thermoelectric performance by the integration of modern theory and experiment, and point out some challenges and possible directions. INTRODUCTION Thermoelectric (TE) materials are materials that can generate useful electric potentials when subjected to a temperature gradient (known as the Seebeck effect). Conversely, they also transfer heat against the temperature gradient when a current is driven against this potential (known as the Peltier effect). They are promising energy materials with many applications, such as waste heat harvesting, radioisotope TE power generation, and solid state Peltier refrigeration, all of which are driving growing research interest. A key challenge is to improve the TE properties in order to obtain more efficient energy conversion and in turn enable new practical applications. Good TE materials must have excellent electrical transport properties, measured by the TE power factor ( = S 2 σ, where S is the Seebeck coefficient and σ is the electrical conductivity), and also a very low thermal conductivity κ (composed of the electronic contribution κ e , the lattice contribution κ L , and the bipolar contribution κ bi ). Combining the two aspects gives us the dimensionless figure of merit ZT,

show abstract

“…The electronic portion, S 2 ·, is mainly governed by the local electronic structure near the Fermi level, E F . To obtain a large S 1113) These compounds form a narrow bandgap of a few hundred meV near E F , comparable to clathrates 14) and skutterudites. 15) The maximum ZT found among these intermetallic compounds is 0.50 at 773 K for RuGa 2 compound.…”

Section: Introductionmentioning

confidence: 99%

Effects of Transition Metal (TM: Co, Rh, Ni and Pd) Substitution for Ru on Thermoelectric Properties for Intermetallic Compound RuGa<sub>2</sub>

2013

View full text Add to dashboard Cite

The effects of substituting transition metals (TM: Co, Rh, Ni and Pd) on the Ru site with respect to the electrical conductivity and Seebeck coefficient for the binary semiconducting intermetallic compound RuGa 2 have been investigated above room temperature. Only Rh substituted RuGa 2 exhibited a higher electrical conductivity compared with undoped RuGa 2 . The sign of the Seebeck coefficient at 373 K for all doped samples is negative and their magnitudes exhibit rather large values of 150 < «S 373K « < 350 µVK ¹1, indicating that Co, Rh, Ni and Pd work as n-type dopants. However, the sign changes from negative to positive at high temperature. This implies that the effective carrier doping is insufficient to obtain a high efficiency n-type material. To investigate the effect of TM substitution on the electronic density of states, the Korringa-Kohn-Rostoker Green's function method under a coherent potential approximation has been employed. The calculation indicates that the dopant d-states at the conduction band affect the transport properties.

show abstract

Ba 8 Ga 16 Sn 30 with type-I clathrate structure: Drastic suppression of heat conduction

Cited by 113 publications

References 30 publications

NMR relaxation and rattling phonons in the type-I Ba8Ga16Sn30clathrate

NMR relaxation and rattling phonons in the type-I Ba8Ga16Sn30clathrate

On the tuning of electrical and thermal transport in thermoelectrics: an integrated theory–experiment perspective

Effects of Transition Metal (TM: Co, Rh, Ni and Pd) Substitution for Ru on Thermoelectric Properties for Intermetallic Compound RuGa<sub>2</sub>

Contact Info

Product

Resources

About