This work investigates the effects of concentration of organothiol molecules and temperature used during self-assembled monolayers (SAMs) formation on quality of the organothiol SAMs coating layer obtained in terms of wettability, corrosion inhibition efficiency and carbon to copper ratio. The organothiol SAMs were coated on copper substrates prepared by electro-polishing followed by oxygen plasma treatment for 15 s. Three types of organothiol SAMs including 1-octanethiol (OTT), 2-ethylhexanethiol (2-EHT) and 2-phenylethanethiol (2-PET) were investigated. Concentration of organothiol molecules ranging from 0.005 to 0.02 M in isopropanol and forming temperature ranging from -15 to 50°C were studied. It was found that all organothiol SAMs of 0.01 M provided the SAMs coating layer with the highest quality. The SAMs formed at 40°C with OTT and 2-EHT, and at 0°C with 2-PET were the most favorable condition with the highest water contact angle of 124.79o, 130.66o and 120.58o at corrosion inhibition efficiencies of 96.24%, 99.37% and 98.90%, respectively.

The synthesis of pure titania and carbon-titania nano-powders in a premixed atmospheric fuel-rich flame was studied. The variation of the flame C/O ratio allows to produce both pure titania and carbon-TiO2 nanoparticles. Raman Spectroscopy, X-ray Diffraction, Atomic Force Microscopy, Electrical Low Pressure Impactor and Scanning Electron Microscopy were used to characterize the synthesized nano-powders, in terms of crystallinity, phase content, size and morphology. Produced nano-powders with a dimension of 25-40 nm are composed by both rutile and anatase phases, with rutile being the predominant one. Reactive Oxygen Species analysis performed on the synthesized nano-powders showed that the inclusion of carbon in the nano-powders results in a reduced adverse health effect, in terms of ROS production.

In this work, we describe the synthesis of CdS nanocrystals in thin polymeric films by in-situ Grazing Incidence Diffraction (GID) and Grazing Incidence Small Angle Scattering (GISAXS). The 2D GISAXS patterns indicate how the precursor structure is altered as the temperature is varied from 25°C to 300°C. At 150°C, the CdS nanocrystals start to arrange themselves in a hexagonal lattice with a lattice parameter of 27 Å. The diffraction intensity from the hexagonal lattice reaches a maximum at 170°C and decreases steadily upon further heating above 220°C indicating loss of symmetry. Correspondingly, the GID scans at 170°C show strong crystalline peaks from cubic CdS nanocrystals that are about 2 nm size. The results indicate that a temperature of 170°C is sufficient to synthesize CdS nanocrystals without degradation of the polymer matrix (Topas) in thin films (about 30nm).

Nanosphere lithography (NSL) is a technique capable of creating large-area arrays of small objects with tailor-made shapes. Here we present an algorithm, which simulates the shape and morphology of nanoparticles produced via NSL in combination with physical vapor deposition from variable angles. The key idea is based on a ray-tracing technique. Mask clogging effects have a major influence on the shape of resulting nanoobjects and are therefore taken into account. In addition, we implemented a metaball concept for the precise description of thermally modified masks. The calculated results are compared exemplarily with atomic force microscopy (AFM) data of experimentally fabricated nanostructures.

Liquid-ion gated FET-type flexible graphene-based aptasensor was fabricated for Hg detection in real world samples. Single-layer graphene was grown and transferred onto a flexible substrate and integrated into the liquid-ion gated FET system via surface engineerging process. Field-induced responses to Hg2+ ions in real world samples were highly rapid, sensitive and selective, leading to the high-perfromance graphene aptasensor. The aptasensor also displayed excellent flexibility and mechanical durability.

We have experimentally investigated the anisotropy of Si-SiO2 interfacial energy by leveraging the mixed-phase solidification (MPS) method. By examining the microstructure evolution resulting from partial-melting-and-solidification cycles, and interpreting the changes in the surface-orientation distribution of the grains in terms of the thermodynamic model, we have identified the orientation-dependent hierarchical order of Si-SiO2 interfacial energies, σ{hkl}, as: σ{100} < σ{310} < σ{113} < σ{112} < σ{221} < σ{210}∼σ{331} < σ{111}, σ{110}.

