Thermal Conductivity of Diamond Gems and CVD Diamond Films: Temperature and Isotopic Composition Dependence

Abstract

In order to investigate the reported high thermal conductivity (k) of isotopically pure ¹²C diamonds [1], we have measured k(T) of two synthetic gems of different isotopic compositions: (A) 1.1% ¹³C and (B) 0.04% ¹³C between 300 K and 550 K. The resultant k(T) data are shown in Fig. 1(a) (triangles) together with k(T) for natural Type IIa diamond from the literature [2]. Analysis of k(T) data was based on a comprehensive Klemens-Callaway model. The resultant phonon-impurity scattering contribution for the Type IIa data is within the uncertainty of Berman’s previous analysis [2]. The attenuation of k with increasing ¹³C concentration for our synthetic gem data (Fig. 1) can be attributed to the influence of the impurity term alone.