Study of effect of water vapor and mechanical strain on thermal conductivity of zinc oxide using the ReaxFF reactive force field

Abstract

We present a study of the effect of strain on the thermal conductivity of the zinc oxide using ReaxFF reactive force field. Effect of water vapor on failure stress of zinc oxide has also been carried out. Force fields for zinc oxide and water have already been developed by Raymand et al. [1–3]. The thermal conductivity calculations were carried out using the Transient Non-Equilibrium Molecular Dynamics (T-NEMD) described by Bharathi and van Duin [4].For a zinc oxide nanowire, the effect of different values of mechanical strain – 0%, 2%, 6% and 10% (in the absence of water) on thermal conductivity is studied. No significant change in thermal conductivity is observed as the nanowire is stretched up to 6% strain (∼5W/mK) and is in good agreement with the results presented by Kulkarni and Zhou (Average value ∼5.5W/mK) [6]. The conductivity drops by 30% when the wire is stretched to 10% of its length. However, in contrast to the observations by Kulkarni et al. [7], no phase change is observed in our simulations.The effect of water vapor (system density – 1.04, 1.09, 1.18 and 1.24kg/m3) on the failure stress of zinc oxide nanowire is evaluated. The studies on effect water vapor on failure indicate that the failure stress drops from 14.25GPa in the absence of water vapor to 12.0GPa (−15.8%) for water vapor density of 1.24kg/m3. Significant hysteresis is observed with increasing water vapor density.As a practical application of T-NEMD, results from work on the sintering of zinc oxide nanoparticles in water vapor are reported.