Evaporation Dynamics on a Lithium Niobate Surface

Manipulating the water evaporation dynamics is a prerequisite in various modern-day applications like DNA stretching, rapid disease diagnostics, and inkjet printing. One method to affect the evaporation dynamics of droplets is to externally apply electric fields. However, surfaces that bear an intrinsic surface charge have not yet been investigated with respect to their evaporation behavior. In this study, we investigate water droplet evaporation on lithium niobate (LN), a ferroelectric material with a very high spontaneous polarization of 0.7 C/m2 ${C/{m}<^>{2}}$ . Our results show that a droplet deposited on an LN surface evaporates in three stages: (i) constant contact radius (ii) mixed phase (iii) stick-slip, which is likely originating from the intrinsic surface charge. The influence of the polarization direction of the LN surface as well as the relative humidity of the environment on various evaporation characteristics were studied. The results suggest that the specific adsorption layers forming on charged surfaces, e. g. from the humidity of the surrounding air, play a key role in the evaporation process. Furthermore, compared to other materials with similar contact angles, LN demonstrated a significantly large evaporation rate. This property might also be attributed to the intrinsic surface charge and could be exploited in heat transfer applications. The image illustrates the evaporation dynamics of droplets on z-cut lithium niobate (LN). Evaporation has three stages: constant contact radius (CCR), mixed phase, and stick-slip. The LN ' s polarization direction influences contact angle and evaporation. Droplets on -z-cut surfaces have higher initial contact angles, resulting in longer durations for each phase compared to droplets on +z-cut surfaces. image