Synthesis and Characterization of Multilayered CrAlN/AlO Tandem Coating Using HiPIMS for Solar Selective Applications at High Temperature.

The effect of applying a negative bias during deposition of a previously designed multilayer solar selective absorber coating was studied on two types of substrates (316L stainless steel and Inconel 625). The solar selective coating is composed of different chromium aluminum nitride layers deposited using a combination of radiofrequency (RF), direct current (DC), and high-power impulse magnetron sputtering (HiPIMS) technologies. The chemical composition is varied to generate an infrared reflective/absorber layer (with low Al addition and N vacancies) and two CrAlN intermediate layers with medium and high aluminum content (Al/Cr = 0.

High-Quality /O-Terminated Diamond Interface: Band-Gap, Band-Offset and Interfacial Chemistry.

Silicon oxide atomic layer deposition synthesis development over the last few years has open the route to its use as a dielectric within diamond electronics. Its great band-gap makes it a promising material for the fabrication of diamond-metal-oxide field effects transistor gates. Having a sufficiently high barrier both for holes and electrons is mandatory to work in accumulation and inversion regimes without leakage currents, and no other oxide can fulfil this requisite due to the wide diamond band-gap.

Titania Enhanced Photocatalysis and Dye Giant Absorption in Nanoporous 1D Bragg Microcavities.

Light trapping effects are known to boost the photocatalytic degradation of organic molecules in 3D photonic structures of anatase titania (a-TiO) with an inverse opal configuration. In the present work, we show that photocatalytic activity can also be enhanced in a-TiO thin films if they are incorporated within a nanoporous 1D optical resonant microcavity. We have designed and manufactured multilayer systems that, presenting a high open porosity to enable a straightforward diffusion of photodegradable molecules, provide light confinement effects at wavelengths around the absorption edge of photoactive a-TiO.

Patterning and control of the nanostructure in plasma thin films with acoustic waves: mechanical vs. electrical polarization effects.

Nanostructuration and 2D patterning of thin films are common strategies to fabricate biomimetic surfaces and components for microfluidic, microelectronic or photonic applications. This work presents the fundamentals of a surface nanotechnology procedure for laterally tailoring the nanostructure and crystalline structure of thin films that are plasma deposited onto acoustically excited piezoelectric substrates. Using magnetron sputtering as plasma technique and TiO as case example, it is demonstrated that the deposited films depict a sub-millimetre 2D pattern that, characterized by large lateral differences in nanostructure, density (up to 50%), thickness, and physical properties between porous and dense zones, reproduces the wave features distribution of the generated acoustic waves (AW).

Pd-C Catalytic Thin Films Prepared by Magnetron Sputtering for the Decomposition of Formic Acid.

Formic acid is an advantageous liquid organic hydrogen carrier. It is relatively nontoxic and can be synthesized by the reaction of CO with sustainable hydrogen or by biomass decomposition. As an alternative to more widely studied powdery catalysts, supported Pd-C catalytic thin films with controlled nanostructure and compositions were newly prepared in this work by magnetron sputtering on structured supports and tested for the formic acid decomposition reaction.

Porous Graphene-like Carbon from Fast Catalytic Decomposition of Biomass for Energy Storage Applications.

A novel carbon material made of porous graphene-like nanosheets was synthesized from biomass resources by a simple catalytic graphitization process using nickel as a catalyst for applications in electrodes for energy storage devices. A recycled fiberboard precursor was impregnated with saturated nickel nitrate followed by high-temperature pyrolysis. The highly exothermic combustion of in situ formed nitrocellulose produces the expansion of the cellulose fibers and the reorganization of the carbon structure into a three-dimensional (3D) porous assembly of thin carbon nanosheets.

Hydrophobicity, Freezing Delay, and Morphology of Laser-Treated Aluminum Surfaces.

