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From a glass with the mol% composition 20.1 Na2O-3 Al2O3-23.1 BaO-23 TiO2-7.6 B2O3-17.4 SiO2-5.8 Fe2O3 cubic barium titanate was crystallized. Scanning and transmission electron microscopy micrographs of the prepared glass-ceramics show fine crystals agglomerated to globular particles. With increasing crystallization time, their volume concentration increases and the particles form interconnected aggregates. From electrical impedance measurements of selected glass ceramics, the electrical conductivity and the dielectric permittivity of the prepared materials were determined for temperatures from −-170 °C to 97 °C, and frequencies from 100 Hz to 100 kHz. The typical values of the resistance are in the order of 108 Ω and the dielectric constants in the order of 40 at 100 kHz at room temperature. The two diffuse relaxor type phase transitions observed from −-123 to −-73 °C and from −-33 to 0 °C are attributed to the transformation rhomboherdral - orthorhombic and orthorhombic - cubic BaTiO3, respectively.

Formaldehyde (HCHO) is recognized as one of the most emitted indoor air pollutants with high detrimental effect on human health. Significant research efforts are focused on HCHO removal to meet emission regulations in an effective and economically profitable way. For over three decades, the unique electronic properties and catalytic abilities of nano-gold catalysts continue to be an attractive research area for the catalytic community. Recently, we reported that mechanochemical mixing is a relevant approach to the preparation of Co-Ce mixed oxides with high activity in complete benzene oxidation. A trend of higher surface defectiveness, in particular, oxygen vacancies, caused by close interaction between cobalt oxide and cerium oxide phases, was observed for a mixed oxide composition of 70 wt.% Co3O4 and 30 wt.% CeO2. These results directed further improvement by promotion with gold and optimization of mixed oxide composition, aiming for the development of an efficient catalyst for room temperature HCHO abatement. Support modification with potassium was studied; however, the K addition caused less enhancement of HCHO oxidation activity than expected. This motivated the preparation of new carrier material. In addition to Co3O4-CeO2 mixed metal oxides with preset ratio, γ-Al2O3 intentionally containing 33% boehmite and shortly named Al2O3-b was used for synthesis. Analysis of the role of support composition in HCHO oxidation was based on the characterization of nano-gold catalysts by textural measurements, XRD, HRTEM, XPS, and TPR techniques. Gold supported on mechanochemically treated Co3O4-CeO2-Al2O3-b (50 wt.% Al2O3-b) exhibited superior activity owing to high Ce3+ and Co3+ surface amounts and the most abundant oxygen containing species with enhanced mobility. This catalyst achieved oxidation to CO2 and H2O by 95% HCHO conversion at room temperature and 100% at 40 °C, thus implying the potential of this composition in developing efficient catalytic materials for indoor air purification.

Pulsed laser deposition (PLD) of thin carbon films on SiO2/Si substrates was performed and the resulting films were examined by X-ray photoelectron spectroscopy, transmission electron microscopy (TEM), Raman spectroscopy and ellipsometry. The deposition process was accomplished by laser ablation with Nd:YAG laser (third harmonic λ = 355 nm, pulse width τ = 18 ns and a repetition rate of 10 Hz) on 320–420 nm SiO2/(001) Si substrates with surface area of 15 × 15 mm2. The laser ablation process was carried out in two different deposition regimes: i) continuous regime with a deposition time of 15–1800 s; and (ii) pulse mode. As a target, carbon microcrystalline graphite disks (OD 15 mm, thickness 0.5 mm) were used. We established that films consisting of graphite nanoparticles/graphene grains of 5 to 30 nm thickness were deposited by the continuous PLD process while films comprising one to few-layered nano-sized graphene were deposited by pulsed PLD. Some films have low resistance (ρ = (0.1–1.5) × 10−3 Ω·m) and consist predominantly of sp2 hybridized carbon with Raman spectrum, which resembles that of nano-sized graphene. Regardless of the PLD process used, we observed an interface film enriched with sp3 hybridized carbon, which could be related to C O, C H and other interface bonds.