Bromophenyl moieties were attached to the carbon-coated LiFePO4 (LiFePO4/C) surface by spontaneous reduction of in-situ generated 4-bromobenzene diazonium ions in organic media. The presence of the surface organic species on the grafted LiFePO4/C powders was confirmed by X-ray photoelectron spectroscopy. Thermogravimetric analyses revealed a low loading (lower than 1 wt. %) of grafted molecules. The electrochemical characterization of the LiFePO4/C cathodes showed that a low loading of bromophenyl groups at the LiFePO4/C surface can enhance the rate of Li+ extraction, presumably due to the decrease of the LiFePO4/C agglomerate size and an increase of the wettability of the electrode. On the other hand, poor performances were obtained using the grafted cathode material with the highest loading of bromophenyl moieties.

We report here on the chemical methodologies that are being settled in our labs for the insertion in diamond of foreign atoms and consequent creation of fluorescent defects. The inclusion of Si, Cr, Ge, able to produce color centers, is directly obtained during the process of diamond synthesis by means of a CVD technique. The deposition of the diamond films takes place on substrates of different nature, treated following procedures specifically settled to control the insertion of the different species. The photoluminescence emission from a series of diamond samples grown on different substrates (Si, Ge and Ti) has been investigated and is discussed with reference to the morphological/structural features of the diamond phase and to the experimental procedures adopted for substrate preparation.

Nowadays, there are limited referenced data on the hot deformation of twinning induced plasticity (TWIP) steels, particularly on the crystallographic preferred orientation (crystallographic texture). It is well know that texture is one of the most important factors affecting sheet metal forming performance. The aim of this research work is to determine the influence of microalloying elements on the microstructure and texture of high-Mn austenitic TWIP steels deformed under uniaxial hot-tensile conditions. For this purpose, one non-microalloyed and other single microalloyed with Ti, V and Mo TWIP steels were melted in an induction furnace and cast into metal and sand molds. Samples with average austenitic grain size between 400 and 2000 µm were deformed in the temperature range between 800 and 900 °C at a constant true strain rate of 10-3 s-1. The evolution of the microstructure and texture near to the fracture tip were characterized using electron back-scattering diffraction (EBSD) technique. The results show that the TWIP steels microalloyed with V and Mo and the non-microalloyed one, solidified in metal mold, exhibit dynamically recrystallized grains oriented in the [012] preferential direction, which was corroborated by local misorientation measurements, indicating low dislocation density. On the other hand, most TWIP steels solidified in sand molds do not show dynamically recrystallized grains, having the largest austenitic grains oriented in the [001]/[101] preferred directions. In general, weak textural Cube {001}<100> combined with <111> fiber, namely γ-fiber, spread from E {111}<110> to Y {111}<112> as major texture components were detected.

Alloyed nanorods and hybrid nanostructures composed of CuInS2 and ZnS were synthesized by heating-up and hot-injection procedures. The synthesis starts with the formation of copper sulfide seeds, which are subsequently converted to copper sulfide – copper indium zinc sulfide hybrid nanostructures, by incorporation of indium and zinc ions. The fraction of ZnS within the alloyed material could be controlled by the amount of the Zn precursor in the reaction solution. In reactions with higher zinc precursor concentrations, at longer reaction times L-shaped hybrid nanostructures are formed of CuInS2-ZnS alloy and ZnS. An additional injection of the Zn-precursor into the reaction solution results in the formation of U-shaped hybrid nanostructures.

