The mechanical properties of systems consisting of copper coatings electrodeposited on both brass sheet (BS) and thick electrodeposited nickel coating (ED Ni) substrates have been investigated. The electrodeposition of copper coatings was performed with and without the ultrasound assistance. The ultrasound application decreases root mean square (RMS) roughness of deposited Cu coating on both applied substrates, as obtained from non-contact AFM measurement. The coating roughness is highly dependent on the substrate roughness, being the smallest for the Cu coatings deposited on ED Ni substrate with the ultrasound mixing. The hardness and adhesion properties were characterized using the Vickers microindentation test. Model of Korsunsky was applied to the experimental data for determination the film hardness and the model of Chen-Gao was used for the adhesion evaluation. The introduction of ultrasonic agitation caused the changes in the film microstructure, and consequently in the mechanical properties. The copper coatings on both substrates, have higher hardness when deposited from electrolyte with ultrasound agitation. Although the type of the substrate has the major influence on the adhesion strength, it can be said that Cu electrodeposition with ultrasonic mixing contributes to an increase in adhesion.
Nanomembranes are the most widespread building block of life, as they encompass cell and organelle walls. Their synthetic counterparts can be described as freestanding or free-floating structures thinner than 100 nm, down to monatomic/monomolecular thickness and with giant lateral aspect ratios. The structural confinement to quasi-2D sheets causes a multitude of unexpected and often counterintuitive properties. This has resulted in synthetic nanomembranes transiting from a mere scientific curiosity to a position where novel applications are emerging at an ever-accelerating pace. Among wide fields where their use has proven itself most fruitful are nano-optics and nanophotonics. However, the authors are unaware of a review covering the nanomembrane use in these important fields. Here, we present an attempt to survey the state of the art of nanomembranes in nanophotonics, including photonic crystals, plasmonics, metasurfaces, and nanoantennas, with an accent on some advancements that appeared within the last few years. Unlimited by the Nature toolbox, we can utilize a practically infinite number of available materials and methods and reach numerous properties not met in biological membranes. Thus, nanomembranes in nano-optics can be described as real metastructures, exceeding the known materials and opening pathways to a wide variety of novel functionalities.
Recently, biological nanostructures became an important source of inspiration for plasmonics, with many described implementations and proposed applications. Among them are brochosome-inspired plasmonic microstructures—roughly spherical core-shell particles with submicrometer diameters and with indented surfaces. Our intention was to start from the nanoplasmonic point of view and to systematically classify possible alternative forms of brochosome-inspired metal-containing particles producible by the state-of-the-art nanofabrication. A wealth of novel structures arises from this systematization of bioinspired metal-containing nanocomposites. Besides various surface nanoapertures, we consider structures closely related to them in electromagnetic sense like surface nano-protrusions, shell reliefs obtained by nano-sculpting, and various combinations of these. This approach helped us build a new design toolbox for brochosome-inspired structures. Additionally, we used the finite elements method to simulate the optical properties of simple brochosome-inspired structures. We encountered a plethora of advantageous optical traits, including enhanced absorption, antireflective properties, and metamaterial behavior (effective refractive index close to zero or negative). We conclude that the presented approach offers a wealth of traits useful for practical applications. The described research represents our attempt to outline a possible roadmap for further development of bioinspired nanoplasmonic particles and to offer a source of ideas and directions for future research.
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