Transient phonon heat transport in quasi-1D nanostructures

The Debye model for heat capacity of crystals is used to study the phonon heat transfer properties of quasi-1D structures such as nanowires and nanorods. According to the results reported in previous literature, we schematize a nanowire by a stack of 40 cells, total length 400 nm, with zdirection for heat flux coincident with the axis of nanowire and initial temperature 300 K. Transient temperature (time step 2 ps) field is studied after that at t=0 the wall of the first cell is set at 500 K. The nanostructure dimensions considered in the plane perpendicular to the z-axis are 2-50 nm. Calculations are performed by Monte Carlo simulation for the phonon drift movements and scattering process. The main result is the following: the smaller sizes Lx, Ly, of the simulation cell in the plane perpendicular to the heat flux (x-, y-axis) does influences the rate of temperature transient response in the neighbouring of hot boundary (~50 nm) at short times (200 ps). Moreover, smaller Lx, Ly , yield to predicted longer times (~10 ns) for settling of linear temperature regime and to smaller heat conductivity within 10% at parity of heat flux.