Temperature-Dependent Mean Free Path Spectra of Thermal Phonons Along the <i>c</i>-Axis of Graphite

Zhang, Hang; Chen, Xiangwen; Jho, Young‐Dahl; Minnich, Austin J.

doi:10.1021/acs.nanolett.5b04499

Cited by 83 publications

(93 citation statements)

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“…Encased 10-layer graphene has a thermal conductivity larger than 1000 W/(m K) (Jang, et al, 2013), and the supported graphene of 34 layers is found to fully recover to the bulk value of graphite (Sadeghi, et al, 2013). The large thickness required to ensure a higher thermal conductivity of encased and supported graphene is probably due to the long mean free paths of phonons in graphite along the crossplane direction, which was revealed recently by MD simulations (Wei, et al, 2014b) and confirmed by experimental measurements (Fu, et al, 2015;Zhang, et al, 2016).…”

Section: E1 Thermal Conductivity Of Supported 2-d Materialsmentioning

confidence: 59%

Colloquium: Phononic thermal properties of two-dimensional materials

et al. 2018

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Following the emergence of many novel two-dimensional (2-D) materials beyond graphene, interest has grown in exploring implications for fundamental physics and practical applications, ranging from electronics, photonics, phononics, to thermal management and energy storage. In this Colloquium, we first summarize and compare the phonon properties, such as phonon dispersion and relaxation time, of pristine 2-D materials with single layer graphene to understand the role of crystal structure and dimension on thermal conductivity. We then compare the phonon properties, contrasting idealized 2-D crystals, realistic 2-D crystals, and 3-D crystals, and synthesizing this to develop a physical picture of how the sample size of 2-D materials affects their thermal conductivity. The effects of geometry, such as number of layers, and nanoribbon width, together with the presence of defects, mechanical strain, and substrate interactions, on the thermal properties of 2-D materials are discussed. Intercalation affects both the group velocities and phonon relaxation times of layered crystals and thus tunes the thermal conductivity along 2 both the through-plane and basal-plane directions. We conclude with a discussion of the challenges in theoretical and experimental studies of thermal transport in 2-D materials. The rich and special phonon physics in 2-D materials make them promising candidates for exploring novel phenomena such as topological phonon effects and applications such as phononic quantum devices.

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Section: E1 Thermal Conductivity Of Supported 2-d Materialsmentioning

confidence: 59%

Colloquium: Phononic thermal properties of two-dimensional materials

et al. 2018

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“…Since the induced temperature oscillation depends on the thermal properties of the samples, TDTR is an accurate approach to measure the thermal conductivity of nanostructures. [49][50][51] In this study, we used a 1/e 2 laser radius of 10 lm, a modulation frequency of 10 MHz, and a total laser power of $40 mW to limit the steady state temperature rise to <10 K. The thermal conductivities of Cr 1-x Sc x N were then derived by comparing the TDTR measurements to the calculations of a thermal model. 52 In the analysis, we used the thickness of Al film derived from picosecond acoustics, 53 the heat capacity of CrN and ScN from their bulk values, 54,55 and the heat capacity of Cr 1-x Sc x N alloy films estimated from virtual crystal approximation.…”

Section: E Thermoelectric Properties Measurementsmentioning

confidence: 99%

Experimental and theoretical investigation of Cr1-xScxN solid solutions for thermoelectrics

Kerdsongpanya

Sun

Eriksson

et al. 2016

Journal of Applied Physics

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Articles you may be interested inThe ScN-and CrN-based transition-metal nitrides have recently emerged as a novel and unexpected class of materials for thermoelectrics. These materials constitute well-defined model systems for investigating mixing thermodynamics, phase stability, and band structure aiming for property tailoring. Here, we demonstrate an approach to tailor their thermoelectric properties by solid solutions. The trends in mixing thermodynamics and densities-of-states (DOS) of rocksalt-Cr 1-x Sc x N solid solutions (0 x 1) are investigated by first-principles calculations, and Cr 1-x Sc x N thin films are synthesized by magnetron sputtering. Pure CrN exhibits a high power factor, 1.7 Â 10 À3 W m À1 K À2 at 720 K, enabled by a high electron concentration thermally activated from N vacancies. Disordered rocksalt-Cr 1-x Sc x N solid solutions are thermodynamically stable, and calculated DOS suggest the possibility for power-factor improvement by Sc3d orbital delocalization on Cr3d electrons giving decreasing electrical resistivity, while localized Cr3d orbitals with a large DOS slope may yield an improved Seebeck coefficient. Sc-rich solid solutions show a large improvement in power factor compared to pure ScN, and all films have power factors above that expected from the rule-of-mixture. These results corroborate the theoretical predictions and enable tailoring and understanding of structure-transport-property correlations of Cr 1-x Sc x N. Published by AIP Publishing.

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“…Phonon MFPs of typical crystalline semiconductors such as Si, GaN, and graphite are on the order of tens of nanometers to micrometers. [10][11][12] Accordingly, evident phonon interference effects were observed by both experimental work and theoretical analysis on phonon transport across superlattices, i.e., alternative nanoscopic layers of epitaxially bonded semiconductors such as GaAs and AlAs. 2,[13][14][15] For amorphous materials such as amorphous silica (aSiO 2 ), however, the traveling phonons can be diffusely scattered by the disordered structure, which significantly limits the phonon MFP.…”

Section: Introductionmentioning

confidence: 99%

Phonon interference in crystalline and amorphous confined nanoscopic films

Liang

Wilson

Keblinski

2017

Journal of Applied Physics

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Using molecular dynamics phonon wave packet simulations, we study phonon transmission across hexagonal (h)-BN and amorphous silica (a-SiO 2 ) nanoscopic thin films sandwiched by two crystalline leads. Due to the phonon interference effect, the frequency-dependent phonon transmission coefficient in the case of the crystalline film (Sijh-BNjAl heterostructure) exhibits a strongly oscillatory behavior. In the case of the amorphous film (Sija-SiO 2 jAl and Sija-SiO 2 jSi heterostructures), in spite of structural disorder, the phonon transmission coefficient also exhibits oscillatory behavior at low frequencies (up to $1.2 THz), with a period of oscillation consistent with the prediction from the two-beam interference equation. Above 1.2 THz, however, the phonon interference effect is greatly weakened by the diffuse scattering of higher-frequency phonons within an a-SiO 2 thin film and at the two interfaces confining the a-SiO 2 thin film. Published by AIP Publishing.

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Temperature-Dependent Mean Free Path Spectra of Thermal Phonons Along the c-Axis of Graphite

Abstract: Heat conduction in graphite has been studied for decades because of its exceptionally large thermal anisotropy. While the bulk thermal conductivities along the in-plane and cross-plane

Cited by 83 publications

References 50 publications

Colloquium: Phononic thermal properties of two-dimensional materials

Colloquium: Phononic thermal properties of two-dimensional materials

Experimental and theoretical investigation of Cr1-xScxN solid solutions for thermoelectrics

Phonon interference in crystalline and amorphous confined nanoscopic films

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