Electrоdeposited Zn–Cr alloy coatings, containing 3.6, 5.4 and 9.4 mass % Cr were analysed by DSC and XRD. X-ray diffraction patterns of the samples show that when they are annealed to sele...

In this work, we report fabrication of highly porous metal-oxide nanostructures by pulsed laser deposition performed in air at atmospheric pressure. The attention was focused on the structure, morphology, and composition of ZnO, TiO2, SnO2 and MoO3 metal oxides. The technology applied leads to formation of nanostructures composed by nanoparticles. Additionally, a nanocomposite sample consisting of metal-oxide and noble-metal nanoparticles was fabricated. The nanostructures were produced in view of applications as gas sensors. Preliminary results on the gas-sensing properties of the metal-oxide nanostructures are reported.

Pyridinium hydrogen sulfate ionic liquid (PHS) heterogenized on activated carbon (AC) is investigated for the first time in the current paper. For that purpose, the xPHS/AC (x = 8, 17, 33 and 66 wt%) samples are analyzed by a number of physicochemical methods such as N2 adsorption–desorption measurements, X-ray diffraction, X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. Catalytic activity and reusability of xPHS/AC are evaluated in the reaction of butyl acetate synthesis. Effect of the reaction temperature and catalyst loading on the butyl acetate yield are examined in this work as well. Important thermodynamic parameters such as equilibrium constant, activation energy, Gibbs free energy and activation energy barrier for the reaction of butyl acetate synthesis in the presence of xPHS/AC are determined. Textural characterization revealed the that xPHS/AC are mixed micro-mesoporous materials. The PHS heterogenization on AC affects both ionic liquid and support phases due to a surface PHS–AC interaction. FT-IR and XPS showed that this interaction is: (i) manly expressed as a close contact between the pyridinium cation and the functional groups on the AC surface and (ii) electrostatic in nature. The existence of a PHS–AC interaction is found to be responsible for the formation of surface PHS particles of various size. However, the catalytic activity of xPHS/AC is established to be affected by the surface active phase amount, but not the PHS particle size.

The presence of triple phase TiO2 new mixture (Magneli of higher order homologous series, brookite and anatase) containing P dopant ensures positive changes in the structure, in the phase composition and in the chemical composition. These changes explained the reasons for the enhanced UV/Vis photocatalytic efficiency towards oxidative degradation of ethylene and acetylsalycylic acid. The samples were characterized by a set of methods: Raman spectroscopy, Scanning Electron Microscopy (SEM), Diffuse-Reflectance Spectroscopy (DRS), Differential Thermal Analysis (DTA-TG), X-ray Photolelectron Spectroscopy (XPS), Transmission Electron Microscopy and High-Resolution Transmission Electron Microscopy (TEM/HRTEM), Electron Paramagnetic resonance (EPR) and X-ray Diffraction (XRD) analyses. The combination of the optimal set of values of Ti3+, oxygen radicals and vacancies, Ti-O-P bonds, narrower band gap is responsible for the higher quantum yield due to the increased number of charge carriers, while the unique phase mixture prevents the recombination of charge carriers. These factors guarantee enhanced rate of the photocatalytic reaction, and extended response to the visible light region.

In this work, we demonstrate a novel way of fabricating oriented composite nanowires consisting of arranged nanoparticles. The structures are produced by an advanced pulsed laser deposition technology involving the simultaneous ablation of two metal targets, Fe and Ag. The depositions are carried out in air at atmospheric pressure in the presence of a magnetic field by using nanosecond laser pulses delivered by a Nd:YAG laser system operating at its fundamental wavelength. Samples are thus produced composed by iron oxide and silver at different percentage ratios. Their morphology represents nanowires with few tens of microns in length and an orientation predominantly following the direction of the magnetic force lines. The study on the optical properties of the structures thus produced revealed plasmon resonance behavior in their transmission spectra with its position depending on the ratio between the two building materials. UV–vis spectra were also obtained with polarized light. Higher transmission was measured for light polarized perpendicular to the length of the nanowires, compared to the case of polarization parallel to the nanowires. The structures can find applications in the design of novel polarization and magneto-optics devices, as well as in nanoelectronics and spintronics.

