Nitridation of different materials using ion implantation is of considerable interest for many applications. As electronic components, oxynitride (SiOxNy) layers exhibit beneficial properties such as precise compositional variability, refractive index tunability, oxidation resistance, and low mechanical stress. In the present study we investigate nanoscale SiOxNy synthesized using ion implantation methods. To introduce N+ ions into a shallow Si subsurface region, both conventional ion beam implantation and plasma immersion ion implantation with subsequent high-temperature treatment in dry O2 are used. The optical and morphological properties and chemical bonding of formed SiOxNy layers were studied by applying spectroscopic ellipsometry in the range of VIS-Near IR (SE) and IR (IR-SE), Raman spectroscopy and Atomic Force Microscopy (AFM). Monte Carlo modeling of implant profiles contributed to understanding physical and chemical processes and predicted different influences of the incorporated N+ ions on the oxidation mechanism, confirmed by the thickness dependence of SiOxNy/Si layers obtained from the SE data analysis. IR-SE spectral analysis established the formation of Si-O, Si-N, Si-N-O and Si-Si chemical bonds in the grown layers. The occurrence of amorphization of the Si crystal lattice due to incorporation of high-energy N+ ions into the Si lattice is confirmed by the Raman and ellipsometry results. The free Si atoms can congregate, forming nanocrystalline clusters. AFM imaging revealed that both implantation methods left the surface of the resulting SiOxNy layers considerably smooth with similar roughness parameter values. The results of the studies imply that the technological approaches used allow the production of high-quality nanoscale silicon oxynitride films with appropriate tunable composition and properties for possible application in advanced electronic devices for nanoelectronics, optoelectronics and sensor applications.

This work focuses on the study of tribo-mechanical and microstructural properties of TiCN/ZrCN multilayer coatings with a modulation period of 12 nm, obtained by a conventional cathodic arc technique. The coatings were deposited at a temperature of 320 °C using nitrogen and methane reactive gases (N2/CH4) mixture in three different proportions. Surface morphology, composition, hardness, adhesion, friction and wear behavior were studied using atomic force microscopy, scanning electron microscopy with energy dispersive spectroscopy, X-ray diffraction, Raman spectroscopy, nanoindentation, and scratch and wear tests. The analysis of the coating composition revealed a strict dependence of the carbon content on the CH4 flow rate. It was found that the coatings with a carbon content of 14.6 at.% and 15.9 at.% consist of crystalline TiZr (C,N) with the presence of amorphous carbon. All the studied TiCN/ZrCN coatings showed improved tribo-mechanical properties compared to TiN/ZrN multilayers obtained under the same deposition conditions. The highest hardness of 40 GPa was obtained for the coating deposited at a N2/CH4 flow rate of 370/100 sccm. The lowest wear rate of 3.16 × 10-6 mm3/N·m under dry sliding conditions was observed in the multilayer coatings deposited at the N2/CH4 flow rates of 330/140 sccm.

Since the early days of silicon manufacturing, hydrogen gas treatment has been used to control the defect concentrations. Its beneficial effect can be enhanced using hydrogen plasma as a source of active atomic hydrogen. Hydrogen plasma modification of c-Si surface can be challenging because the plasma can induce precursors of defect centers that can persist at the interface and/or grown oxide after subsequent thermal oxidation. In the present study, we investigate nanoscale silicon dioxides with thicknesses in the range of 6–22 nm grown at low temperature (850 °C) in dry oxygen on radio frequency (RF) hydrogen plasma-treated silicon surface. The properties of these oxides are compared to oxides grown following standard Radio Corporation of America (RCA) Si technology. Electroreflectance measurements reveal better interface quality with enhanced electron mobility and lowered oxidation-induced stress levels when the oxides are grown on H-plasma modified c-Si substrates. These results are in good accordance with the reduced defect concentration established from the analysis of the current–voltage (I-V) and multifrequency capacitance–voltage (C-V) characteristics of metal-oxide-semiconductor (MOS) capacitors incorporating the Si-SiO2 structures. The study proves the potential of hydrogen plasma treatment of Si prior to oxidation for various Si-based applications.

It has recently been shown both theoretically and experimentally that a significant modification of the aC:H films is possible using UV irradiation even with a very low irradiation fluence. Some initial results on the modification of aC:H films with thickness of about 40 nm with UV laser irradiation are presented here. The fourth harmonic (λ = 266 nm) of a Nd:YAG laser system (the fundamental wavelength λ = 1064 nm) was used in our experiments. The modified areas of the aC:H films were characterized by optical microscopy, Raman spectroscopy as well as by atomic force microscopy (AFM). A significant modification of aC:H films under certain conditions (laser irradiation fluence and modification modes) to multi-layer graphene accompanied by ablation of a part of the film was established. It was also found that similar aC:H films deposited on 330 nm SiO 2 /Si substrates did not undergo significant modification under these conditions.

