Samuel Grandthyll

Universität des Saarlandes | UKS · Department of Experimental Physics

The epitaxial growth of graphene on transition metal surfaces by ex situ deposition of liquid precursors (LPD, liquid phase deposition) is compared to the standard method of chemical vapor deposition (CVD). The performance of LPD strongly depends on the particular transition metal surface. For Pt(111), Ir(111) and Rh(111), the formation of a graphe...

The epitaxial growth of graphene on the surface of an Ir/YSZ/Si(111) multilayer substrate via the deposition of a liquid carbon precursor (acetone) was investigated by x-ray photoelectron spectroscopy, x-ray photoelectron diffraction, low-energy electron diffraction (LEED), and Fermi surface mapping. It is shown that the onset of graphene formation...

Surface patterning in the micro- and nanometer-range by means of pulsed laser interference has repeatedly proven to be a versatile tool for surface functionalization. With these techniques, however, the surface is often changed not only in terms of morphology but also in terms of surface chemistry. In this study, we present an in-depth investigatio...

Post-cured epoxy layers (EP, approx. 100 nm and 1 µm) of three amine hydrogen – oxirane ratios are prepared in dried air on natively oxidised aluminium substrate. A less crosslinked interphase forms as the consequence of adhesive interactions. Even though the layers exhibit very good durability in moist-warm air for up to 100 d, two stages of chemi...

Microbial adhesion and the subsequent formation of resilient biofilms at surfaces are decisively influenced by substrate properties, such as the topography. To date, studies that quantitatively link surface topography and bacterial adhesion are scarce, as both are not straightforward to quantify. To fill this gap, surface morphometry combined with...

The etching behavior of polycrystalline synthetic hydroxyapatite samples has been evaluated to explore the protective impact of fluoride on a tooth-like model system. Etching rates before and after fluoridation with a NaF solution at pH 6 were determined by atomic force microscopy. Despite a very low F-concentration of ca. 0.2 at-% in the hydroxyap...

One of the treatments for recurrent or complicated osteomyelitis is by local antibiotherapy mediated by suitable bone grafts. β–Tricalcium Phosphate (β–TCP) bioceramic is a resorbable bone graft. Its microporosity allows for incorporation of drugs, but a too fast release is often obtained. Complex strategies have been explored to obtain controlled...

In the present study, nickel matrix composites reinforced with a fine distribution of nanodiamonds (6.5 vol%) as reinforcement phase are annealed in vacuum at different temperatures ranging from 750 °C to 1300 °C. This is carried out to evaluate the in-situ transformation of nanodiamonds to carbon onions within a previously densified composite. The...

The adhesive and mechanical properties of a modular fusion protein consisting of two different types of binding units linked together via a flexible resilin-like-polypeptide domain are quantified. The adhesive domains have been constructed from fungal cellulose-binding modules (CBMs) and an amphiphilic hydrophobin HFBI. This study is carried out by...

The occurrence of metallic film deposition without external power supply on the copper current collector of a zinc air battery half-cell containing zinc slurry is investigated. Therefore, test specimens of miscellaneous materials representing the current collector are immersed in a commercial available zinc slurry as well as an in self-prepared zin...

Fluoridation of enamel is believed to provide an effective tool to protect teeth from caries, but there is still little information on the timescale of fluoride uptake. In this study highly compressed pellets of hydroxyapatite are used as first-order model systems to approximate the mineral component of natural enamel for investigations on the time...

In late 2016, Rehman et al. reported on the synthesis of Yb doped CuFe2O4 nanoferrite adsorbents, i.e. CuYb0.5Fe1.5O4, and discussed this material´s adsorption performance in dependence on a large variety of parameters such as adsorbent dose, sonication time and concentrations of different pollutants, e.g. methyl orange, safranin, Cr3 + and Pb2 + [...

Seit dem ersten experimentellen Nachweis von Graphen im Jahre 2004 wurde dieses Material intensiv erforscht. Dabei wurden auch mögliche Anwendungs-Szenarien ausgelotet mit einer sehr großen Bandbreite von Reibungsminimierung bis hin zu elektronischen Bauteilen. Für diese Anwendungen sind zuverlässige und kostengünstige Syntheseverfahren notwendig....

Hydroxyapatite substrates are common biomaterials, yet samples of natural teeth do not meet the demands for well-defined, highly reproducible properties. Pellets of hydroxyapatite were produced via the Field Assisted Sintering Technology (FAST) as well as via pressureless sintering (PLS). The applied synthesis routes provide samples of very high de...

