ABSTRACT
Several x-ray measurements of the thermal expansion of diamond have been reported, including those of Krishnan, Thewlis and Davey, Novikova, and Sokhor and Vitol. Coefficients of linear thermal expansion α vs T have been measured by Thewlis and Davey for gem-quality and industrial diamonds. α for industrial diamonds shows a minimum of ∼255 K. In the Debye model, the specific heat of diamond is determined by the Debye temperature θD . A value of 1880 ± 10 K has been determined for θD by Victor based on the measurements of specific heat in the temperature range 300–1100 K. For low temperatures T < ∼θD /20, specific heat for the Debye model scales as T 3. The thermal conductivity κ of diamond at high temperatures scales as 1/T, which is due to the temperature dependence of the mean free path of phonons. At low temperatures, κ scales as T 3, which is due to the temperature dependence of the specific heat. The maximum value of κ is ∼5500 W/m.K at 125 K, which is 11 times higher than that of 500 W/m.K for copper.
