Size-dependent thermal conductivity of zinc oxide nanobelts

The thermal conductivity of [011¯0]-oriented ZnO nanobelts 19–41Å in size is characterized over the temperature range of 500–1500K using the Green-Kubo approach. Values obtained are one order of magnitude lower than that for bulk ZnO single crystal. Surface scattering of phonons and the high surface-to-volume ratios of the nanobelts are primarily responsible for the significantly lower values and the size dependence observed. The conductivity is also found to decrease with temperature and this decrease is attributed to thermal softening of the material, three- and four-phonon processes, and optical phonon interactions.