Influence of chemistry and topography on the wettability of copper.

To understand the complex interplay of topography and surface chemistry in wetting, fundamental studies investigating both parameters are needed. Due to the sensitivity of wetting to miniscule changes in one of the parameters it is imperative to precisely control the experimental approach. A profound understanding of their influence on wetting facilitates a tailored design of surfaces with unique functionality.

The Influence of Adventitious Carbon Groups on the Wetting of Copper: A Study on the Effect of Microstructure on the Static Contact Angle.

Tuning of the wetting behavior of metallic surfaces by chemical and topographical modification has become popular in recent years. Still, there is a lack in the understanding of fundamental relations between intrinsic properties of the material and its resulting water contact angle. It is widely accepted in the literature that transitions from a hydrophilic to increasingly hydrophobic behavior upon exposure to ambient conditions happen due to the adsorption of adventitious hydrocarbons.

An in-depth evaluation of sample and measurement induced influences on static contact angle measurements.

Static contact angle measurements are one of the most popular methods to analyze the wetting behavior of materials of any kind. Although this method is readily applicable without the need of sophisticated machinery, the results obtained for the very same material may vary strongly. The sensitivity of the measurement against environmental conditions, sample preparation and measurement conduction is a main factor for inconsistent results.

Janus bifunctional periodic mesoporous organosilica.

Synthesis of a Janus periodic mesoporous organosilica material (JPMO) is presented here. In this strategy, the surface of the hollow silica material was selectively functionalized with two different bridged organic-inorganic hybrid groups. It was found that the resulting bifunctional material is able to form a stable Pickering emulsion.

Influence of surface termination of ultrananocrystalline diamond films coated on titanium on response of human osteoblast cells: A proteome study.

Successful osseointegration, i.e. the fully functional connection of patient's bone and artificial implant depends on the response of the cells to the direct contact with the surface of the implant.

Achieving Ultra-Low Friction with Diamond/Metal Systems in Extreme Environments.

In the search for achieving ultra-low friction for applications in extreme environments, we evaluate the interfacial processes of diamond/tungsten sliding contacts using an on-line macro-tribometer and a micro-tribometer in an ultra-high vacuum. The coefficient of friction for the tests with the on-line tribometer remained considerably low for unlubricated sliding of tungsten, which correlated well with the relatively low wear rates and low roughness on the wear track throughout the sliding. Ex situ analysis was performed by means of XPS and SEM-FIB in order to better understand the underlying mechanisms of low friction and low-wear sliding.

Fabrication and Characterization of Single-Crystal Diamond Membranes for Quantum Photonics with Tunable Microcavities.

The development of quantum technologies is one of the big challenges in modern research. A crucial component for many applications is an efficient, coherent spin-photon interface, and coupling single-color centers in thin diamond membranes to a microcavity is a promising approach. To structure such micrometer thin single-crystal diamond (SCD) membranes with a good quality, it is important to minimize defects originating from polishing or etching procedures.

Absence of free carriers in silicon nanocrystals grown from phosphorus- and boron-doped silicon-rich oxide and oxynitride.

Phosphorus- and boron-doped silicon nanocrystals (Si NCs) embedded in silicon oxide matrix can be fabricated by plasma-enhanced chemical vapour deposition (PECVD). Conventionally, SiH and NO are used as precursor gasses, which inevitably leads to the incorporation of ≈10 atom % nitrogen, rendering the matrix a silicon oxynitride. Alternatively, SiH and O can be used, which allows for completely N-free silicon oxide.

Boron-Incorporating Silicon Nanocrystals Embedded in SiO: Absence of Free Carriers vs. B-Induced Defects.

Boron (B) doping of silicon nanocrystals requires the incorporation of a B-atom on a lattice site of the quantum dot and its ionization at room temperature. In case of successful B-doping the majority carriers (holes) should quench the photoluminescence of Si nanocrystals via non-radiative Auger recombination. In addition, the holes should allow for a non-transient electrical current.

Removing biofilms from stainless steel without changing surface properties relevant for bacterial attachment.

The influence of oxygen (and argon) plasma cleaning and a base-acid cleaning procedure on stainless steel surfaces was studied. The main aim was to clean stainless steel samples from Paracoccus seriniphilus biofilms without changing the surface properties which are relevant for bacterial attachment to allow reuse in a biofilm reactor. It is shown that oxygen plasma cleaning, which very successfully removes the same kind of biofilm from titanium surfaces, is not suitable for stainless steel.

Precise in situ etch depth control of multilayered III-V semiconductor samples with reflectance anisotropy spectroscopy (RAS) equipment.

Reflectance anisotropy spectroscopy (RAS) equipment is applied to monitor dry-etch processes (here specifically reactive ion etching (RIE)) of monocrystalline multilayered III-V semiconductors in situ. The related accuracy of etch depth control is better than 16 nm. Comparison with results of secondary ion mass spectrometry (SIMS) reveals a deviation of only about 4 nm in optimal cases.

Location and Electronic Nature of Phosphorus in the Si Nanocrystal--SiO2 System.

Up to now, no consensus exists about the electronic nature of phosphorus (P) as donor for SiO2-embedded silicon nanocrystals (SiNCs). Here, we report on hybrid density functional theory (h-DFT) calculations of P in the SiNC/SiO2 system matching our experimental findings. Relevant P configurations within SiNCs, at SiNC surfaces, within the sub-oxide interface shell and in the SiO2 matrix were evaluated.

Surface softening in metal-ceramic sliding contacts: an experimental and numerical investigation.

This study investigates the tribolayer properties at the interface of ceramic/metal (i.e., WC/W) sliding contacts using various experimental approaches and classical atomistic simulations.

Friction and wear mechanisms of tungsten-carbon systems: a comparison of dry and lubricated conditions.

The unfolding of a sheared mechanically mixed third-body (TB) in tungsten/tungsten carbide sliding systems is studied using a combination of experiments and simulations. Experimentally, the topographical evolution and the friction response, for both dry and lubricated sliding, are investigated using an online tribometer. Ex situ X-ray photoelectron spectroscopy, transmission electron microscopy, and cross-sectional focused ion beam analysis of the structural and chemical changes near the surfaces show that dry sliding of tungsten against tungsten carbide results in plastic deformation of the tungsten surface, leading to grain refinement, and the formation of a mechanically mixed layer on the WC counterface.

Chemical and structural characterisation of DGEBA-based epoxies by time of flight secondary ion mass spectrometry (ToF-SIMS) as a preliminary to polymer interphase characterisation.

Time-of-flight secondary ion mass spectrometry (ToF-SIMS) has become a powerful tool in the field of surface analysis since it provides information about the top few monolayers of a sample, i.e. on the chemical composition of the sample surface.