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Coalescence-induced droplet jumping on superhydrophobic surfaces have recently received significant attention owing to their potential in a variety of applications. Previous studies demonstrated that the self-jumping process is inherently inefficient, with an energy conversion efficiency η ≤ 6% and dimensionless jumping velocity V j* ≤ 0.23. To realize a quick removal of droplets, increasing effort has been devoted to breaking the jumping velocity limit and inducing droplets sweeping. In this work, we used superhydrophobic surfaces with an asymmetric V-groove to experimentally achieve an enhanced coalescence-induced jumping velocity V j* ≈ 0.61, i.e., more than 700% increase in energy conversion efficiency compared with droplets jumping on flat superhydrophobic surfaces, which is the highest efficiency reported thus far. Moreover, the enhanced jumping direction shows a deviation as high as 60° from the substrate normal. The induced in-plane motion is conducive to remove a considerable number of droplets along the sweeping path and significantly increase the speed of droplet removal. Numerical simulation indicated that the jumping enhancement is a joint effect resulting from the impact of the liquid bridge on the corner of the V-groove and the suppression of droplet expansion by the sidewall of the V-groove. The transient variation of the droplet velocity and the driving force of the coalescing droplets on a surface with and without the asymmetric V-groove were revealed and discussed. Furthermore, effects of groove angle, droplet pair positions, and size mismatches on the jumping velocity and direction have been studied. The novel mechanism of simultaneously increasing the coalescence-induced droplet jumping velocity and changing the jumping direction can be further studied to enhance the efficiency of various applications.

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The interface formation between Ba 0.6 Sr 0.4 TiO 3 and Al 2 O 3 has been studied using photoelectron spectroscopy with in situ sample preparation. A negligible valence band discontinuity, corresponding to a ϳ5.6 eV barrier for electron transport at the BST/ Al 2 O 3 interface is determined. Current-voltage measurements show that the leakage current can be significantly reduced by inserting the Al 2 O 3 barrier layer between barium strontium titanate ͑BST͒ and Pt electrode. Different charge injection behavior depending on Al 2 O 3 thickness is observed, which correspond well with the experimentally determined energy band diagrams. Direct tunneling from the metal electrode into the BST conduction band through the Al 2 O 3 barrier layer is observed.

We have measured the microwave resistance of highly conducting perovskite oxide SrMoO3 thin film coplanar waveguides. The epitaxial SrMoO3 thin films were grown by pulsed laser deposition and showed low mosaicity and smooth surfaces with a root mean square roughness below 0.3 nm. Layer-by-layer growth could be achieved for film thicknesses up to 400 nm as monitored by reflection high-energy electron diffraction and confirmed by X-ray diffraction. We obtained a constant microwave resistivity of 29 μΩ·cm between 0.1 and 20 GHz by refining the frequency dependence of the transmission coefficients. Our result shows that SrMoO3 is a viable candidate as a highly conducting electrode material for all-oxide microwave electronic devices.

When two or more droplets coalesce on a superhydrophobic surface, the merged droplet can jump spontaneously from the surface without requiring any external energy. This phenomenon is defined as coalescence-induced droplet jumping and has received significant attention due to its potential applications in a variety of self-cleaning, anti-icing, antifrosting, and condensation heat-transfer enhancement uses. This article reviews the research and applications of coalescence-induced droplet jumping behavior in recent years, including the influence of droplet parameters on coalescence-induced droplet jumping, such as the droplet size, number, and initial velocity, to name a few. The main structure types and influence mechanism of the superhydrophobic substrates for coalescence-induced droplet jumping are described, and the potential application areas of coalescence-induced droplet jumping are summarized and forecasted.

Hysteresis is induced in paraelectric (Ba,Sr)TiO3 (BST) thin‐film capacitors by inserting an Al2O3 barrier layer of a few nanometers in thickness between the BST layer and the electrode. The observed hysteresis is explained by ambipolar charge carrier injection through the Al2O3 layer and charge storage at the BST/Al2O3 interface. The magnitude of the hysteresis can be directly adjusted by manipulating the thickness ratio between BST and Al2O3. Taking into account the low loss of (Ba,Sr)TiO3 capacitors, the observed switching and retention characteristics are suitable for application as non‐volatile programmable high‐frequency devices, e.g., in radio‐frequency identification.