Coordination-Resolved Electron Spectrometrics

Liu, Xinjuan; Zhang, Xi; Bo, Maolin; Li, Lei; Tian, Hongwei; Nie, Yanguang; Sun, Yi; Xu, Shiqing; Wang, Yan; Zheng, Weitao; Sun, Chang Q.

doi:10.1021/cr500651m

Cited by 134 publications

(99 citation statements)

References 475 publications

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“…23 This effect deepens the potential well of trapping in the surface skin. 24 Electrons in the relaxed region are more localized because of the depressed potential well of trapping, which lowers the conductivity in the surface region due to boundary scattering. 25,26 Bond shortening and strengthening provide perturbation to the local potential, and this undercoordination effect should also have an important impact on the phonon transport dynamics.…”

Section: Theoretical Model and Derivationmentioning

confidence: 99%

Ultra-low thermal conductivity of two-dimensional phononic crystals in the incoherent regime

et al. 2018

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Two-dimensional silicon phononic crystals have attracted extensive research interest for thermoelectric applications due to their reproducible low thermal conductivity and sufficiently good electrical properties. For thermoelectric devices in high-temperature environment, the coherent phonon interference is strongly suppressed; therefore phonon transport in the incoherent regime is critically important for manipulating their thermal conductivity. On the basis of perturbation theory, we present herein a novel phonon scattering process from the perspective of bond order imperfections in the surface skin of nanostructures. We incorporate this strongly frequency-dependent scattering rate into the phonon Boltzmann transport equation and reproduce the ultra low thermal conductivity of holey silicon nanostructures. We reveal that the remarkable reduction of thermal conductivity originates not only from the impediment of low-frequency phonons by normal boundary scattering, but also from the severe suppression of high-frequency phonons by surface bond order imperfections scattering. Our theory not only reveals the role of the holey surface on the phonon transport, but also provide a computation tool for thermal conductivity modification in nanostructures through surface engineering.

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Section: Theoretical Model and Derivationmentioning

confidence: 99%

Ultra-low thermal conductivity of two-dimensional phononic crystals in the incoherent regime

et al. 2018

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“…For instance, compression stores energy into a substance by shortening and stiffening all bonds with possible plastic deformation when the compression is relieved. Tension does the opposite [14]. The following formulates bond relaxation in length and energy under stimuli P and T [12]:…”

Section: Dimer Bond: An Isolated Oscillatormentioning

confidence: 99%

Water's phase diagram: From the notion of thermodynamics to hydrogen-bond cooperativity

Zhang

Sun

Yan

et al. 2015

Progress in Solid State Chemistry

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“…An elastic Coulomb-levitation mechanism is responsible not only for ice slipperiness and water hydrophobicity but also for low friction of dry solid such as graphite, nitrides, oxides, and fluorides because of the presence of nonbonding electrons [33]. Generally, bond order loss shortens and stiffens the bond between undercoordinated atoms by up to 12% for a flat skin of an fcc geometry, which enhances the bond energy by 45% and depresses the atomic cohesive energy by 62% for a metal such as gold and copper [37]. The enhanced bond energy raises the skin elasticity by 67% and lowers the local meting temperature by 63% [13].…”

Section: A Common Supersolid Skin Covers Both Water and Icementioning

confidence: 99%

From ice superlubricity to quantum friction: Electronic repulsivity and phononic elasticity

Zhang

Huang

et al. 2015

Friction

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Superlubricity means non-sticky and frictionless when two bodies are set contacting motion. Although this occurrence has been extensively investigated since 1859 when Faraday firstly proposed a quasiliquid skin on ice, the mechanism behind the superlubricity remains uncertain. This report features a consistent understanding of the superlubricity pertaining to the slipperiness of ice, self-lubrication of dry solids, and aqueous lubricancy from the perspective of skin bond-electron-phonon adaptive relaxation. The presence of nonbonding electron polarization, atomic or molecular undercoordination, and solute ionic electrification of the hydrogen bond as an addition, ensures the superlubricity. Nonbond vibration creates soft phonons of high magnitude and low frequency with extraordinary adaptivity and recoverability of deformation. Molecular undercoordination shortens the covalent bond with local charge densification, which in turn polarizes the nonbonding electrons making them localized dipoles. The locally pinned dipoles provide force opposing contact, mimicking magnetic levitation and hovercraft. O:H−O bond electrification by aqueous ions has the same effect of molecular undercoordination but it is throughout the entire body of the lubricant. Such a Coulomb repulsivity due to the negatively charged skins and elastic adaptivity due to soft nonbonding phonons of one of the contacting objects not only lowers the effective contacting force but also prevents charge from being transited between the counterparts of the contact. Consistency between theory predictions and observations evidences the validity of the proposal of interface elastic Coulomb repulsion that serves as the rule for the superlubricity of ice, wet and dry frictions, which also reconciles the superhydrophobicity, superlubricity, and supersolidity at contacts.

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Coordination-Resolved Electron Spectrometrics

Cited by 134 publications

References 475 publications

Ultra-low thermal conductivity of two-dimensional phononic crystals in the incoherent regime

Ultra-low thermal conductivity of two-dimensional phononic crystals in the incoherent regime

Water's phase diagram: From the notion of thermodynamics to hydrogen-bond cooperativity

From ice superlubricity to quantum friction: Electronic repulsivity and phononic elasticity

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