Thermal boundary conductance in amorphous superlattices – Congrats Ash!

We have shown that the thermal boundary conductance across solid interfaces can change based on whether the materials comprising the interfaces are amorphous or crystalline.  Via a series of MD simulations, we show that mode distribution in amorphous materials can lead to an increase in thermal boundary conductance as compared to their crystalline counterparts.  This work, in which Ash Giri was the first author, was recently published in Journal of Applied Physics (Journal of Applied Physics 118, 165303 (2015)), and was in collaboration with Dr. John Duda from Seagate Technology.

Abstract

We report on the thermal conductivities of amorphous Stillinger-Weber and Lennard-Jones superlattices as determined by non-equilibrium molecular dynamics simulations. Thermal conductivities decrease with increasing interface density, demonstrating that interfaces contribute a non-negligible thermal resistance. Interestingly, Kapitza resistances at interfaces between amorphous materials are lower than those at interfaces between the corresponding crystalline materials. We find that Kapitza resistances within the Stillinger-Weber based Si/Ge amorphous superlattices are not a function of interface density, counter to what has been observed in crystalline superlattices. Furthermore, the widely used thermal circuit model is able to correctly predict the interfacial resistance within the Stillinger-Weber based amorphous superlattices. However, we show that the applicability of this widely used thermal circuit model is invalid for Lennard-Jones based amorphous superlattices, suggesting that the assumptions made in the model do not hold for these systems.