The Experts below are selected from a list of 15213 Experts worldwide ranked by ideXlab platform
Séverine Gomès - One of the best experts on this subject based on the ideXlab platform.
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Scanning Thermal microscopy on samples of varying effective Thermal conductivities and identical flat surfaces
Journal of Applied Physics, 2020Co-Authors: Eloise Guen, Pierre-olivier Chapuis, R. Rajkumar, Philipp Dobson, Gordon B Mills, Jonathan Weaver, Séverine GomèsAbstract:We propose an approach for the characterization of scanning Thermal microscopy (SThM) probe response using a sample with silicon dioxide steps. The chessboard-like sample provides a series of nine surfaces made of the same material, with identical roughness, but consisting of different thicknesses of silica layers standing on a single silicon wafer. The nine regions have different effective Thermal conductivities, allowing calibration of SThM probes within a given set of surface conditions. A key benefit is the possibility of comparing the spatial resolution and the sensitivity to vertical inhomogeneities of the sample for different probes. A model is provided to determine the Thermal Contact area and Contact Thermal Resistance from the experimental data. The results underline that ballistic heat conduction can be significant in crystalline substrates below the top thin films, especially for film thicknesses lower than 200 nm and effective Thermal Contact radius lower than 200 nm. They also highlight the sensitivity of SThM to ultrathin films, as well as the substrate below micrometric films under in-air conditions but not when in vacuum. This work advances quantitative nanometer-scale Thermal metrology, where usual photoThermal methods are more difficult to implement.
Eloise Guen - One of the best experts on this subject based on the ideXlab platform.
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Scanning Thermal microscopy on samples of varying effective Thermal conductivities and identical flat surfaces
Journal of Applied Physics, 2020Co-Authors: Eloise Guen, Pierre-olivier Chapuis, R. Rajkumar, Philipp Dobson, Gordon B Mills, Jonathan Weaver, Séverine GomèsAbstract:We propose an approach for the characterization of scanning Thermal microscopy (SThM) probe response using a sample with silicon dioxide steps. The chessboard-like sample provides a series of nine surfaces made of the same material, with identical roughness, but consisting of different thicknesses of silica layers standing on a single silicon wafer. The nine regions have different effective Thermal conductivities, allowing calibration of SThM probes within a given set of surface conditions. A key benefit is the possibility of comparing the spatial resolution and the sensitivity to vertical inhomogeneities of the sample for different probes. A model is provided to determine the Thermal Contact area and Contact Thermal Resistance from the experimental data. The results underline that ballistic heat conduction can be significant in crystalline substrates below the top thin films, especially for film thicknesses lower than 200 nm and effective Thermal Contact radius lower than 200 nm. They also highlight the sensitivity of SThM to ultrathin films, as well as the substrate below micrometric films under in-air conditions but not when in vacuum. This work advances quantitative nanometer-scale Thermal metrology, where usual photoThermal methods are more difficult to implement.
Juekuan Yang - One of the best experts on this subject based on the ideXlab platform.
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measurement of the intrinsic Thermal conductivity of a multiwalled carbon nanotube and its Contact Thermal Resistance with the substrate
Small, 2011Co-Authors: Juekuan Yang, Scott W Waltermire, Alfred A Zinn, Yang Yang, Timothy Gutu, Yunfei ChenAbstract:The intrinsic Thermal conductivity of an individual carbon nanotube and its Contact Thermal Resistance with the heat source/sink can be extracted simultaneously through multiple measurements with different lengths of the tube between the heat source and the heat sink. Experimental results on a 66-nm-diameter multiwalled carbon nanotube show that above 100 K, Contact Thermal Resistance can contribute up to 50% of the total measured Thermal Resistance; therefore, the intrinsic Thermal conductivity of the nanotube can be significantly higher than the effective Thermal conductivity derived from a single measurement without eliminating the Contact Thermal Resistance. At 300 K, the Contact Thermal Resistance between the tube and the substrate for a unit area is 2.2 × 10(-8) m(2) K W(-1) , which is on the lower end among several published data. Results also indicate that for nanotubes of relatively high Thermal conductance, electron-beam-induced gold deposition at the tube-substrate Contacts may not reduce the Contact Thermal Resistance to a negligible level. These results provide insights into the long-lasting issue of the Contact Thermal Resistance in nanotube/nanowire Thermal conductity measurements and have important implications for further understanding Thermal transport through carbon nanotubes and using carbon nanotube arrays as Thermal interface materials.
