Surface effects on the electromechanical coupling and bending behaviours of piezoelectric nanowires

In this work, surface effects, including surface elasticity, residual surface stress and surface piezoelectricity, are considered to study the electromechanical coupling (EMC) behaviour of piezoelectric nanowires (NWs) with the Euler-Bernoulli beam theory. Using the surface-layer-based model, explicit formula for EMC coefficient is derived. It is clearly observed that this coefficient is size-dependent and can be strongly enhanced when the geometric dimensions of NWs scale down. The static bending of a cantilever piezoelectric NW is also studied. The surface effects are found to significantly influence the stiffness and electric field distribution in the NW. The results indicate that surface effects play a significant role in the EMC and bending behaviours of piezoelectric nanobeam. This work is very helpful for understanding the size-dependent properties of nanostructured piezoelectric materials and improving the performance of the piezoelectric nanobeam-based devices in energy harvesting.