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High-yield, free-surface alternating field electrospinning (AFES) was effectively used in the fabrication of titanium oxide nanofibrous materials from the precursors based on titanium alkoxide and a blend of polyvinylpyrrolidone and hydroxypropyl cellulose. The alkoxide/polymer mass ratio in the precursor solution has significant effects on the precursor fiber production rate as well as the structure of resulting TiO2 nanofibers after thermal processing of precursor fibers at temperatures from 500 to 1000 °C. Within the range of tested process parameters, the best fiber production rate of ∼5.2 g h−1 was achieved, in terms of the mass of crystallized TiO2 nanofibers, with the precursor that corresponded to 1.5 : 1 TiO2/polymer mass ratio. TiO2 nanofibers produced by calcination at 500 °C for 3 h had 100–500 nm diameters and were composed of anatase (20–25 nm crystallite size) with rutile content 0.1–6.0 mol%, depending on the precursor composition. A considerable amount of anatase phase (up to 80 mol%) can be retained after thermal processing of TiO2 nanofibers at 750 °C for 3 h. A nanofibrous material composed of smooth and long, predominantly monocrystalline rutile, fibrous segments was produced at 1000 °C from the precursor with 2.5 : 1 TiO2/polymer mass ratio.

Catalytic systems based on bimetallic Pd-Au particles deposited on SiO2 were prepared by ultrasonically assisted water impregnation and used in the hydrogenation of furfural obtained by the acidic hydrolysis of waste biomass (brewery&rsquo, s spent grain) in aqueous phase. Pd-Au/SiO2 catalysts containing 50 g of Pd and 2&ndash, 100 g of Au per 1 kg of catalyst were characterized by high activity in the studied process and, depending on the Pd/Au ratio, selectivity to 2-methyloxolan-2-ol. The modification of 5%Pd/SiO2 by Au leads to the formation of dispersed Au-Pd solid solution phases, which was confirmed by XRD, XPS, ToF-SIMS, SEM-EDS, and H2-TPR techniques. The effect of dilution of surface palladium by gold atoms is probably crucial for modification of the reaction mechanism and formation of 2-methyloxolan-2-ol as the main product.

Cotton is grown in about 90 countries and accounts for 24% of the fibers used in the global production of textiles. In 2018/2019, 25.8 Mt of cotton were produced around the world. Since this natural product consists mainly of cellulose, it can be used as a raw material in the so-called “sugar economy”. This paper discusses a model procedure for thermally assisted acidic hydrolysis of cotton into glucose and subsequent oxidation of the glucose into calcium gluconate over Pd-Au/SiO2 catalyst. In the first step, H2SO4 was used as a catalyst for hydrolysis. The cotton hydrolysates were neutralized using CaCO3 and applied as a substrate in the second step, where glucose was oxidized over Pd-Au/SiO2 prepared by ultrasound assisted co-impregnation. With the appropriate Au/Pd molar ratio, small crystallites of palladium and gold were created which were active and selective towards the formation of gluconate ions. This approach to the transformation of glucose represents as a viable alternative to biological processes using fungal and bacterial species, which are sensitive to the presence of inhibitors such as furfurals and levulinic acid in hydrolysates.

Catalytic systems based on highly dispersed Pd nanoparticles deposited on SiO2 modified with PVP, AMPS and AcrAMPS were prepared and used in the hydrogenation of furfural obtained by the aqueous phase acidic hydrolysis of waste biomass (sugar beet pulp, sugar beet leaves, and brewing grain) from the food industry. Pd/PVP/SiO2 catalysts containing 50 g of Pd per 1 kg of catalyst were characterized by high activity in studied process, but lower selectivity to THFA in comparison to Pd/AMPS-SiO2 or Pd/AcrAMPS-SiO2 catalysts. The modification of SiO2 by PVP followed by the palladium catalyst loading, limited the adsorption of furfural by carbonyl group which probably leads to the improvement in THFA formation, which was confirmed by FTIR studies. The physico-chemical properties of the obtained palladium catalysts were investigated by XRD, CO chemisorption, TPR H2, TG-DTA-MS and BET techniques. The ICP-AES indicated no leaching of metal into the environment during furfural reduction, which confirms the stability of the Pd/PVP/SiO2, Pd/AMPS-SiO2 and Pd/AcrAMPS-SiO2 systems in the studied process.

