Low-temperature specific heat, thermal conductivity, and ultrasonic velocity of glassy carbons

Abstract

We have measured the specific heat (0.1<T < 1 K) and thermal conductivity (0.07 <T<300 K) of two glassy carbons, one pyrolysed at 1000‡C, the other at 2500‡ C. The temperature dependence of ultrasonic velocity (0.2–300K) was also measured on the 2500‡C material. The above properties are remarkably similar to those of amorphous materials, yet it appears that these features arise from origins other than the localized excitations responsible for the low-temperature behavior of amorphous materials.