A large variety of tribological research studies dealt with the effect of laser induced surface textures and the respective parameters such as depth, feature diameter and area density on the tribological efficiency. However, only few studies have examined chemical and microstructural changes induced by the laser-patterning process which can have a...

Graphene formation on weakly interacting surfaces is of particular interest especially for transfer processes since the lack of strong covalent bonding may reduce the risk of inducing defects when separating the graphene layer from the metal support. The study by Grandthyll, Jacobs, and Müller (pp. 1695–1699) compares the performance of graphene fo...

In this work, we present a reduced graphene oxide-based impedimetric histamine biosensor. Histamine as a bioamine mediates immune-modulatory effects in acute inflammatory and allergic reactions. In a proof-of-principle approach, the low-cost sensor platform determines low concentrations of histamine in buffer solution with an impedimetric readout t...

The epitaxial growth of graphene on the Ag(001) surface via chemical vapor deposition (CVD) of propene and via liquid precursor deposition (LPD) by ex situ rinsing with acetone is investigated by X-ray photoelectron spectroscopy (XPS), low energy electron diffraction (LEED), and Fermi surface mapping (FSM). In case of LPD, the growth of graphene is...

Epitaxial graphene is expected to be the only way to obtain large-area sheets of this two-dimensional material for applications on an industrial scale. So far, there are different recipes for epitaxial growth of graphene, using either intrinsic carbon, such as the selective desorption of silicon from a SiC surface, or using extrinsic carbon, as via...

The mechanisms of action of fluoride have been discussed controversially for decades. The cavity-preventive effect is often traced back to effects on demineralization. However, an effect on bacterial adhesion was indicated by indirect macroscopic studies. To characterize adhesion on fluoridated samples on a single bacterial level, we used AFM force...

The wear resistance of a Rh(111) surface can be strongly increased by interstitial alloying with boron atoms via chemical vapour deposition of trimethylborate, B(OCH3)3 at moderate temperatures of about 800 K. The fragmentation of the precursor results in single boron atoms that are incorporated in the fcc lattice of the substrate, as displayed by...

In the very recent study by Hryniewicz et al. [1], the surface “of niobium after electrochemical electropolishing EP in sulfuricmethanesulfonic acid mixture” was investigated by SEM, EDX and photoelectron spectroscopy (XPS). The highlights of this study claim that the “main Nb surface stoichiometries (are) revealed by XPS”, leading to the central m...

Copper alloys (CuSn8, CuZn23Al3Co) have been micro-patterned with line-like geometries by Laser Interference Surface Structuring (LISS). In the presented study two high power pulsed laser beams are recombined to create unique, line-like intensity distributions with a chosen, constant periodicity of 10�m at varying laser fluencies. Anisotropic wetti...

In this work, the topographical and chemical effects of femtosecond laser irradiation on industrial 100Cr6 steel surfaces are analyzed. The irradiated areas present cavities with conical spikes at their center and an outer ring zone with periodical structures called sub-wavelength ripples. The number of pulses drastically influences the morphology...

Adhesion is a key issue for researchers of various fields, it is therefore of uppermost importance to understand the parameters that are involved. Commonly, only surface parameters are employed to determine the adhesive forces between materials. Yet, van der Waals forces act not only between atoms in the vicinity of the surface, but also between at...

The adsorption process of proteins to surfaces is governed by the mutual interactions among proteins, the solution, and the substrate. Interactions arising from the substrate are usually attributed to the uppermost atomic layer. This actual surface defines the surface chemistry and hence steric and electrostatic interactions. For a comprehensive un...

In order to investigate a way to diminish the impact of oxygen onto the critical cooling rate of Zr-based alloys, the bonding chemistry of the elements in Zr-Cu-Ni-Al-Nb-Si bulk metallic glasses with different oxygen contents is studied by x-ray photoelectron spectroscopy. Complementary undercooling experiments lead to continuous-cooling-transforma...

The epitaxial growth of graphene on the surface of an Ir/YSZ/Si(111) multilayer substrate via the deposition of a liquid carbon precursor (acetone) was investigated by x-ray photoelectron spectroscopy, x-ray photoelectron diffraction, low-energy electron diffraction (LEED), and Fermi surface mapping. It is shown that the onset of graphene formation...