Mechanical and electrical properties of a nano-gap or how to play the nano-accordion

In-situ transmission electron microscopy (TEM) has become an important technique to study dynamic processes at highest spatial resolution and one branch is the investigation of phenomena related with electrical currents. Here, we present experimental results obtained from a peculiar in-situ TEM device, which was prepared with the aim to analyze the relationship between (thermo) electric properties and specific crystal orientations of a misfit layered compound. The formation of a nano-sized gap at a grain boundary facilitated a precisely controllable mechanical bending of the device by application of differential heating currents. The devices’ electrical properties were found to be substantially influenced by the gap, leading to a high intrinsic voltage. This voltage additionally depends on the vacuum environment and on the history of applied heating currents with internal field strengths of up to 37 kV m−1. These findings are largely attributed to the presence of adsorbed molecules within the gap region. The electrical in-situ TEM studies of this work illustrate that interior surfaces can strongly influence electrical properties even under high vacuum conditions.