What is it about?
In this work, we demonstrated how via modifications of interfacial chemistry one can control heat transport characteristics of organic/inorganic nanolaminates, i.e. layered soft-hard materials with interfaces separated by a few nanometers. Due to high property contrast between soft and hard components the thermal conductivity is low even with good interfacial bonding and ultra-low with weak bonding. Detailed analysis of heat-carrying thermal waves, i.e., phonons, suggests that the nature of heat flow in these materials is through coherent wave-like transport with each phonon exhibiting multi-interfacial scattering, yet the overall thermal conductivity representing integrated contribution overall phonons, largely behaves as if each interface acts as independent scattering center.
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Photo by Pawel Czerwinski on Unsplash
Why is it important?
Precise control of heat flow in thin film nanolaminates, materials with alternating ultra-thin layers, is critical for various engineering and technological advancements. Understanding how heat travels within these materials and the ability to fine-tune this process holds immense potential across diverse fields. This knowledge is essential for developing next-generation thermoelectric devices, and thermal barrier coatings, as well as for limiting thermal dissipation bottlenecks in microelectronic materials. Furthermore, our demonstration that specific inorganic-organic interfaces are capable of converting longitudinal to transverse waves opens a new road towards the generation of transverse acoustic probes of materials e.g., to characterize interfacial scattering or vibrational dampening.
Perspectives
Pawel Keblinski – senior investigator. My long-term experience with studying heat flow across materials with high-density interfaces unravels a rather consistent observation: Individual phonons scatter with a high degree of coherence at multiple interfaces leading to strong interference effects. However, the overall thermal transport which represents an integrated contribution over all phonons behaves as if each interface acts as an independent scattering center. This allows us to describe thermal transport in high interfacial density materials via the simple model of independent interfacial thermal resistors connected in series. This publication provides yet another example of this common behavior.
Rajan Khadka
Rensselaer Polytechnic Institute
Read the Original
This page is a summary of: On the nature of thermal transport in organic/inorganic nanolaminates, Journal of Applied Physics, April 2024, American Institute of Physics,
DOI: 10.1063/5.0198850.
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