(Color online) Schematic illustration of the core-shell structure of a cylindrical nanowire. BOLS effect influences the outermost shell only, yet the core interior remains the bulk material properties. is the radius of the core and the shell has a thickness of three layers .
The dispersion curves of first five phonon branches for (a) torsional mode and (b) longitudinal mode with , 0.05, 0.10, and 0.15. The phonon frequency in general decreases as increases, in agreement with the findings given in Ref. 23. However, the phonon frequencies for the first branch increase compared to the original one for torsional mode and slightly varies for longitudinal mode with increasing . For the second branch, the phonon frequencies for longitudinal mode show a transition at .
Temperature dependence of the relative change of thermal conductivity for (a) torsional modes (b) and longitudinal modes for , 0.10, and 0.15.
Dependence of the relative change of thermal conductivity on the nanowire diameter at for torsional and longitudinal modes. The BOLS effects become more distinctive with the decrease of diameter and more pronounced for torsional mode.
Shell thickness, Lamé constants, velocities, and parameters related to different scattering mechanisms.
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