Determination of thermal conductivity using micro-Raman spectroscopy with a three-dimensional heating model

The thermal conductivity of isotropic graphite was investigated using Raman spectroscopy technique. In this method, the Raman laser acted simultaneously as an excitation source and a heating source. The dependences of the Raman peak position on temperature and laser power for the isotropic graphite were analyzed to establish Raman thermometry. Meanwhile, the local temperature rise induced by the laser irradiation was also theoretically described using a three-dimensional heating model, which can be related to the thermal conductivity. The laser absorptivity, the spot size, and the probing volume of Raman spectra were discussed, respectively. Besides, simulations of the localized temperature distribution were performed. On the basis of the Raman thermometry and the three-dimensional heating model, the thermal conductivity of 55 W/m K for the isotropic graphite was estimated, which was comparable with the value (60 W/m K) obtained by the laser flash technique.