In this paper, the electrical transport in free-standing graphene and N-graphene sheets fabricated by a microwave plasma-based method is addressed. Temperature–dependent resistivity/conductivity measurements are performed on the graphene/N-graphene sheets compressed in pellets. Different measurement configurations reveal directional dependence of current flow—the room-temperature conductivity longitudinal to the pellet’s plane is an order of magnitude higher than the transversal one, due to the preferential orientation of graphene sheets in the pellets. SEM imaging confirms that the graphene sheets are mostly oriented parallel to the pellet’s plane and stacked in agglomerates. The high longitudinal electrical conductivity with values on the order of 10 3 S/m should be noted. Further, the current flow mechanism revealed from resistivity-temperature dependences from 300K down to 10K shows non-metallic behavior manifested with an increasing resistivity with decreasing the temperature d ρ / d T < 0 usually observed for insulating or localized systems. The observed charge transport shows variable range hopping at lower temperatures and thermally activated behaviour at higher temperatures. This allows us to attribute the charge transport mechanism to a partially disordered system in which single graphene sheets are placed predominantly parallel to each other and stacked together.

The chemical interactions of two types of graphite and two types of carbon black (CB) with acetone, toluene, and phenol were studied in order to evaluate the influence of chemical treatment on the structure and morphology of the carbon phases. The experimental treatment of carbon phases was carried out at room temperature for 1 hour. The chemical and phase composition were studied by x-ray photoelectron (XP) and Raman spectroscopies, while the morphology and structure were determined by powder x-ray diffraction, as well as transmission electron microscopy techniques. To shed light on the most probable explanation of the observed results, we performed simulations and calculations of the binding energies of acetone, toluene, and phenol with model carbon phases: a perfect graphene sheet and a defective graphene sheet containing various structural defects (vacancies as well as zigzag and armchair edges). Simulations show that all non-covalent and most covalent coupling reactions are exothermic, with acetone coupling having the higher calorimetric effect. Based on the results of the simulations and the XP spectroscopy measurements, the probable reactions taking place during the respective treatments are outlined. The conducted studies (both theoretical and experimental) show that the treatment of graphite powders and CB with acetone, toluene, or phenol can be used as a preliminary stage of their modification and/or functionalization, including their conversion into graphene-like (defective graphene, reduced graphene oxide, and/or graphene oxide) phases. For example, the treatment of SPHERON 5000 with acetone significantly facilitates their subsequent modification with laser radiation to graphene-like phases.

The effect of modification of Cabot Corporation SPHERON 5000 carbon black suspended in bi-distilled water by laser irradiation (CuBr 2 laser with fundamental wavelength of λ = 511nm and 2 kHz repetition rate) has been studied. The carbon black suspensions were prepared by mixing 0.10 g carbon black previously treated with acetone in 100 ml bi-distilled water. Different laser beam fluencies and different irradiation times were used in order to optimize the modification process. The modified suspensions were decanted after sedimentation and dried. The powder fractions obtained were studied by scanning electron microscopy, X-ray diffraction and Raman spectroscopy.

Different nano-sized phases were synthesized using chemical vapor deposition (CVD) processes. The deposition took place on {001} Si substrates at about 1150–1160 °C. The carbon source was thermally decomposed acetone (CH3)2CO in a main gas flow of argon. We performed experiments at two ((CH3)2CO + Ar)/Ar) ratios and observed that two visually distinct types of layers were deposited after a one-hour deposition process. The first layer type, which appears more inhomogeneous, has areas of SiO2 (about 5% of the surface area substrates) beside shiny bright and rough paths, and its Raman spectrum corresponds to diamond-like carbon, was deposited at a (CH3)2CO+Ar)/Ar = 1/5 ratio. The second layer type, deposited at (CH3)2CO + Ar)/Ar = a 1/0 ratio, appears homogeneous and is very dark brown or black in color and its Raman spectrum pointed to defect-rich multilayered graphene. The performed structural studies reveal the presence of diamond and diamond polytypes and seldom SiC nanocrystals, as well as some non-continuously mixed SiC and graphene-like films. The performed molecular dynamics simulations show that there is no possibility of deposition of sp3-hybridized on sp2-hybridized carbon, but there are completely realistic possibilities of deposition of sp2- on sp2- and sp3- on sp3-hybridized carbon under different scenarios.

