Experimental and Theoretical Analysis of the High Temperature Thermal Conductivity of Monocrystalline SiC

Abstract

The thermal properties of monocrystalline 6H-SiC have been studied within the temperature range 300-2300 K. The thermal diffusivity a was measured with the laserflash method up to 2300 K. The specific heat capacity c{sub p} was determined from room temperature up to 1650 K. From thermal diffusivity data, the c{sub p} data fitted by the Debye-model and the density {rho} taken partly from measurements and partly from literature the thermal conductivity {kappa} was evaluated from {kappa} = a(T) x {rho}(T) x c{sub p}(T) to give {kappa}/[Wm{sup -1}K{sup -1}]{approx_equal}451700 x (T/[K]){sup -1.29}. The theoretical analysis of the given high temperature thermal conductivity data and of low temperature data taken from literature shows, that the phonon contribution is dominant within the whole temperature range (8-2300 K). Within a Callaway analysis a Grueneisen-parameter {gamma} = 1.5 was found. Unipolar and bipolar electronic contributions to the thermal conductivity seem to be negligible. At temperatures {>=}1500 K additionally heat transport by radiation becomes relevant. (orig.) 15 refs.