Measurement of Thermophysical Properties of Carbon Nanotube using a T-type Nano-probe

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(1) Measurements of the thermal conductivity of individual carbon nanotubes (CNT) have been carried out using a T-type nanosensor. The fabrication procedure of the T-type nanosensor was improved and a method was established to make a hot nanofilm with good quality thermal and electrical characteristics.(2) We developed a measurement method to obtain simultaneously the thermal conductivity of a CNT and thermal contact resistance at the junction point of the CNT and hot nanofilm by changing the CNT length at the same junction condition. With the help of Micro-Electro-Mechanical Systems (MEMS), we succeeded to make a nanoprobe with a step-shaped heat sink. However, it was very difficult to reconstruct the T-type nanosensor for the shorter length CNT and simultaneous measurements have not succeeded yet.(3) Besides the measurement of the thermal conductivity of individual CNTs, the thermal conductivity and electrical conductivity of platinum nanofilms with various thicknesses were measured accurately. The measured values for both thermal and electrical conductivity of the nanofilms were less than half of the bulk values as reported previously.(4) The relation between these conductivities and the thickness and grain size of the nanofilms was investigated in detail and compared with the existing theoretical results. It is clarified that the reduction of the conductivities are mainly caused by the scatter of the electrons at the grain boundary. We could explain the reason why the Wiedemann-Frantz law does not hold for the metallic films with nanoscale thicknesses.(5) The reproducibility was confirmed to be very good and the present method to measure the thermal conductivity of CNTs could be applied widely in practical use.