About this Research Topic
Demands of engineered thermal transport properties are ever increasing for a wide range of modern micro- and nano-devices and materials-based energy technologies. In particular, there is a severe situation due to the rapid progress in the synthesis and processing of materials and devices with a structural characteristic length on the nanometer scales, which are comparable or even smaller than the intrinsic length scales (such as mean free path and wavelength) of basic energy carriers (such as phonons, electrons and photons). Despite advanced approaches for controlling electronic and photonic transport, progress on controlling lattice vibration – the phonons – is far behind. Gaps between the fundamental understanding and technological demands still remain, particularly the behavior of basic energy carriers (such as phonons, electrons, photons) at small scales.
On one hand, the traditional phonon concept plays a critical role in the functionality of many devices including thermoelectrics, thermal management, thermal rectification, etc. For example, as the size of electronic devices shrink smaller and smaller in the past decades, thermal management of these devices has become a bottleneck because of the rapid increase of thermal resistance from interfaces. Phonon interactions generally strongly depend on the length scale, and phonons in nanoscale material show complex behavior. In fundamental research over the past few years significant progress has been made in our knowledge of phonon transport across and along arbitrary interfaces, scattering of phonons by crystal defects, collective phonons, and solid acoustic vibrations when these occur in structures with small physical dimensions.
On the other hand, the traditional treatment of phonons that does not consider the effect of electrons and highly inhomogeneous structures becomes questionable, in particular in some cases where the interaction between phonons and other energy carriers would be significant. Examples are electron/photon-material (phonon) interaction in laser-melting based additive manufacturing process where multiple length scale and multiple time scale process are involved, and phonon-photon interaction in solar energy conversion. Other examples are the interaction between phonons and highly inhomogeneous structures, such as dislocations, grain boundaries, complex interfaces. In addition, heat transfer at extreme conditions can have fundamentally different phenomena and mechanism compared to normal conditions, e.g. high temperature / high pressure phases (such as earth core condition), high heat flux or non-Fourier’s heat conduction.
This Research Topic aims to uncover the ensemble behavior of scale- and time-dependent phonon behavior, not only in single phase materials but also in complex inhomogeneous materials and across interfaces, and advance our understanding in the complex mechanisms determining the thermal transport properties of a variety of micro- and nano-scale materials. From an atomistic and/or multi-scale point of view, potential themes include, but are not limited to:
• computer modeling of phonon transport
• phonon-phonon interactions
• phonon interactions with other energy carriers
• phonon-structure interactions
• robust manipulation of phonon transport with tailored structures and sophisticated approaches
In addition, deep fundamental understanding of thermal transport in various materials with different dimensionality and working conditions relevant to the development of new generation energy systems is particularly of interest.
Keywords: Micro-scale Thermal Transport, Nano-scale Thermal Transport, Phonons, Electrons, Nanomaterials, Energy Nanotechnology
Important Note: All contributions to this Research Topic must be within the scope of the section and journal to which they are submitted, as defined in their mission statements. Frontiers reserves the right to guide an out-of-scope manuscript to a more suitable section or journal at any stage of peer review.