Considerable efforts to reduce the harmful emissions of volatile organic compounds (VOCs) have been directed towards the development of highly active and economically viable catalytic materials for complete hydrocarbon oxidation. The present study is focused on the complete benzene oxidation as a probe reaction for VOCs abatement over Co3O4-CeO2 mixed oxides (20, 30, and 40 wt.% of ceria) synthesized by the more sustainable, in terms of less waste, less energy and less hazard, mechanochemical mixing of cerium hydroxide and cobalt hydroxycarbonate precursors. The catalysts were characterized by BET, powder XRD, H2-TPR, UV resonance Raman spectroscopy, and XPS techniques. The mixed oxides exhibited superior catalytic activity in comparison with Co3O4, thus, confirming the promotional role of ceria. The close interaction between Co3O4 and CeO2 phases, induced by mechanochemical treatment, led to strained Co3O4 and CeO2 surface structures. The most significant surface defectiveness was attained for 70 wt.% Co3O4-30 wt.% CeO2. A trend of the highest surface amount of Co3+, Ce3+ and adsorbed oxygen species was evidenced for the sample with this optimal composition. The catalyst exhibited the best performance and 100% benzene conversion was reached at 200 °C (relatively low temperature for noble metal-free oxide catalysts). The catalytic activity at 200 °C was stable without any products of incomplete benzene oxidation. The results showed promising catalytic properties for effective VOCs elimination over low-cost Co3O4-CeO2 mixed oxides synthesized by simple and eco-friendly mechanochemical mixing.

We report on the fabrication of highly porous metal-oxide nanostructures by pulsed laser deposition performed in air at atmospheric pressure. The depositions were performed by ablating synthesized ZnO and a mixed target of ZnO and TiO2 as initial materials. The attention was focused on the structure, morphology, optical and photocatalytic properties of the as-deposited nanostructures of the ZnO-TiO2 system. The technology applied leads to the formation of nanostructures composed of nanoparticles. The as-prepared samples possess a high transmittance in the visible and near IR region with an optical band gap in the range of 3.1 - 3.2 eV. It was demonstrated that the as-deposited ZnO and ZnO-TiO2 nanostructures degrade Rhodamine B up to 43 - 44% after 300-min UV irradiation.

The use of laser processing for the creation of diverse morphological patterns onto the surface of polymer scaffolds represents a method for overcoming bacterial biofilm formation and inducing enhanced cellular dynamics. We have investigated the influence of ultra-short laser parameters on 3D-printed poly-ε-caprolactone (PCL) and poly-ε-caprolactone/hydroxyapatite (PCL/HA) scaffolds with the aim of creating submicron geometrical features to improve the matrix biocompatibility properties. Specifically, the present research was focused on monitoring the effect of the laser fluence (F) and the number of applied pulses (N) on the morphological, chemical and mechanical properties of the scaffolds. SEM analysis revealed that the femtosecond laser treatment of the scaffolds led to the formation of two distinct surface geometrical patterns, microchannels and single microprotrusions, without triggering collateral damage to the surrounding zones. We found that the microchannel structures favor the hydrophilicity properties. As demonstrated by the computer tomography results, surface roughness of the modified zones increases compared to the non-modified surface, without influencing the mechanical stability of the 3D matrices. The X-ray diffraction analysis confirmed that the laser structuring of the matrices did not lead to a change in the semi-crystalline phase of the PCL. The combinations of two types of geometrical designs—wood pile and snowflake—with laser-induced morphologies in the form of channels and columns are considered for optimizing the conditions for establishing an ideal scaffold, namely, precise dimensional form, mechanical stability, improved cytocompatibility and antibacterial behavior.