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Contact Thermal Resistance between individual multiwall carbon nanotubes
Applied Physics Letters, 2010Co-Authors: Juekuan Yang, Scott W Waltermire, Yunfei Chen, Alfred A ZinnAbstract:We report on experimental measurements of Contact Thermal Resistance between individual carbon nanotubes. Results indicate that the Contact Thermal conductance can increase by nearly two orders of magnitude (from 10−8 to 10−6 W/K) as the Contact area increases from a cross Contact to an aligned Contact. Normalization with respect to the Contact area leads to normalized Contact Thermal Resistance on the order of 10−9 m2 K/W at room temperature, one order of magnitude lower than that from a molecular dynamics simulation in literature. These results should have important implications in the design of carbon nanotube-polymer composites for tunable Thermal properties.
Jing Liu - One of the best experts on this subject based on the ideXlab platform.
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finned heat pipe assisted low melting point metal pcm heat sink against extremely high power Thermal shock
Energy Conversion and Management, 2018Co-Authors: Xiaohu Yang, Jing LiuAbstract:Abstract In this paper, a finned heat pipe assisted passive heat sink based on a newly emerging high performance phase change material (PCM), the low melting point metal (LMPM), was developed for Thermal buffering of high power electronics which works intermittently with heat generation rate up to 1000 W (10 W/cm2). Firstly, Thermal performances of the PCM heat sink under different Thermal shocks (from 200 W to 1000 W) were experimentally evaluated, in comparison with that of an organic PCM which has similar melting point. It was found that, the former one can prolong the working duration 1.4–2.4 times that of the latter one. Then, the performance of the heat sink was improved through reducing the Contact Thermal Resistance and by increasing the fin number. Furtherly, an air cooling radiator was configured to accelerate the solidification process of the PCM module, which makes it capable of maintaining its highest temperature below 85 °C under 1000 W periodic Thermal shock (10 min on and 15 min off). Moreover, energy dispersive spectrometer (EDS) analysis was conducted to verify the compatibility of the LMPM PCM and the structural materials. Finally, a simplified numerical model was developed and validated for the currently constructed finned heat pipe assisted LMPM PCM heat sink, which can be much helpful for future practical Thermal design and optimization of this kind of Thermal buffering module.
Yunfei Chen - One of the best experts on this subject based on the ideXlab platform.
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measurement of the intrinsic Thermal conductivity of a multiwalled carbon nanotube and its Contact Thermal Resistance with the substrate
Small, 2011Co-Authors: Juekuan Yang, Scott W Waltermire, Alfred A Zinn, Yang Yang, Timothy Gutu, Yunfei ChenAbstract:The intrinsic Thermal conductivity of an individual carbon nanotube and its Contact Thermal Resistance with the heat source/sink can be extracted simultaneously through multiple measurements with different lengths of the tube between the heat source and the heat sink. Experimental results on a 66-nm-diameter multiwalled carbon nanotube show that above 100 K, Contact Thermal Resistance can contribute up to 50% of the total measured Thermal Resistance; therefore, the intrinsic Thermal conductivity of the nanotube can be significantly higher than the effective Thermal conductivity derived from a single measurement without eliminating the Contact Thermal Resistance. At 300 K, the Contact Thermal Resistance between the tube and the substrate for a unit area is 2.2 × 10(-8) m(2) K W(-1) , which is on the lower end among several published data. Results also indicate that for nanotubes of relatively high Thermal conductance, electron-beam-induced gold deposition at the tube-substrate Contacts may not reduce the Contact Thermal Resistance to a negligible level. These results provide insights into the long-lasting issue of the Contact Thermal Resistance in nanotube/nanowire Thermal conductity measurements and have important implications for further understanding Thermal transport through carbon nanotubes and using carbon nanotube arrays as Thermal interface materials.
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Contact Thermal Resistance between individual multiwall carbon nanotubes
Applied Physics Letters, 2010Co-Authors: Juekuan Yang, Scott W Waltermire, Yunfei Chen, Alfred A ZinnAbstract:We report on experimental measurements of Contact Thermal Resistance between individual carbon nanotubes. Results indicate that the Contact Thermal conductance can increase by nearly two orders of magnitude (from 10−8 to 10−6 W/K) as the Contact area increases from a cross Contact to an aligned Contact. Normalization with respect to the Contact area leads to normalized Contact Thermal Resistance on the order of 10−9 m2 K/W at room temperature, one order of magnitude lower than that from a molecular dynamics simulation in literature. These results should have important implications in the design of carbon nanotube-polymer composites for tunable Thermal properties.