The effect of iron introduction on the activity and selectivity of chemically precipitated supported palladium catalysts in the hydrodechlorination of 2,4-dichlorophenol in liquid phase at room temperature was studied. Bimetallic Pd–Fe catalysts supported on silica and alumina were characterized by using XPS, XRD, ToF-SIMS and TPR-H2 techniques. The dispersion of active phase in catalytic systems was examined by XRD and chemisorption of CO gas. Bimetallic Pd–Fe/SiO2 and Pd–Fe/Al2O3 catalysts containing 5 wt.% of Pd and 1–20 wt.% of Fe demonstrated high activity and high selectivity to phenol. However, Pd–Fe/Al2O3 catalysts with higher dispersion of the active phase were less active in the studied reaction than Pd–Fe/SiO2 systems, but selectivity to phenol was comparable for both types of bimetallic catalysts. The stability of Pd–Fe/SiO2 systems was higher than the bimetallic Pd–Fe/Al2O3 catalysts but selectivity to phenol decreases for that system systematically in each cycle of reaction, reaching only about 40% in the tenth cycle. It was also found that the addition of Fe to palladium catalysts limited the formation of cyclohexanone in the reaction medium.

Palladium catalysts promoted with a second metal demonstrate good activity and selectivity in many important oxidation and reduction reactions. The influence of co-metal on the catalytic performance of Pd depends on interaction between the two components and by the chemical state of both the Pd and co-metal. The understanding of the nature of such interaction is important in the optimization of such catalysts and development of new Pd-based catalyst systems with improved performance and stability. In this study, the surface structure and chemical states in several Pd–M/supported catalysts (where M = In, Bi, and Te) were experimentally investigated by using time-of-flight secondary ion mass spectroscopy (ToF-SIMS), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). It has been found that the formation of the intermetallic compounds and their composition can be responsible for a reduction or increase of catalytic activity and selectivity previously observed for the studied Pd–M systems.

Tungsten carbide-based coatings have been used in a wide variety of industrial applications such as high speed cutting tools, extrusion dies, drills, aerospace industries, and more. A few reports on ternary and quaternary coatings of WC with other elements indicate good prospects for these material systems. The present study focuses on the formation of quaternary WCeCreN and WCeAleN coatings during the simultaneous reactive RF-magnetron sputtering of tungsten carbide and Al or Cr targets in an argon/nitrogen gas mixture. The resulting coatings, with thicknesses of 3.5 mme8.2 mm, were characterized by using several analytical techniques including X-ray diffraction, SEM/EDS, AFM, and X-ray photoelectron spectroscopy. WCeCreN and WCeAleN coatings with high levels of tungsten (i.e. more than 50 at.% of the total metal content) demonstrated dense microstructure. Coatings with lower tungsten content formed columnar grain microstructure, with different surface morphologies depending on the process parameters. It was proposed that crystalline tungsten carbide (with partial N-substitution of C atoms) and chromium (or aluminum) nitride phases coexist in the coatings when the amount of tungsten was greater than 50 at.% of the total metal content; while at lower tungsten content, the dominating crystalline phase is either W-doped CrN1 y or AlN1 y solid solution, with WC1 x and small amounts of free sp2-bonded carbon present as X-ray amorphous phases.

Background Some loss of joint prostheses has been attributed to osteolytic phenomena leading to loosening and associated with debris from wear of polyethylene articulating against metal alloys. Reduced polyethylene wear has been reported with ceramics serving as an alternative counterface.