Here we present experimental results on the modification of graphite suspensions in bi-distilled water by laser irradiation in a flow mode system. The fundamental wavelength of a Nd:YAG laser system (λ= 1064 nm) was used in our experiments. The morphology of the sedimented and dried powders was studied by transmission electron microscopy (TEM). Their phase composition and structure were explored by Raman spectroscopy, GIXRD, as well as TEM.

In this paper electrical transport studies are performed on thin carbon films deposited on SiO 2 /Si substrates by pulsed laser deposition (PLD) applying laser ablation of micro-crystalline graphite target. Experiments were carried out on 320 - 420 nm thick SiO 2 on Si substrates as well as on hydrogenated diamond-like carbon (DLC) films deposited on SiO 2 /Si. Structural studies by means of XPS, SEM and Raman spectroscopy revealed that the films can be characterized as nano-sized carbon phases possessing different phase composition (i.e. the ratio sp 3 /sp 2 hybridized carbon, etc.). The electrical conductivity/resistivity of the films was measured in the temperature range 10 K < T < 300 K. Four-contact Van der Pauw method as well as two contact schemes have been applied. Some films have low room temperature resistivity in the range ρ = (0.1–1.5)×10 -3 Ω.·m and consist predominantly of sp 2 hybridized carbon with Raman spectra, which resemble that of nano-sized graphene depending on the deposition conditions and substrates used. The thinnest only 0.5 nm layer deposited directly on SiO 2 exhibits relatively low specific resistance (~10 -3 Ω. m), which can be taken as an indication of good deposition conditions of graphene-like layers. The current flow mechanism was explored at temperatures from 300 K down to 10K. The temperature dependence reveals non-metallic behavior - the conductivity decreases at decreasing temperature as opposed to typical metal behaviour. A model of variable range hopping (VRH) mechanism is applied to explain the low temperature conductivity drawn from transport in nanocrystalline disordered systems.

The present study investigates the possibility of obtaining graphene-like phases (defected graphene, graphene oxide, and reduced graphene oxide) as fine suspensions by applying a novel pulsed laser ablation (PLA) approach in flow mode. Two types of suspensions of microcrystalline graphite in aqueous suspensions and two types of microcrystalline graphite in suspensions of 6% hydrogen peroxide solution were irradiated in a quartz tube through which they flow. The third (λ = 355 nm) and fourth harmonics (λ = 266 nm) of an Nd:YAG laser system (15 ns pulse duration and 10 Hz pulse repetition rate) were used. The morphology of the obtained particles was studied by transmission electron microscopy (TEM). Their phase composition and structure were explored by X-ray photoelectron spectroscopy, X-ray diffractometry, and Raman spectroscopy.

The aim of the present research is to study some aspects of the carbon doping of TiO2 thin films and the influence of low temperature thermal annealing on the phase precipitation in thin films. Тhin films of heavily doped with carbon TiO2 (up to 3 at % C) were deposited on (15 × 25 × 1 mm) glass substrates by r.f. magnetron co-sputtering of TiO2 target and carbon plates on its erosion zone in Ar + air (residual pressure of 0.5 and 0.6 Pa, respectively) atmosphere. Two different process’s parameters were varied in different experiments in order to change the carbon content: the total area of the carbon plates which was 30, 84, 132, 400 and 830 mm2) and the radial distance between the center of the circle of the erosion zone with maximum rate of sputtering which was 2 and 4 cm. The as-deposited and annealed (air, 400°C, 1h) thin films with thickness of 110–150 nm were studied by ellipsometry, grazing incidence X-ray diffractometry (GIXRD), X-ray photoelectron spectroscopy, Raman spectroscopy, transmission and scanning electron microscopies. The GIXRD patterns reveal a mix of amorphous and nanocrystalline anatase and rutile TiO2 phases for all thin films. The Raman study confirms this conclusion but the TEM and GIXRD studies show presence of non-stoichiometric nanocrystalline phase based on Ti3C20O14 together with the other phases of TiO2-anatase, rutile and brookite. Similar charcterizations were carried out after annealing at 400°C in air for 60 min and the most prominent effects of thermal treatment are discussed.