Until recently, superhydrophobicity was considered as a hint to predict surface icephobicity, an association of concepts that is by no means universal and that has been proven to depend on different experimental factors and material properties, including the actual morphology and chemical state of surfaces. This work presents a systematic study of the wetting and freezing properties of aluminum Al6061, a common material widely used in aviation, after being subjected to nanosecond pulsed IR laser treatments to modify its surface roughness and morphology. All treated samples, independent of their surface finishing state, presented initially an unstable hydrophilic wetting behavior that naturally evolved with time to reach hydrophobicity or even superhydrophobicity.

Author Correction: Strong activation effect on a Ru-Co-C thin film catalyst for the hydrolysis of sodium borohydride.

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper.

Strong activation effect on a ru-co-c thin film catalyst for the hydrolysis of sodium borohydride.

In this work, we prepared a series of Ni foam supported Ru-Co, Ru-Co-B and Ru-Co-C catalysts in the form of columnar thin films by magnetron sputtering for the hydrolysis of sodium borohydride. We studied the activity and durability upon cycling. We found a strong activation effect for the Ru-Co-C sample which was the highest ever reported.

Combined TGA-MS kinetic analysis of multistep processes. Thermal decomposition and ceramification of polysilazane and polysiloxane preceramic polymers.

The polymer-to-ceramic transformation kinetics of two widely employed ceramic precursors, 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane (TTCS) and polyureamethylvinylsilazane (CERASET), have been investigated using coupled thermogravimetry and mass spectrometry (TG-MS), Raman, XRD and FTIR. The thermally induced decomposition of the pre-ceramic polymer is the critical step in the synthesis of polymer derived ceramics (PDCs) and accurate kinetic modeling is key to attaining a complete understanding of the underlying process and to attempt any behavior predictions. However, obtaining a precise kinetic description of processes of such complexity, consisting of several largely overlapping physico-chemical processes comprising the cleavage of the starting polymeric network and the release of organic moieties, is extremely difficult.

The interaction between hybrid organic-inorganic halide perovskite and selective contacts in perovskite solar cells: an infrared spectroscopy study.

The interaction of hybrid organic-inorganic halide perovskite and selective contacts is crucial to get efficient, stable and hysteresis-free perovskite-based solar cells. In this report, we analyze the vibrational properties of methylammonium lead halide perovskites deposited on different substrates by infrared absorption (IR) measurements (4000-500 cm(-1)). The materials employed as substrates are not only characterized by different chemical natures (TiO2, ZnO and Al2O3), but also by different morphologies.

Optofluidic Modulation of Self-Associated Nanostructural Units Forming Planar Bragg Microcavities.

Bragg microcavities (BMs) formed by the successive stacking of nanocolumnar porous SiO2 and TiO2 layers with slanted, zigzag, chiral, and vertical configurations are prepared by physical vapor deposition at oblique angles while azimuthally varying the substrate orientation during the multilayer growth. The slanted and zigzag BMs act as wavelength-selective optical retarders when they are illuminated with linearly polarized light, while no polarization dependence is observed for the chiral and vertical cavities. This distinct optical behavior is attributed to a self-nanostructuration mechanism involving a fence-bundling association of nanocolumns as observed by focused ion beam scanning electron microscopy in the slanted and zigzag microcavities.

Fabrication of Optical Multilayer Devices from Porous Silicon Coatings with Closed Porosity by Magnetron Sputtering.

The fabrication of single-material photonic-multilayer devices is explored using a new methodology to produce porous silicon layers by magnetron sputtering. Our bottom-up methodology produces highly stable amorphous porous silicon films with a controlled refractive index using magnetron sputtering and incorporating a large amount of deposition gas inside the closed pores. The influence of the substrate bias on the formation of the closed porosity was explored here for the first time when He was used as the deposition gas.

STEM-in-SEM high resolution imaging of gold nanoparticles and bivalve tissues in bioaccumulation experiments.

The methodology termed scanning transmission electron microscopy in scanning electron microscopy (STEM-in-SEM) has been used in this work to study the uptake of citrate stabilized gold nanoparticles (AuNPs) (average particle sizes of 23.5 ± 4.0 nm) into tissue samples upon in vitro exposure of the dissected gills of the Ruditapes philippinarum marine bivalve to the nanoparticle suspensions.