We discuss the mechanical properties and wear characteristics of sol–gel CaTiO 3 nanocrystalline ceramic coatings on titanium substrates. The structure and surface morphology of the coatings were investigated by X-ray diffraction, optical profilometry, and atomic force microscopy. The mechanical properties of CaTiO 3 coatings were characterized by using nanoindentation, scratch- and microwear-tests. The effect of titanium nitride intermediate layer on the improvement of the coating properties has been investigated. The best CaTiO 3 coatings with a TiN intermediate layer demonstrated the bonding strength up to 70 MPa, stability and low linear wear rate (∼ 1 μm per million cycles) during ball-on-disc reciprocal wear tests in micromotion (50–500 μm amplitude) with Ti6Al4V-alloy static partner at contact pressures up to 500 MPa in both dry and simulated body fluid environments.

Diamond is increasingly used in biomedical applications because of its unique properties such as the highest thermal conductivity, good optical properties, high electrical breakdown voltage as well as excellent biocompatibility and chemical resistance. Diamond has also been introduced as an excellent substrate to make the functional microchip structures for electrophoresis, which is the most popular separation technique for the determination of analytes. In this investigation, a diamond electrophoretic chip was manufactured by a replica method using a silicon mold. A polycrystalline 300 micron-thick diamond layer was grown by the microwave plasma-assisted CVD (MPCVD) technique onto a patterned silicon substrate followed by the removal of the substrate. The geometry of microstructure, chemical composition, thermal and optical properties of the resulting free-standing diamond electrophoretic microchip structure were examined by CLSM, SFE, UV-Vis, Raman, XRD and X-ray Photoelectron Spectroscopy, and by a modified laser flash method for thermal property measurements.

In a number of studies, the formation of perovskite CaTiO 3 (CTO) phase was observed at the interface layer when depositing hydroxyapatite coatings onto biomedical titanium alloys. Recently, CTO itself has been proposed as a suitable candidate for biocompatible coatings for medical implants, particularly Ti implants. We report on polycrystalline CaTiO 3 coatings prepared on silicon and titanium using a sol–gel technique followed by rapid thermal processing (RTP). The structure, composition, and surface morphology of CTO coatings RTP crystallized in the range of 500–800 °C for 30–180 s were investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and non-contact optical profilometry. Crystallization of single-phase CTO coatings on titanium is observed starting at 500 °C, while on Si, the coating remains amorphous at 550 °C, and an intermediate CaCO 3 phase is observed at up to 650 °C.

We studied the effect of ion damage on the properties of 50 keV Ga+ focused ion beam fabricated lead-zirconate-titanate capacitors as a function of the ion dose. We observed significant modification in the chemical composition of the damaged layer due to loss of lead and oxygen, and gallium impurity accumulation. The 5–10 nm thick damaged layer becomes dielectric after annealing and does not recover its ferroelectric properties. This dielectric layer substantially reduces the actual volume of the ferroelectric material in sub-100 nm structures, and can affect their performance.

This study investigates the effects of the addition of tungsten on the structure, phase composition, textural properties and activities of β-SiC-based catalysts in the aqueous phase hydrogenation of furfural. Carbothermal reduction of SiO2 in the presence of WO3 at 1550 °C in argon resulted in the formation of WxC-β-SiC nanocomposite powders with significant variations in particle morphology and content of WxC-tipped β-SiC nano-whiskers, as revealed by TEM and SEM-EDS. The specific surface area (SSA) of the nanocomposite strongly depended on the amount of tungsten and had a notable impact on its catalytic properties for the production of furfuryl alcohol (FA) and tetrahydrofurfuryl alcohol (THFA). Nanocomposite WxC-β-SiC catalysts with 10 wt % W in the starting mixture had the highest SSA and the smallest WxC crystallites. Some 10 wt % W nanocomposite catalysts demonstrated up to 90% yield of THFA, in particular in the reduction of furfural derived from biomass, although the reproducible performance of such catalysts has yet to be achieved.

