Thermal Conductivity of BeO Single Crystals

The thermal conductivities of three single crystals of BeO have been measured from 2 to 300 K. Phonons carry the heat at all temperatures. At 300 K the conductivity is 3.7 W/cm K, which is slightly less than that of copper. In the purest sample the maximum conductivity occurs at 45 K where it is 137 W/cm k, and at temperatures below 10 K the conductivity is limited by boundary scattering. The anisotropy in the conductivity of this hexagonal material is 20% or less.