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

(1)使用t型纳米传感器对单个碳纳米管（CNT）的导热系数进行了测量。改进了t型纳米传感器的制备工艺，建立了一种制备热电特性优良的热纳米膜的方法。(2)我们开发了一种测量方法，通过改变碳纳米管的长度，可以同时获得碳纳米管与热纳米膜连接点的导热系数和热接触电阻。在微机电系统（MEMS）的帮助下，我们成功地制造出了具有阶梯形散热片的纳米探针。然而，对于较短长度的碳纳米管，重建t型纳米传感器非常困难，同时测量尚未成功。(3)除了测量单个CNTs的热导率外，还精确测量了不同厚度铂纳米膜的热导率和电导率。纳米膜的导热性和导电性的测量值都小于之前报道的体积值的一半。(4)详细研究了这些电导率与纳米膜厚度和晶粒尺寸的关系，并与已有的理论结果进行了比较。结果表明，电导率的降低主要是由于电子在晶界处的散射引起的。我们可以解释为什么Wiedemann-Frantz定律对纳米级厚度的金属薄膜不成立。(5)重复性非常好，本方法可以广泛应用于实际应用中。

(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.