Applications of diamond and amorphous carbon films in micro-mechanical and sensor elements often require formation of submicron size patterns. A focused beam of 50 keV Ga+ ions was used in this work to fabricate sub-100-nm patterns in bulk diamond, CVD diamond and amorphous carbon films. The influence of the focused ion beam (FIB) parameters and ambient gas on the sputtering yield, surface morphology and structure modification of these materials was studied using ion microscopy, atomic force microscopy (AFM), measurements of electric resistivity and Raman spectroscopy. Detailed results on FIB gas assisted etching (GAE) are reported. GAE processes with NH3+Cl2 and XeF2 were found to enhance the sputtering yield of diamond and ta-C films 4–7 times. The electric resistivity of FIB GAE patterned material is almost independent on the ion dose and it is of 1–2 orders of magnitude higher when compared to the electric resistivity of non-assisted FIB patterned material.

Amorphous hydrogen-free carbon films with various sp3/sp2 ratios were exposed to a 50 kV Ga+ focused ion beam (FIB) with a dose in the range from 1014 to 2.5×1018 ion/cm2. Atomic force microscopy (AFM), measurements of electric resistivity, and Raman spectroscopy were used to study FIB-induced modification of surface topography and film structure. The Raman spectra indicate an increase of sp2 coordination in sp3-rich films after ion irradiation and growth of sp2-bonded clusters under annealing at 550 °C. Light absorption in the FIB-exposed areas increases by a factor of up to 15 compared to the as-deposited material. For the FIB-irradiated sp3-rich films, the AFM measurements show neither significant roughening of the surface nor further modification of surface topography under annealing and over an extended period of time. The behavior of the films resistivity as a result of FIB irradiation and annealing most probably reflects the effect of gallium impurity. Also, the Raman measurements have documented s...

Cathodic arc discharge allows deposition of hydrogen-free quaziamorphous carbon films with a wide range of properties. The amount of sp3-bonded fraction can be up to 80 at.%, depending on the deposition conditions. This paper presents a summary of the characterization of carbon and carbon nitride thin films prepared by the cathodic arc discharge method operating in pulsed mode. The influence of the discharge parameters on the films structure and properties is described. Partial attention is paid to the analysis of films by Raman spectroscopy and atomic force microscopy. A comparison of results for different plasma sources design is conducted.

The surface morphology of C:N films deposited by a pulsed cathodic arc discharge (PCAD) method at nitrogen pressure in the range of 0.2–15 Pa was studied by atomic force microscopy (AFM). The roughness parameter R a was found to be changed from 0.25–0.30 nm for nitrogen-free film to 1.55–1.60 nm for C:N film with 40 at.% of the nitrogen content at P N 2 =1–2 Pa. The further increase of P N 2 up to 15 Pa results in locally non-uniform surface morphology. It is assigned to the formation of a polymeric phase in the film. The correlation of the surface morphology and chemical bonding in PCAD C:N films is discussed.

Nitrogenated carbon films with N/C ratio up to 0.65 have been prepared by a filtered pulsed cathodic arc discharge (PCAD) method at nitrogen pressure in the range 0.1–15 Pa. The influence of the process parameters and nitrogen pressure on the growth rate, chemical composition and quality of C:N films has been studied. The maximum N/C ratio was found at a gas pressure of 1–2 Pa. Raman study of films prepared at nitrogen pressure higher than 2 Pa showed a strong increase of the photoluminescence signal with a maximum at 2.2 eV.

Palladium catalysts promoted with a second metal demonstrate good activity and selectivity in many important oxidation and reduction reactions. The influence of co-metal on the catalytic performance of Pd depends on interaction between the two components and by the chemical state of both the Pd and co-metal. The understanding of the nature of such interaction is important in the optimization of such catalysts and development of new Pd-based catalyst systems with improved performance and stability. In this study, the surface structure and chemical states in several Pd–M/supported catalysts (where M = In, Bi, and Te) were experimentally investigated by using time-of-flight secondary ion mass spectroscopy (ToF-SIMS), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). It has been found that the formation of the intermetallic compounds and their composition can be responsible for a reduction or increase of catalytic activity and selectivity previously observed for the studied Pd–M systems.