The paper presents experimental results on fabricating composite nanostructures consisting of magnetic and non-magnetic metal oxide nanoparticles. The samples were produced by a single-step process of pulsed laser deposition carried out in air at atmospheric pressure in the presence of a magnetic field. Part of the depositions was performed by ablation of two metals simultaneously – Fe and Zn, and Fe and Ti. Another part of the experiments included simultaneous depositions from metal oxide targets – Fe2O3 and ZnO, and Fe2O3 and TiO2 as well as from metal and metal oxide (Fe-TiO2) targets. The depositions were performed in a magnetic field in order to control the magnetic nanoparticles produced in the plasma plume and thus, the morphology of the composite nanostructures. The structure and morphology of the structures obtained were studied as related to the samples’ composition. It was found that the difference in the ablation threshold of the initial ablated materials determines the use of a specific methodology for composite fabrication. The nanostructures prepared could be used in the design of novel magneto-optic and sensor devices.

A B S T R A C T Glass-ceramics with cubic BaTiO3 as a major and hexagonal BaTi1-xFexO3-δ as a second phase were prepared by crystallization at 560 °C in a glass with the composition 20.1Na2O/23TiO2/23.1BaO/3Al2O3/7.6B2O3/17.4SiO2/ 5.8Fe2O3. X-ray photoelectron spectroscopy revealed presence of Ti4+ and Fe3+ ions in tetrahedral and octahedral coordination. Ba2+ occurs in different environments depending on the thermal history of the samples. The numbers of bridging and non-bridging oxygens vary with the crystallization time. Electron paramagnetic resonance spectroscopy showed four types of Fe3+ ions that are non-uniformly distributed in the samples: Fe3+ ions in magnetic domains, isolated Fe3+ in a rhombic crystal field, magnetically coupled Fe3+ ions in BaTiO3 and Fe3+ ions located in a crystalline phase. The ratio between the described types of Fe3+ ions depends on the annealing time. Mössbauer spectroscopy detected Fe3+ tetrahedral and octahedral coordinated in the glass. Fe3+ was incorporated in distorted octahedral and pentahedral coordination in the Ti4+ sites of hexagonal BaTiO3 crystals, the electroneutrality being preserved by the occurrence of oxygen vacancies. Vibrating sample magnetometer measurements were used to determine ferromagnetic properties in samples crystallized for times ≥ 3 h. Maximum magnetization of 0.8 emu/g and a coercive force of 25 Oe were determined for the sample crystallized for 3 h at 560 °C.

A laser-based technology is presented for fabrication of oriented nanowires composed by nanoparticles. The nanowires were produced by nanosecond pulsed laser deposition in air at atmospheric pressure in the presence of an external magnetic field. The technology described is relevant to the preparation of nanowires of magnetic materials. Applying an external magnetic field during the deposition resulted in the formation of nanowires with lengths of a few microns oriented longitudinally to the magnetic field lines. The influence was investigated of the process parameters, namely, laser fluence, target-substrate distance, and wavelength used for ablation, on the morphology of the deposited samples. It was found that the degree of the nanowires’ orientation increased with the increase of the target-substrate distance. Also, the density of the deposited material was influenced by the laser fluence applied and by the wavelength used.

Hazardous residues from ferronickel production and glass cullet were mixed and vitrified. After low-cost heat-treatment the obtained glass was transformed in a fine-crystalline glass-ceramic. The evolution of structure during the crystallization cycle is studied by XRD and SEM-EDS. Finally, the morphology of final glass-ceramic was elucidated by TEM and FESEM. Due to the elevate amounts of iron and magnesium oxides and the presence of ∼2 wt % chromium oxides in the composition, the crystallization process is peculiar and the final structure of glass-ceramic is complex. Some preliminary Fe-Mg-Cr spinel crystals with size of few microns precipitate during the melt cooling. Then, these crystals act as centres for the growth of a pyroxene phase; thus, 15–20 vol% of the glass-ceramic structure is formed. The major amorphous phase, where Cr2O3 concentration becomes negligible, is characterized with a high immiscibility trend, leading to the formation of Fe-rich droplets with size of 50–70 nm. Subsequently, these droplets are transformed into nano magnetite crystals, which provoke crystallisation of the main pyroxene phase. This “second” new pyroxene phase differs by the one, already formed on the preliminary Fe-Mg-Cr spinel, and is composed by mono-crystals with size of 150–200 nm.