Osteoblasts Interaction with PLGA Membranes Functionalized with Titanium Film Nanolayer by PECVD. Assessment of Surface Influence on Cell Adhesion during Initial Cell to Material Interaction.

New biomaterials for Guided Bone Regeneration (GBR), both resorbable and non-resorbable, are being developed to stimulate bone tissue formation. Thus, the study of cell behavior towards material surface properties turns a prerequisite to assess both biocompatibility and bioactivity of any material intended to be used for clinical purposes. For this purpose, we have developed studies on normal human osteoblasts (HOB) HOB osteoblasts grown on a resorbable Poly (lactide-co-glycolide) (PLGA) membrane foil functionalized by a very thin film (around 15 nm) of TiO (, TiO₂/PLGA membranes), designed to be used as barrier membrane.

A nanoscale characterization with electron microscopy of multilayered CrAlYN coatings: a singular functional nanostructure.

A combination of transmission electron microscopy techniques and spatially resolved microanalysis is used to investigate the nanostructure, constituting phases, and chemical elemental distribution in CrAlYN multilayered coatings. The location of the metallic elements and their chemical state are needed to understand their functional properties. Samples were prepared with variable Al (4-12 at%) and Y (2-5 at%) contents by direct current reactive magnetron sputtering on silicon substrates using metallic targets and Ar/N2 mixtures under different deposition parameters (power applied to the target and rotation speed of the sample holder).

Behaviour of Au-citrate nanoparticles in seawater and accumulation in bivalves at environmentally relevant concentrations.

The degree of aggregation and/or coalescence of Au-citrate nanoparticles (AuNPs, mean size 21.5 ± 2.9 nm), after delivery in simulated seawater, are shown to be concentration-dependent.

Roughness assessment and wetting behavior of fluorocarbon surfaces.

The wetting behavior of fluorocarbon materials has been studied with the aim of assessing the influence of the surface chemical composition and surface roughness on the water advancing and receding contact angles. Diamond like carbon and two fluorocarbon materials with different fluorine content have been prepared by plasma enhanced chemical vapor deposition and characterized by X-ray photoemission, Raman and FT-IR spectroscopies. Very rough surfaces have been obtained by deposition of thin films of these materials on polymer substrates previously subjected to plasma etching to increase their roughness.

Wetting properties of polycrystalline TiO2 surfaces: a scaling approach to the roughness factors.

This work presents a thorough study on the wettability of polycrystalline anatase TiO(2) thin films prepared at 250 °C in a microwave plasma enhanced chemical vapor deposition (MW-PECVD) reactor with Ar/O(2) plasmas. Anatase polycrystalline thin films with different microstructures, textures, and surface roughness were obtained as a function of their thickness. The water contact angle of the samples was analyzed within the assumptions of the Wenzel, Cassie, and Miwa models to ascertain the effect of roughness and other surface heterogeneities on their characteristic parameters.

Preillumination of TiO2 and Ta2O5 photoactive thin films as a tool to tailor the synthesis of composite materials.

Illumination of TiO 2 thin films with UV light is known to induce the transformation of the surface of this material from partially hydrophobic into fully hydrophilic. The present work shows that this transformation is accompanied by other effects that may be used to control the synthesis of composite materials. For this purpose, TiO 2 and Ta 2O 5 transparent thin films with a columnar structure and open pores were prepared by electron evaporation at glancing angles.

Supported Ag-TiO(2) core-shell nanofibres formed at low temperature by plasma deposition.

Ag-TiO(2) nanofibres (about three microm long and 30-150 nm thick) formed by a single-crystalline silver wire (20-30 nm thick) and an external layer of amorphous TiO(2) of variable thickness are prepared at 403 K by oxygen plasma activation of a silver substrate followed by plasma deposition of TiO(2). Thicker fibres of anatase crystallites surrounding the silver wire were prepared when plasma deposition was carried out at 523 K. The fibres have been analysed by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and x-ray photoemission spectroscopy (XPS).