Quartz crystal microbalance studies of disorder-induced lubrication

We report here a quartz crystal microbalance (QCM) study of the friction associated with sliding of solid and liquid krypton films on ordered and disordered gold substrates, where lower friction is observed for the disordered substrates. The gold substrates on which the measurements were performed were prepared by depositing gold films onto polished quartz substrates held at 80 and 300 K, the 80 K samples being the more disordered of the two. The fact that lower friction levels were observed for more disordered systems may, potentially, be explained by the inhibition of phonon excitations in these systems.