The purpose of the present study was to investigate the properties of a carbon layer depending of the origin of applied methods. Quasiamorphous carbon coatings prepared by ion beam methane decomposition by RF dense plasma and vacuum pulsed arc deposition were applied to stainless steel implants used in surgery. The studies of carbon films as coatings for implants in surgery were aimed on the investigations of biological resistance of implants, histopathological investigations using laboratory animals, tests of corrosion resistance, measurements of mechanical properties and a breakdown test in Tyrod solution. The comparison of the properties of the coating produced by these methods shows very good biotolerance and biocompatibility of all of the coatings. They are not corroded in physiological fluids. From the other side they have different properties, especially electrical and optical, and are not influenced on medical applications. The obtained results prove that the implants coated by all the methods mentioned are a very good material for medical use.

Gold nanoparticles with shapes which varied from spheres to multipods and polygons were prepared with a seedless approach in water/methanol mixtures in the presence of polyvinyl alcohol using sodium ascorbate as the reducing agent. The shape of Au nanoparticles is critically affected by the water/methanol ratio, as well as by the ratio of hydrogen tetrachloroaurate (HAuCl4) to sodium ascorbate and the concentration of HAuCl4 in the reaction mixture. A decreased ratio of water to methanol below 30/70 leads to the formation of multi-branched nanoparticles with the size in the range of 30-70 nm at relatively low HAuCl4 concentration, whereas polygons are formed when HAuCl4 concentration increases. The polyvinyl alcohol stabilized multi-branched Au nanoparticle colloids were stable at room temperature for a period of at least six-month.

Focused ion beams (FIBs) provide maskless prototyping of 2-D and 3-D micro- and nano-structures for many applications in optics, electronics, and medicine. In many situations, the chemical enhancement of the FIB sputtering process is used to increase the selectivity and removal rate of different materials.In this study, Ti, TiO2, and TiN thin films of different origin were patterned using Ga+ FIB without or with chemical enhancement (or gas assisted etching, GAE). The effects of ion beam parameters and gas ambient on the sputtering yields, etching selectivity, roughening at the film/substrate interface, sub-micron and nano-scale patterning of these materials were investigated.Several gases, including XeF2, CO2, chlorine, bromine, and oxygen, were employed. The largest increase of the sputtering yield was achieved with XeF2 gas, whereas CO2 and oxygen depleted the sputtering rate. Among all gases tested, the Br2 FIB GAE produced the best uniformity of the material removal. It was found that the use of bromine gas provides the best selectivity between the titanium oxide and pure titanium or its nitride.

Interest in diamond-like carbon (DLC) thin films has increased considerably in the last few years. It is suggested that DLC films may be used for electronic devices, especially working at high temperatures. The subject of this contribution is the electrical conduction of a metal/DLC/ Si system. The investigated DLC films were prepared by two methods: radio-frequency plasma chemical vapour deposition (RF-PCVD) and pulsed cathodic-arc discharge (PCAD) on silicon substrates. The metal/DLC/silicon heterojunctions show rectifying characteristics. The rectifying character of the current-voltage behaviour may be caused by a thin Interfacial SiO2 sublayer existing between the DLC film and silicon.

This chapter discusses fabrication, characterization, and postprocessing of cathodic-arc-derived hydrogen-free tetrahedral amorphous carbon. Preparation of carbon films with physical properties and short range order structures—varying in the range from those of graphite to diamond—has been achieved with the use of several deposition techniques based on the cathodic arc discharge. This understanding has enabled the optimization of the process to yield films with controlled properties. The film structure is generally characterized by the ratio of the sp 3 - to sp 2 -bonded fractions. The film properties depend on the medium- and short-range order structure and the sp 3 or sp 2 ratio. The properties of cathodic-arc-deposited impurity-free carbon films are governed by their short-range order structure. Finally, several technological issues are still needed to improve the applicability of cathodic-arc-derived carbon film. The efforts undertaken by research groups have brought a general understanding of the main processes involved in the carbon film growth and the structure formation.

