SYNTHESIS AND ELECTRICAL PROPERTIES OF THIN FILMS OF FULLERITES ON THE VARIOUS SUBSTRATES

In the process of intercalation, C60 samples in the form of polycrystalline films prepared on various substrates are used. To obtain a homogeneous doping we test two geometrical set-ups of our apparatus, horizontal and vertical. In the present work we focus on the study of transport properties of the samples. We demonstrate the temperature dependence of the conductivity of doped C60 films during the doping process. The time evolutions of the sample resistivity after its exposure to the atmosphere are studied. The structural properties of the samples are examined by X-ray diffraction technique in Bragg-Brentano geometry and Raman Spectroscopy. Scanning Electron Microscopy is used to compare the surface morphology of the undoped and doped C60 films

Transformer fault detection based on Raman analysis of the transformer oil (A case study)

We are grateful to the scientific grant agency VEGA of the Ministry of Education, Science, Research and Sport of the Slovak Republic for financial support of project No. 1/0532/19 and to the Slovak Research and Development Agency, contract No.APVV-17-0169.The paper reports on an experiment in the academic laboratory that aimed to detect a transformer fault by Raman spectroscopy of the transformer oil. Indicators of oil degradation (eg gases, sludge, cellulose) could not be detected. Combustion indicators (soot – graphitic particles, graphene particles, amorphous carbon) in the transformer oil were reliably detected by Raman measurements. The transformer was disassembled at the factory. It was shown that the magnetic core and electrical circuit of the transformer were irreversibly damaged and the contamination of the active parts of the transformer and the oil was massive. Two interturn short circuits were detected. It was confirmed that in the place of the coil shorts, where an electric arc burned, melting occurred of the winding conductors and of a part of the transformer core. Raman spectroscopy proved to be a useful method for rapid diagnostics of the events in a hermetically sealed transformer vessel

Detection of pollutants in the grease of a bearing by EDS and SEM: A case study

VEGA of the Ministry of Education, Science, Research and Sport of the Slovak Republic for financial support of project No. 1/0532/19, and to the SlovakResearch and Development Agency, contract No. APVV-17-0169.The most common cause of mechanical failure of brushed electric motors is the damage to the commutator and brushes but in harsh environments also mechanical damage to the bearings occurs. One of the main grounds of bearing damage is an unsuitable lubricant, various microparticles entering the lubricant on grinding poor quality bearing parts or inclusions related to the mechanical wear of the commutator. We examined the foreign substances or particles in the grease (petroleum jelly) of the bearing by Energy Dispersive X-ray Spectroscopy (EDS) of the components of a used commutator and of a new one. After disassembling the bearing, we analysed the cage, balls, grease and inner ring of the bearing. The obtained results indicate that the undesirable properties of the studied bearing are related to defects in the metallic components of the bearing and to the content of impurities in the lubricant

Elimination of the Leakage Inductance of the Primary Winding of an Impulse Transformer for a Contact-less Temperature Gauge

We continue in reconstruction of the temperature meter with optical transmission of temperature reading in the HF CVD reactor. The parasitic inductance causes degradation of the transformer. The issue is solved by including a non-dissipative snubber that recuperates the energy from the parasitic inductance back to the power supply and allows faster demagnetization, thereby improving the transfer of energy through the transformer to its secondary winding

Hybridization of natural inorganic materials (natural minerals) by carbon nanotubes

In this work we briefly summarized results of extensive experiments focused on hybridization natural inorganic substrates by carbon nanotubes (CNTs). The kernel of the experiments is catalytic synthesis of CNTs on/into natural inorganic substrates involving two technological processes. The first one is incorporation of catalytically active metals into the structure of the substrates while the second one is in-situ synthesis of CNTs in a HF CVD reactor. The main objective of the experiments is to contribute to understanding the mechanism of the rise of new hybrid materials. Selection of the natural inorganic substances includes a group of minerals with similar chemical compositions but with markedly different morphologies as well as materials containing iron - colloid scraps after raw mineral mining. The main methods of characterizing the hybrids are Raman spectroscopy along with scanning and transmission electron microscopies

Raman spectroscopy used to assess the temperature and mechanical stress in thin films of microelectronic structures

We are grateful to the scientific grant agency of the Ministry of Education, Science, Research and Sport of the Slovak Republic for financial support of project VEGA No. 1/0947/16.In this experimental work we examined the temperature and mechanical stress in the thin films of microelectronic structures based on GaN and AlN by Raman spectroscopy. The rise in temperature in the Raman spectrum is shown by shifting the Raman bands toward lower wavenumbers. Similarly like with changes of temperature, the changes of the positions of Raman bands may indicate the changes of mechanical stress in the structure. It was confirmed experimentally that in the case of tensile stress the Raman bands are shifted towards lower wavenumbers, and under compressive stress to higher wavenumbers

Effect of Surfaces of FeNbCuBSiP Ribbons

Boron was partially substituted by phosphorus (3 at.%) in two Si-poor Fe-Nb-Cu-B-Si Finemets. Mostly non-significant changes were observed after vacuum annealing at 500°C, whereas equivalent Ar annealing resulted in significantly better soft-magnetic properties, which suffer from compressive surfaces stress. Possibly by hampering surface crystallization, the substitution eased the surfaces stress and reduced undesired off-axis anisotrophy at the cost of limiting the useful annealing temperature

Raman spectroscopy of silicon with nanostructured surface

We compared the morphology and Raman response of nanoscale shaped surfaces of Si substrates versus monocrystalline Si. Samples were structured by reactive ion etching, and four of them were covered by a RuO2-IrO2 layer. Raman bands, centred at approx. 520 cm–1, belonging to samples processed by etching the Si surface have intensities higher by approximately one order of magnitude than those of reference non-etched samples. For nanostructured samples, the rise in the Raman signal was 12–14 ×, which is in agreement with the model of the electric field at the tips of Si due to their geometry. This phenomenon is related to the high absorption of excitation radiation. Nanostructured surfaces of samples containing a layer of RuO2-IrO2 give rise to the phenomenon of surface enhancement of the Raman response most likely due to the charge transfer at the interface between silicon and conductive oxides. The nanostructured surface of Si without a metal layer behaves as a SERS substrate and detects the analytes at a low concentration.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Photovoltaic Materials and DevicesElectrical Sustainable Energ