Experimental Evidence of Superdiffusive Thermal Transport in Si<sub>0.4</sub>Ge<sub>0.6</sub> Thin Films

Yao, Fengju; Xia, Shiqiang; Wei, Haoxiang; Zheng, Jiongzhi; Yuan, Ziyuan; Wang, Yusheng; Huang, Baoling; Li, Deyu; Lü, Hong; Xu, Dahai

doi:10.1021/acs.nanolett.2c01050

Cited by 8 publications

(4 citation statements)

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“…However, if the film thickness is smaller or comparable to the average phonon MFP, the thermal transport can be superdiffusive, as demonstrated in previous studies. [64,65] In our case, the average phonon MFP is below 10 nm, which is smaller than most of the films measured in our study. Thus, we do not observe any significant effect of super-diffusive phonon transport here.…”

Section: Phonon Mfp Distribution In Bto and Comparison With Other Com...contrasting

confidence: 73%

Thickness‐Dependent Thermal Conductivity and Phonon Mean Free Path Distribution in Single‐Crystalline Barium Titanate

et al. 2023

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Nanosized perovskite ferroelectrics are widely employed in several electromechanical, photonics, and thermoelectric applications. Scaling of ferroelectric materials entails a severe reduction in the lattice (phonon) thermal conductivity, particularly at sub‐100 nm length scales. Such thermal conductivity reduction can be accurately predicted using the information of phonon mean free path (MFP) distribution. The current understanding of phonon MFP distribution in perovskite ferroelectrics is still inconclusive despite the critical thermal management implications. Here, high‐quality single‐crystalline barium titanate (BTO) thin films, a representative perovskite ferroelectric material, are grown at several thicknesses. Using experimental thermal conductivity measurements and first‐principles based modeling (including four‐phonon scattering), the phonon MFP distribution is determined in BTO. The simulation results agree with the measured thickness‐dependent thermal conductivity. The results show that the phonons with sub‐100 nm MFP dominate the thermal transport in BTO, and phonons with MFP exceeding 10 nm contribute ≈35% to the total thermal conductivity, in significant contrast to previously published experimental results. The experimentally validated phonon MFP distribution is consistent with the theoretical predictions of other complex crystals with strong anharmonicity. This work paves the way for thermal management in nanostructured and ferroelectric‐domain‐engineered systems for oxide perovskite‐based functional materials.

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Section: Phonon Mfp Distribution In Bto and Comparison With Other Com...contrasting

confidence: 73%

Thickness‐Dependent Thermal Conductivity and Phonon Mean Free Path Distribution in Single‐Crystalline Barium Titanate

et al. 2023

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“…等 [24] 图 5 碳纳米管和氮化硼纳米管热阻随尺寸的变化关系 (a) 归一化的热阻随长度的变化关系, 插图为扫描电镜下悬空热桥法的测试装置 [22] ; (b) 碳纳米管的归一化热阻随长度的变化关系(从热阻变化推断出热导率变化为 ) [22] ; (c) 氮化硼纳米管的归一化热阻随长度的发散关系(从而得到 ) [22] Fig. 5.…”

Section: 不同情况下均体现出随长度发散的特性(unclassified

“…2003年, Li和Wang [8] 利用分数维微分方程描述的反常扩散现象, 建起了连接扩散与热传导之图 6 NbSe 3 纳米线和Si 0.4 Ge 0.6 薄膜中的超扩散现象 (a) NbSe 3 纳米线材料体系中的超扩散声子热输运实验发现 [24] ; (b) Si 0.4 Ge 0.6…”

Section: 反常热传导与反常扩散的关系unclassified

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Phononic thermal conduction and thermal regulation in low-dimensional micro-nano scale systems: Nonequilibrium statistical physics problems from chip heat dissipation

Luo,

Ding,

Wei

et al. 2023

Acta Phys. Sin.