Thin films of TiO 2 doped with carbon were deposited on 15×25×1 mm 3 glass substrates by r.f. magnetron co-sputtering of TiO 2 target and carbon plates on their erosion zone in Ar + air atmosphere (0.5 Pa and 0.6 Pa, respectively). Two different process parameters were varied in different experiments: the total area of the carbon plates (84 mm 2 , 560 mm 2 , 830 mm 2 or 1480 mm 2 ) and the radial distance from the center of the circle of the erosion zone with maximum rate of sputtering (2 cm or 4 cm). The as-deposited and annealed (air, 400 °C, 1 h) thin films with thicknesses of 40 - 60 nm were studied by ellipsometry, grazing incidence X-ray diffractometry (GIXRD), Raman spectroscopy, transmission (TEM) and scanning electron microscopies (SEM). The ellipsometric studies revealed the band gap, as well as the tail states and optical constants of the thin films obtained. The GIXRD patterns revealed a mix of amorphous and nanocrystalline anatase and rutile TiO 2 phases in all thin films. The Raman study confirmed this conclusion, but the TEM study showed the presence of some nanocrystalline C 20 O 14 Ti 3 , together with the other TiO 2 phases - brookite and nonstoichiometric TiOx phases (anatase and rutile). The effects of annealing at 400 °C in air for 60 min are also discussed.

Pure HfW2O8- and Ln3+-containing solid solutions, Hf1−xLnxW2O8−x/2 (Ln = Eu, Tm, Lu), were synthesized using the hydrothermal method. The lanthanide ions were selected based on the differences between their ionic radii. A content of the Ln3+ ions in the range of 0.01–0.15 mol with a step of 0.02 was used for Hf1−xLnxW2O8−x/2 preparation, although the main research was performed on x = 0.01 and 0.05 samples because of an inhomogeneity detected by powder X-ray diffraction (XRD) when the content of Ln3+ was above 0.07–0.09 mol. X-ray diffraction measurements were supported by Raman and infrared spectroscopy. A new band in the Raman spectra of the samples with 0.05 mol Ln3+, as well as a red shift of the most intensive band (assigned to valence stretching of W-O-W bonds) as a result of the Ln3+ presence, was detected. The Scanning Electron Microscopy and Transmission Electron Microscopy micrographs revealed well-crystalized microcrystals with lengths in the range of 2–5 μm, with larger interplanar distances, measured in the solid solutions of the same crystal plain. The alpha-HfW2O8 → beta-HfW2O8 order-to-disorder phase transition was followed by high temperature XRD, and its reversibility was evident. The influence of the Ln3+ both on the unit cell parameters of the solid solutions and on the temperature of phase transition and on the coefficient of thermal expansion, CTE, was observed. A band gap energy in the range of 2.8–3.1 eV for pure HfW2O8 and for the solid solutions Hf1−xLnxW2O8−x/2 (x = 0.01 and 0.05) was determined.

The aim of this work was to obtain graphene-like phases (defected graphene, graphene oxide and reduced graphene oxide) as fine suspensions by applying pulsed laser ablation (PLA) of micro-crystalline graphite suspension in water medium. The fundamental (λ = 1064 nm), second (λ = 532 nm), third (λ = 355 nm) and fourth harmonics (λ = 266 nm) of a Nd:YAG laser system (15-ns pulse duration and 10-Hz pulse repetition rate) were used. The morphology of the particles was studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Their phase composition and structure were explored by Raman and X-ray photoelectron spectroscopies, grazing incidence X-ray diffractometry (GIXRD) and TEM. The specimens were prepared by drop-casting on a glass substrate (for Raman and GIXRD studies) and on a standard TEM copper mesh for SEM and TEM examination.

Using RF magnetron sputtering, we deposited Bi1 2 TiO 20 (BTO) thin films on various substrates (glass, quartz, stainless steel (SS304), (001) and (111) Si and sital-ceramics, Al and Cu foils). The films had a constant thickness of 1.3 μm. The as-deposited films were studied by Raman spectroscopy, scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX), as well as by grazing incidence X-ray diffractometry (GIXRD). The GIXRD results reveal that the films are amorphous, while the Bi/Ti ratio varies between 9.5/1 and 11.8/1, as shown by the energy dispersive X-ray analysis (EDX). Further, the films deposited on glass and SS304 substrates were modified by laser irradiation (CuBr laser with a wavelength λ = 511 nm) to obtain an ordered cubic phase. The films deposited on quartz and on (001) and (111) Si substrates were thermally annealed at about 510 oC for three hours in ambient atmosphere. The modified films were characterized by Raman spectroscopy, scanning electron microscopy (SEM), EDX and X-ray diffractometry.

