Low temperature thermal conductivity of zinc oxide

The thermal conductivities of three large single crystals of zinc oxide have been measured, two from 3.5 to 300 K and one from 1.1 to 300 K. Two of the samples were hydrothermally grown and lithium doped, and one sample was vapor grown and undoped. The heat flow was parallel to the c-axis of one lithium-doped crystal and of the vapor grown crystal. These c-axis crystals had room temperature electrical resistivities of 0.4 and 5.0 Ωcm respectively. The heat flow was parallel to the a-axis in the other crystal, which had a room temperature electrical resistivity of approximately 106 Ωem as a result of the lithium doping. A very small anisotropy in the thermal conductivity was measured and is consistent with the results which are predicted from the Steigmeier and Kudman relation. The data were analyzed in terms of the Debye-Callaway model with a relaxation time that included boundary, dislocation, point defect, and Phonon–phonon scattering.