Thermal diffusivity measurement of chemical-vapor-deposited diamond by an AC calorimetric method

An ac calorimetric method has been extensively applied to the thermal diffusivity measurement of a variety, of materials from polymer to diamond. In a sample with high thermal diffusivity, the reflection of ac temperature waves at the edge of the sample affects the thermal diffusivity measurement. In addition, in a short sample, it becomes very significant. In this paper, we propose a new method to derive the thermal diffusivity in such a sample from the decay and the phase shift of ac temperature waves. We applied the present method to the thermal diffusivity measurement of chemical-vapor-deposited (CVD) diamond plates. As a result, it was found that the obtained thermal diffusivity for the diamond sample with finite length agrees with that of the plate-like sample with infinite length.