Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：International Journal of Heat and Mass Transfer  

The dynamic mechanical processes can notably impact the van der Waals (vdW) interaction at nanoscale contact interface and further interfacial thermal transport, but the experimental study is challenging. Here, by integrating a movable nanoprobe within an electron microscope, we dynamically adjusted the contact and detachment processes of vdW contact between two carbon nanotubes (CNTs), while measuring the thermal contact resistance (TCR) in situ with a nanofabricated thermal sensor. The TCR was found to span approximately two orders of magnitude at the moments when two CNTs just came into contact or detached. Surprisingly, during the initial stage of detachment, we observed that TCR unexpectedly further decreased by 65% instead of increasing. This decrease is attributed to the subtle alteration of exact contact interface in the circumferential direction, induced by the real-time observed rotation during the detachment process. A two-order magnitude difference in TCR for the diverse morphologies in static equilibrium between the same pair of CNTs due to the non-uniformity of the CNT surface structures can also support it. Our work provides valuable insights for dynamically modulating nanoscale interfacial thermal transport in various applications.

DOI： 10.1016/j.ijheatmasstransfer.2024.126047

Web of Science

Scopus

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Communications Materials  

Thermally conductive nanomaterials hold great promise for applications in thermal management. However, the interfaces between nanomaterials can significantly impede heat flow, and a comprehensive understanding of thermal transport across nanoscale contacts is highly desired. Here, by integrating a movable nano-manipulator within an electron microscope with a nanofabricated thermal sensor, we adjusted the contact positions, overlapping length, and crossing angles between two carbon nanotubes (CNTs) as desired, while concurrently measuring the thermal contact resistance (TCR) at the van der Waals junction. The TCR far surpassed that of the studied 6 μm-long CNTs, particularly in contacts affected by inevitable nanoscale surface contamination. The TCR per unit area exhibited significant variations across different contact morphologies, spanning two orders of magnitude even for identical pairs of samples, attributable to structural non-uniformity within the CNTs. This in-situ approach and the notable morphology effects can guide the control of heat at the nanoscale.

DOI： 10.1038/s43246-024-00524-1

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Scopus

Other Link： https://www.nature.com/articles/s43246-024-00524-1

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：International Journal of Heat and Mass Transfer  

The structural non-uniformity in low-dimensional materials, including interfaces and defects, makes it highly desirable to map the thermal property distribution with a high spatial resolution. Meanwhile, eliminating the error of thermal contact resistance at the sample-sensor junction has remained a critical challenge in nanoscale thermal conductivity measurement. Here, we combine the electron beam (EB) heating with two suspended line-shaped heat flux sensors and have achieved the in-situ thermal resistance mapping along a single cup-stacked carbon nanotube (CNT) in a scanning electron microscope (SEM). The CNT is anchored between the two suspended metal lines, and the focused electron beam heats the CNT locally with a nanometer-range spatial resolution, while the two metal lines simultaneously measure the heat fluxes induced by the EB heating. By sweeping the focused EB along the CNT, we can obtain the spatially resolved thermal resistance, from which the true thermal conductivity of the CNT was extracted to be around 40 W/m·K without the thermal contact resistance error. This SEM-based in-situ thermal measurement method can accelerate high-resolution nanomaterials characterization and the elucidation of nanoscale heat transfer.

DOI： 10.1016/j.ijheatmasstransfer.2022.123418

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Scopus

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：American Institute of Physics : AIP  

The thermal conductivity of individual nanomaterials can vary from sample to sample due to the difference in the geometries and internal structures, and thus concurrent structure observation and thermal conductivity measurement at the nanoscale is highly desired but challenging. Here, we have developed an experimental method that allows concurrently the in-situ thermal conductivity measurement and the real-time internal structure observation of a single one-dimensional (1D) material using scanning transmission electron microscopy in a scanning electron microscope (STEM-in-SEM). In this method, the two ends of the 1D nanomaterial are bonded on a tungsten probe and a suspended platinum nanofilm, respectively. The platinum nanofilm serves simultaneously as a heater and a resistance thermometer, ensuring highly sensitive thermal measurements. The platinum nanofilm is fabricated on the edge of the silicon wafer so that the electron beam can transmit through the 1D material and be detected by the STEM detector, which caters for real-time observation of the inner nanostructure. Using this method, we in-situ measured the thermal conductivities of two cup-stacked carbon nanotubes and concurrently observed the internal hollow structures. We found that the sample with more structural disorders had a lower thermal conductivity. Our measurement method can pave the way to the sample24by-sample elucidation of the structure-property relationship for 1D materials.

DOI： 10.1063/5.0079153

Web of Science

Scopus

CiNii Research

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1021/acsami.4c12220

PubMed