The aim of our work was to obtain graphene-like phases (defected graphene, graphene oxide and reduced graphene oxide) as fine suspensions by applying pulsed laser ablation (PLA) to microcrystalline graphite suspension in water medium. The fundamental (lambda = 1064 nm), second (lambda = 532 nm), third (lambda = 355 nm) as well as the fourth harmonic (lambda = 266 nm) of a Nd:YAG laser system, 15 ns pulse duration and 10 Hz pulse repetition rate were used in PLA processes. The morphology of the particles was studied by transmission electron microscopy (TEM). Their phase composition and structure were explored by Raman and X-ray Photoelectron spectroscopies, grazing incidence X-ray diffractometry (GIXRD) and high temperature powder X-ray diffraction (HTXRD) and TEM. It can be assumed, in accordance to the XPS, TEM and Raman studies, that the colloids obtained by all experiments contain predominantly rGO and defected graphene, but also some GO, graphite micro-particles, and graphene-like phases. Amorphous carbon is frequently observed in by PLA at lambda = 355 nm as well as at lambda = 266 nm at high laser beam fluences but it can be found in very small quantities in all specimens. The XPS analysis of the samples revealed a significant increment in the quantity of different oxygen-containing radicals as a function of the fluence, which is a result of the quantity of the sp(3)-hybridized carbon. Finally, the established PLA procedures have been found to be highly reproducible.

Hydrazones are key compounds for drug design and popular building blocks in the development of functional materials because of their simple structure, straightforward synthesis, hydrolytic stability, tendency toward crystallinity and tunable properties, etc. Hydrazones have been under study for a long time, but many of their electronic and structural properties (that can be attributed to the basic system structure) remain unexplored. In this paper the effect of substitution is studied for a set of selected aroylhydrazones – derivatives of the active chelator salicylaldehyde benzoyl hydrazone (SBH). The molecular structure of the compounds in nonpolar and polar media was characterized by DFT computations and vibrational (ATR-FTIR and Raman) spectroscopy. The radical scavenging ability of the compounds was tested towards stable free radicals as well as for inhibiting the iron induced oxidative stress in a lecithin containing model system. The possible mechanisms of antioxidant action were evaluated by DFT calculations in polar and nonpolar media. The most reactive sites for hydrogen atom abstraction and proton transfer were determined based on the calculated enthalpies required for the formation of hydroxyl and amide radicals and ionic species. The structural parameters and thermodynamic data for the studied compounds were correlated with the observed effects in the in vitro model systems in order to rationalize the influence of the nature and position of the substituent in the phenyl ring on the antioxidant properties.

The study aims to explore the effect of low fluence UV-C radiation on the structural quality of thin carbon films. We have modified single to few-layered nano-sized graphene-like films deposited by pulsed laser deposition (PLD) on similar to 300 nm SiO2/Si substrates and additionally different hydrogenated amorphous carbon a-C:H, tetrahedral amorphous carbon (a-C:H) and amorphous carbon (ta-C) thin carbon films. The modification was carried out by irradiation of the samples with UV-C lamps (Hg lamps lambda = 254 nm wavelength and fluence of about 2 x 10(-3) W/cm(-2)) for 5-30 min in air-atmosphere for graphene-like and up to 60 min for thin carbon films. The irradiated graphene-like films were oriented either at about 2 arcdeg to the impinging light, i.e. the light was almost parallel to the honey-comb plane of graphene film or perpendicular to the UV-C light. The thin carbon films were treated only by a light directed perpendicularly to the films' surface for 60 min. Films were studied before and right after UV-C modification by ellipsometry or profilometry, X-ray photoelectron and Raman spectroscopies to clarify the influence of the UV-C treatment. The most pronounced influence of the UV-C irradiation on the structural quality of the films was established on a-C:H and ta-C:H films where the sp(3) and the oxygen-containing radicals content decrease moderately and drops significantly, respectively. The influence of the UV-C irradiation directed almost parallel to the films' surface on the structural quality of the graphene-like films was slightly higher than that directed perpendicularly. No significant influence on the quality of a-C films synthesized or a-C:H films annealed at high temperatures (1020-1050) degrees C was observed.

We modified carbon black (CB) with a large surface area (ENSACO 350 GRANULAR) by acetone and further thermal treatment. The pristine and the modified CB were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD) and Raman spectroscopy. The acetone treatment increases the content of oxygen-containing radicals in CB. The thermal annealing was performed at temperatures ranging from 250 °C to 1080 °C for three hours in air atmosphere. The powder XRD patterns revealed that the broad complex peak centered at about 2θ = 24.7 – 24.8°, which arises from graphitic-ordered sp 2 -hybridized carbon, shifts to its usual position at 2θ = 26.2° as the annealing temperature is increased. We concluded that the above results pointed to a relative decrease in the number of 3D graphitic nano-crystals and an increase in the predominantly 2D ones. The Raman studies confirmed the above conclusions.