Solid electrolyte interface (SEI) layer plays a key role in lithium-ion batteries’ degradation research. However, SEI layer microstructure prediction still needs further investigation, especially the lithium-ion diffusion in SEI layer considering its morphology evolution during the growth of SEI. Due to the unique advantage of avoiding explicitly tracking the interfaces with sharp composition gradients, a phase field model is developed to simulate the SEI formation and its morphology evolution that is regarded as a solidification process. Fick’s law and mass balance are applied to investigate lithium-ion concentration distribution and diffusion coefficients of different SEI layers (i.e., compact and porous SEI layers) predicted by the developed phase field model. The simulation results show lithium-ion diffusion coefficients between 298K and 318K are 1.34-1.87(10-16) m2/s and 1.73-2.18(10-12) m2/s for compact SEI and porous SEI layer, respectively. The developed model has great potential to be extended to three dimensional spaces for SEI layer spatial growth investigation and other interfaces with complex morphology evolution.

We have investigated two approaches for an alternative hole injection with a tunnel junction targeting deep UV-LEDs. One was an AlGaN-based tunnel junction. We fabricated the AlGaN-based tunnel junctions with various AlN mole fractions (0～0.2) grown on conventional blue-LEDs by MOVPE. A 7.5 nm heavily Mg-doped GaN/15 nm heavily Si-doped Al0.2Ga0.8N tunnel junction showed a large voltage drop, 5.31 V at 20 mA, under reverse bias. The other was a GaInN-based tunnel junction. We prepared Ga0.6In0.4N tunnel junctions with various thicknesses and Si doping levels grown on the blue LEDs by MOVPE. A 2 nm heavily Mg-doped Ga0.6In0.4N/3 nm heavily Si-doped GaN tunnel junction showed only 0.12 V drop at 20mA under reverse bias. Since an absorption of the thin GaInN tunnel junction was estimated to be less than 10 %, such a tunnel junction with small bandgap and thin layer thickness is a practical approach to obtain a low resistive and low absorptive hole injection in the deep UV-LEDs.

The transport properties, i.e. microstructural behavior and mechanisms related to water and ionic transport within the pore network of cement-based materials can be considered as an indicator for durability and to predict service life of concrete structures. Hence, the investigation of ionic transport is very important to asses ionic diffusion and ionic migration that potentially affect microstructural development of the bulk cement-based matrix. External electric fields are commonly accelerating ion (and water) migration. Numerical works on simulation of these phenomena have been reported, however, most of them consider only a constant ionic diffusion coefficient. This paper deals with the application of the Poisson-Nernst-Planck equations to simulate ionic transport in cement-based systems exposed to external electric potential by considering time dependent diffusion coefficient. The simulation involves solving the equation of mass conservation of individual ionic species coupled with electrostatic potential. Profiles of ionic concentrations and ionic distribution in cement-based systems are presented and discussed.

A synthetic cubic pyrochlore, Gd2Ti2O7 (Fd3̅m) irradiated with swift heavy ions is compared with a compositionally-related composition La2Ti2O7 (P2 1 ), which has a monoclinic, layered, perovskite-type structure. Irradiation experiments were performed at the GSI Helmholtz Center with 181Ta ions and 129Xe ions at specific energies of 11MeV/amu. At these energies the ions pass entirely through the sample thickness of ∼ 40 μm. Angle-dispersive synchrotron powder x-ray diffraction (XRD) measurements were completed and an increasing ion-induced amorphization with increasing ion fluence was for both phases. The ion track cross-sections for the radiation-induced crystalline-to-amorphous transformation, as determined from the evolution of the integrated peak intensities as a function of fluence, reveal that La2Ti2O7 (track diameter, d ∼ 7.2 nm with 181Ta and 5.1 nm with 129Xe) is more susceptible to amorphization than Gd2Ti2O7 (d ∼ 6.2 nm with 181Ta and 4.6 nm with 129Xe). The radiation response of the two titanate compounds can be understood in the context of their different structures and cation ionic radius ratios rA/rB, where the susceptibility of radiation of titanate pyrochlores is proportionate with this radius ratio. The higher electronic linear energy loss of the 181Ta ions as compared with 129Xe ions leads to a consistent increase of volume amorphized per ion in both materials, which manifests as a larger track diameter.