P doped random C20 fullerite - model structure for fullerene-like CPx

Carbon-based amorphous and fullerene-like (FL) thin films have a great potential due to their mechanical resiliency. TEM investigation and interpretation of results from FL structures embedded in bulk phases is not straightforward. Here, a model is presented for description of the structure of FL-CP0.1 thin films and to describe all the rings in the electron diffraction pattern in a self-consistent way. The model structure consists of random close-packed and P-doped C20 clusters resembling a kind of amorphous fullerite (crystals of fullerene cages). The 10% P doping was implemented by creating C18P2 cages by replacing two C atoms by P in the C20 cage. The simulated electron scattering is in agreement with the experimental electron diffraction pattern and reproduces all the observed diffuse diffraction rings of FL-CP0.1 at 1.6, 2.6, and 5.9A. Simulation of HRTEM images confirmed the amorphous appearance of this nanostructured material

Plan-View Preparation of TEM Specimens from Thin Films Using Adhesive Tape

A simple plan-view sample preparation technique for transmission electron microscopy (TEM) specimens is proposed for thin films by tearing-off the film with adhesive tape. The demand for very thin samples is highest for nanostructured materials where the structure of 2–5 nm sized features (grains) needs to be resolved; therefore, overlapping of nanometer-sized features should be avoided. The method provides thin areas at the fracture edges of plan-view specimens with thickness in the range of the grain size in the film allowing for artifact free high-resolution TEM imaging. Nanostructured materials typically fracture between the grains providing areas with the thickness of the grain size. Besides the swiftness of the method, the samples are free of surface amorphization artifacts, which can occur in ion beam milling up to 1 nm depth even at low energy ion bombardment. The thin film tear-off technique is demonstrated on a CuMn alloy thin film with grain size of 2 nm

Influence of inert gases on the reactive high power pulsed magnetron sputtering process of carbon-nitride thin films

The influence of inert gases (Ne, Ar, Kr) on the sputter process of carbon and carbon-nitride (CNx) thin films was studied using reactive high power pulsed magnetron sputtering (HiPIMS). Thin solid films were synthesized in an industrial deposition chamber from a graphite target. The peak target current during HiPIMS processing was found to decrease with increasing inert gas mass. Time averaged and time resolved ion mass spectroscopy showed that the addition of nitrogen, as reactive gas, resulted in less energetic ion species for processes employing Ne, whereas the opposite was noticed when Ar or Kr were employed as inert gas. Processes in nonreactive ambient showed generally lower total ion fluxes for the three different inert gases. As soon as N2 was introduced into the process, the deposition rates for Ne and Ar-containing processes increased significantly. The reactive Kr-process, in contrast, showed slightly lower deposition rates than the nonreactive. The resulting thin films were characterized regarding their bonding and microstructure by x-ray photoelectron spectroscopy and transmission electron microscopy. Reactively deposited CNx thin films in Ar and Kr ambient exhibited an ordering toward a fullerene-like structure, whereas carbon and CNx films deposited in Ne atmosphere were found to be amorphous. This is attributed to an elevated amount of highly energetic particles observed during ion mass spectrometry and indicated by high peak target currents in Ne-containing processes. These results are discussed with respect to the current understanding of the structural evolution of a-C and CNx thin films. VC 2013 American Vacuum Society. [http://dx.doi.org/10.1116/1.4769725

Measuring of Fiber/Matrix Adhesion in Thermoplastic Polymer Composites: A Preliminary Study

The possibilities of the application of microbond test and cylinder tests for determining the interfacial shea r strength at the fiber - matrix interface in thermoplastic matrix polymer composites were investigated . Possibilities of test specimen preparation were also investigated. Finally the applicability of the method to make high precision measurement of interfac ial shear strength was evaluated

Development of Microcapsules

Melamine-formaldehyde (PMF) coated microcapsules were produced with liquid pentaerythritol-tetrakis (3-merkaptopropionate) (PETMP) and UV-sensitive indicator colored PETMP cores. Capsules with an average diameter of 43 μm formed due to the adjustments on magnetic stirring, compound ratios, acidity and reaction time. Reproducible recipe was found to produce colored PETMP filled capsules with yields of 1-10%. Optical microscopic investigations were conducted to follow the formation of the particles, and scanning electron-microscope (SEM) was used to verify that the capsules did not break up as an effect of the brittle failure of the epoxy matrix specimens. Improvement of the shell-matrix adhesion was attempted with silane compounds and investigated with X-ray photoelectron spectroscopy (XPS) and SEM.</jats:p