In modern photolithography mask repair, shorter exposure wavelengths, smaller dimensions, and tighter process latitudes pose new challenges. We have systematically investigated focused ion beam (FIB) gas assisted etching (GAE) of chrome and mask transmission at 193 nm ultraviolet (UV) irradiation for various FIB parameters. The gases, used either alone or in binary combinations, include XeF2, Cl2, NH3, CO, CO2, Br2, H2O, and O2. While the bromine GAE appears to be the most effective among single gases in etching chrome, the quartz transmission after chrome removal remains ∼50% compared with unexposed material, and residue is present. The gas mixtures NH3/Br2 and CO2/Br2 were found to reduce the amount of residue and to enhance the chromium mask etching rate compared to Br2-only etching. This enhancement occurs in a narrow range of gas partial pressures, and the FIB process may need to be optimized further. The best transmission at 193 nm UV irradiation of the FIB GAE repaired regions achieved to date with...

Superconformal electrodeposition of copper in 500 nm deep trenches ranging from 500 to 90 nm in width has been demonstrated using an acid cupric sulfate electrolyte containing chloride (Cl), polyethylene glycol (PEG), and 3‐mercapto‐l‐propanesulfonate (MPSA). In contrast, similar experiments using either an additive‐free electrolyte, or an electrolyte containing the binary combinations Cl‐PEG, Cl‐MPSA, or simply benzotriazole (BTAH), resulted in the formation of a continuous void within the center of the trench. Void formation in the latter electrolytes is shown to be reduced through the geometrical leveling effect associated with conformal deposition in trenches or vias with sloping sidewalls. The slanted sidewalls also counterbalance the influence of the differential cupric ion concentration that develops within the trenches. Examination of the i-E deposition characteristics of the electrolytes reveals a hysteretic response associated with the Cl‐PEG‐MPSA electrolyte that can be usefully employed to monitor and explore additive efficacy and consumption. Likewise, resistivity measurements performed on corresponding blanket films can be used to quantify the extent of additive incorporation and its influence on microstructural evolution. The films deposited from the Cl‐PEG‐MPSA electrolyte exhibit spontaneous recrystallization at room temperature that results in a 23% drop in resistivity within a few hours of deposition. © 2000 The Electrochemical Society. All rights reserved.

Carbon nanostructures, e.g., nanotubes, fullerenes, carbon blacks, etc., are being extensively explored for numerous biomedical applications. The most of such studies, however, deal with carbon nanotubes, and comparatively less is known on the biomedical potential of other nanosize carbon particles. In the present work, carbon and metal/carbon core/shell spherical nanoparticles have been prepared using the decomposition of monosaccharide-based compositions under hydrothermal conditions with or without the presence of metal seed particles. The effects of different process conditions on the particle size, structure, and composition have been examined using TEM, XRD, UV-Vis, FTIR and Raman spectroscopies. The nearly perfect spherical particles with the dimensions in the range of 20 – 100 nm have been obtained depending on the process parameters such as precursor concentration, presence of seed particles and polymeric additives, process temperature and time. The particles prepared with 5 – 20 nm gold seeds clearly showed the core/shell structure with the thickness of carbon shell in the range of 10 – 50 nm. The FTIR experiments have indicated a strong effect of the processing conditions on the chemical activity of nanoparticle surfaces in the attachment of the additional surface functional groups and organic molecules. It has been found that the both hydrothermally prepared carbon and metal/carbon core/shell nanoparticles possess very good dispersibility and stability in the both water and simulated body fluids in the most of experiments. The particles have been successfully functionalized with several molecules such as polyethyleneglucol and biotin. Selected samples of well-dispersed carbon nanospheres with different concentrations have been tested for their interaction with several cultured cell lines including epidermal keratinocytes, fibroblasts, and dog macrophages.