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“Heat death”, namely, overheating, which will deteriorate the function of chips and eventually burn the device and has become an obstacle in the roadmap of the semiconductor industry. Therefore, heat dissipation becomes a key issue in further developing semiconductor. Heat conduction in chips encompasses the intricate dynamics of phonon conduction within one-dimensional, two-dimensional materials, as well as the intricate phonon transport through interfaces. In this paper, the research progress of the complexities of phonon transport on a nano and nanoscale in recent three years, especially the size dependent phonon thermal transport and the relationship between anomalous heat conduction and anomalous diffusion are summarized. Further discussed in this paper is the fundamental question within non-equilibrium statistical physics, particularly the necessary and sufficient condition for a given Hamiltonian whose macroscopic transport behavior obeys Fourier’s law. On the other hand, the methods of engineering the thermal conduction, encompassing nanophononic crystals, nanometamaterials, interfacial phenomena, and phonon condensation are also introduced. In order to comprehensively understand the phononic thermal conduction, a succinct overview of phonon heat transport phenomena, spanning from thermal quantization and the phonon Hall effect to the chiral phonons and their intricate interactions with other carriers is presented. Finally, the challenges and opportunities, and the potential application of phonons in quantum information are also discussed.

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Tuning Fe Spin Moment in Fe–N–C Catalysts to Climb the Activity Volcano via a Local Geometric Distortion Strategy

et al. 2022

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As the most promising alternative to platinum‐based catalysts for cathodic oxygen reduction reaction (ORR) in proton exchange membrane fuel cells, further performance enhancement of Fe–N–C catalysts is highly expected to promote their wide application. In Fe–N–C catalysts, the single Fe atom forms a square‐planar configuration with four adjacent N atoms (D4h symmetry). Breaking the D4h symmetry of the FeN4 active center provides a new route to boost the activity of Fe–N–C catalysts. Herein, for the first time, the deformation of the square‐planar coordination of FeN4 moiety achieved by introducing chalcogen oxygen groups (XO2, X = S, Se, Te) as polar functional groups in the Fe–N–C catalyst is reported. The theoretical and experimental results demonstrate that breaking the D4h symmetry of FeN4 results in the rearrangement of Fe 3d electrons and increases spin moment of Fe centers. The efficient spin state manipulation optimizes the adsorption energetics of ORR intermediates, thereby significantly promoting the intrinsic ORR activity of Fe–N–C catalysts, among which the SeO2 modified catalyst lies around the peak of the ORR volcano plot. This work provides a new strategy to tune the local coordination and thus the electronic structure of single‐atom catalysts.

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Experimental Evidence of Superdiffusive Thermal Transport in Si_0.4Ge_0.6 Thin Films

Cited by 8 publications

References 43 publications

Thickness‐Dependent Thermal Conductivity and Phonon Mean Free Path Distribution in Single‐Crystalline Barium Titanate

Thickness‐Dependent Thermal Conductivity and Phonon Mean Free Path Distribution in Single‐Crystalline Barium Titanate

Phononic thermal conduction and thermal regulation in low-dimensional micro-nano scale systems: Nonequilibrium statistical physics problems from chip heat dissipation

Tuning Fe Spin Moment in Fe–N–C Catalysts to Climb the Activity Volcano via a Local Geometric Distortion Strategy

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Experimental Evidence of Superdiffusive Thermal Transport in Si0.4Ge0.6 Thin Films

Cited by 8 publications

References 43 publications

Thickness‐Dependent Thermal Conductivity and Phonon Mean Free Path Distribution in Single‐Crystalline Barium Titanate

Thickness‐Dependent Thermal Conductivity and Phonon Mean Free Path Distribution in Single‐Crystalline Barium Titanate

Phononic thermal conduction and thermal regulation in low-dimensional micro-nano scale systems: Nonequilibrium statistical physics problems from chip heat dissipation

Tuning Fe Spin Moment in Fe–N–C Catalysts to Climb the Activity Volcano via a Local Geometric Distortion Strategy

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Experimental Evidence of Superdiffusive Thermal Transport in Si_0.4Ge_0.6 Thin Films