Anomalously low electronic thermal conductivity in metallic vanadium dioxide

Lee, Sangwook; Hippalgaonkar, Kedar; Yang, Fan; Hong, Jiawang; Ko, Changhyun; Suh, Joonki; Liu, Kai; Wang, Kevin; Urban, Jeffrey J.; Zhang, Xiang; Dames, Chris; Hartnoll, Sean A.; Delaire, Olivier; Wu, Junqiao

doi:10.1126/science.aag0410

Cited by 354 publications

(289 citation statements)

References 76 publications

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“…In the past two decades, many excellent TE materials [24,35,42,47,65,442,443] have been identified and developed, showing increased diversity rather than the conventional Bi 2 Te 3 -, PbTe-, and SiGe-based materials. [28,85] Recently, anomalously low κ e was achieved in metallic vanadium dioxide in the vicinity of its metal-insulator transition, [447] which provides a potential opportunity to decouple the κ e and σ. Based on the understanding of these physical essences, various effective strategies are introduced in Section 3.…”

Section: Summary and Perspectivementioning

confidence: 99%

High Performance Thermoelectric Materials: Progress and Their Applications

Yang

Chen

Dargusch

et al. 2017

Advanced Energy Materials

656

434

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Thermoelectric (TE) materials have the capability of converting heat into electricity, which can improve fuel efficiency, as well as providing robust alternative energy supply in multiple applications by collecting wasted heat, and therefore, assisting in finding new energy solutions. In order to construct high performance TE devices, superior TE materials have to be targeted via various strategies. The development of high performance TE devices can broaden the market of TE application and eventually boost the enthusiasm of TE material research. This review focuses on major novel strategies to achieve high‐performance TE materials and their applications. Manipulating the carrier concentration and band structures of materials are effective in optimizing the electrical transport properties, while nanostructure engineering and defect engineering can greatly reduce the thermal conductivity approaching the amorphous limit. Currently, TE devices are utilized to generate power in remote missions, solar–thermal systems, implantable or/wearable devices, the automotive industry, and many other fields; they are also serving as temperature sensors and controllers or even gas sensors. The future tendency is to synergistically optimize and integrate all the effective factors to further improve the TE performance, so that highly efficient TE materials and devices can be more beneficial to daily lives.

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Section: Summary and Perspectivementioning

confidence: 99%

High Performance Thermoelectric Materials: Progress and Their Applications

Yang

Chen

Dargusch

et al. 2017

Advanced Energy Materials

656

434

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confidence: 99%

Thermal Conductivity during Phase Transitions

et al. 2018

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high thermal conductivity are widely used in heat dissipating applications, [3][4][5][6] while the materials with low thermal conductivity [7][8][9][10] are used as thermal insulation. In particular, thermal conductivity is one of the key parameters in thermoelectric materials and also plays an important role in other energy materials such as solar cells and battery materials. Therefore, evaluation of thermal conductivity is very fundamental and important, but the measurement could sometimes be a great challenge. The understanding and measurement of thermal conductivity are especially questionable for materials with phase transitions while these materials exist extensively and have been exploited for different fields including thermoelectrics, [11][12][13][14] solid state memory, [15] and switches. [16] The energy exchange during phase transitions gives rise to a few fundamental questions on thermal conductivity measurement. Transient measurement methods such as laser flash method (LFA) are commonly used to measure thermal diffusivity λ and the thermal conductivity κ is calculated using the equation of κ = C P × d × λ (d is the density and C P is the heat capacity), due to the significant advantages of transient methods over the steady-state measurements. [17] It is well known that the heat capacity (C P ) can be significantly increased during phase transition because the extra energy is required to transit a low temperature structure to a high temperature structure in materials (see Figure 1a). Recent study also shows that the thermal diffusivity (λ) can be lowered in some phase transition materials such as Cu 2 Se, Cu 2 S, and Ag 2 S, but is almost unaffected by phase transition in Ag 2 Se (see Figure 1b). The understanding on thermal conductivity during phase transitions is not established yet. This leads to the thermal conductivity calculated with different heat capacity values highly deviated, although the measured heat capacity and thermal diffusivity are quite close or similar. For example, a dramatic decrease in κ in Cu 2 Se second-order phase transition is reported by Liu et al. [11] when using the Dulong-Petit value for heat capacity, while an increased κ is reported by Brown et al. [18] after adding the contribution of phase transition to heat capacity (Figure 1c). Such different κ values change the thermoelectric figure of merit (zT) from a moderate value of 0.6 to an extremely high value of 2.3 (which can be considered as a breakthrough in thermoelectrics) in Cu 2 Se during its second-order phase transition. More confusingly, the heat capacity ( Figure 1a) and electrical transport measurements ( Figure S6, Supporting Information) clearly show that Cu 2 S and Ag 2 S have first-order phase transitions with Thermal conductivity is a very basic property that determines how fast a material conducts heat, which plays an important and sometimes a dominant role in many fields. However, because materials with phase transitions have been widely used recently, understanding and measuring temperature-dependent t...

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“…Measurements using the suspended-pad method were described in previous reports. 20,22,23 All measurements were performed under low vacuum (<10 À6 Torr) with radiation shield. (See the details of devices fabrication process and measurements in supplementary material.…”

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confidence: 99%

Variable range hopping electric and thermoelectric transport in anisotropic black phosphorus

Liu

Choe

Chen

et al. 2017

Applied Physics Letters

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Black phosphorus (BP) is a layered semiconductor with a high mobility of up to $1000 cm 2 V À1 s À1 and a narrow bandgap of $0.3 eV, and shows potential applications in thermoelectrics. In stark contrast to most other layered materials, electrical and thermoelectric properties in the basal plane of BP are highly anisotropic. To elucidate the mechanism for such anisotropy, we fabricated BP nanoribbons ($100 nm thick) along the armchair and zigzag directions, and measured the transport properties. It is found that both the electrical conductivity and Seebeck coefficient increase with temperature, a behavior contradictory to that of traditional semiconductors. The three-dimensional variable range hopping model is adopted to analyze this abnormal temperature dependency of electrical conductivity and Seebeck coefficient. The hopping transport of the BP nanoribbons, attributed to high density of trap states in the samples, provides a fundamental understanding of the anisotropic BP for potential thermoelectric applications. Published by AIP Publishing. [http://dx

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Anomalously low electronic thermal conductivity in metallic vanadium dioxide

Cited by 354 publications

References 76 publications

High Performance Thermoelectric Materials: Progress and Their Applications

High Performance Thermoelectric Materials: Progress and Their Applications

Thermal Conductivity during Phase Transitions

Variable range hopping electric and thermoelectric transport in anisotropic black phosphorus

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