Glasses were prepared in the system (100 − x)(0.16Na2O/0.10MnO/0.74SiO2)/xFe2O3 (x = 15 and 25 in mol%) by the traditional melt-quenching technique. Some of them were subsequently crystallized at temperatures in the range from 520 to 700 °C for times from 10 min to 100 h. The valence states of Fe and Mn in selected glasses and glass-ceramics were investigated by X-ray photoelectron spectroscopy (XPS) and showed the presence mostly of Mn2+ while Fe occurs as both Fe2+ and Fe3+. X-ray diffraction (XRD) analyses of the 15 mol% Fe2O3 samples revealed that at lower temperatures and for short heat treatment times a solid solution with a spinel structure and a chemical composition between MnFe2O4 (jacobsite) and Fe3O4 (magnetite) crystallizes, while aegirine (NaFe(SiO3)2) additionally occurs at higher temperatures and for longer annealing times. Here the average crystallite size of the jacobsite-based phase varies between 4 and 10 nm, as determined by XRD. The XRD analysis of the 25 mol% Fe2O3 samples which spontaneously crystallize when quenching the melt only show the precipitation of the jacobsite–magnetite solid solution. The microstructure was investigated by scanning and transmission electron microscopy (SEM and TEM) as well as electron-backscatter diffraction (EBSD). The EBSD analyses show that the cubic crystals grow via the polygon as well as the dendritic growth mechanisms. The individual grains show independent orientations and inclusions of residual glass while a global crystallographic texture could not be detected. The obtained magnetization curves of the 25 mol% Fe2O3 samples show hysteresis and a Curie temperature of approximately 480 °C which supports the XRD results. The samples with 15 mol% Fe2O3 crystallized at 650 and 700 °C exhibit superparamagnetic behaviour and thin S-shaped magnetization curves with zero coercivity.

In this paper, we present an original study on metamorphic GaAsSb layers grown by liquid phase epitaxy (LPE) on GaAs substrates for photovoltaic applications. To ensure a controlled growth of the layers with reproducible composition and properties a low-temperature (below 600 °C) variant of LPE was used combined with a precise choice of the technological conditions. This allowed obtaining layers with ∼8% Sb in the As sublattice. The crystal structure, composition, surface morphology, local arrangement and chemical bonding of Sb in the obtained layers were investigated by a variety of measurement methods including X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, atomic force microscopy, X-ray photoelectron spectroscopy and Raman spectroscopy. Hall-effect measurements were performed in the temperature range of 80–300 K to clarify the influence of defects on the transport properties. Temperature-dependent photoluminescence spectra at low excitation power were measured to evaluate the optical quality and identify localized states in the grown layers. The optical absorption properties and the transport of the photogenerated carriers in the grown samples were investigated using surface photovoltage (SPV) spectroscopy at room temperature. The SPV measurements have shown that the long-wavelength photosensitivity of the GaAsSb layers is extended down to 1.2 eV.

We present a microstructural study of nanocomposite samples based on iron oxide and a noble or a transition metal. The samples were produced by laser ablation in air at atmospheric pressure in the presence of a magnetic field. This technology allows production of oriented nanowires composed by nanoparticles. We applied a simultaneous laser ablation of two targets in an external magnetic field. The targets used for the ablation were a magnetic material (iron) and a noble or a transition metal (silver, gold or cobalt). The presence of a magnetic field during the deposition results in arranging the nanoparticles formed in the plasma plume into micrometric nanowires on the substrate. The structural analyses confirms that the samples are composed by iron oxide and a noble or a transition metal.

Transparent and conductive thin films of As-doped In2O3 have been deposited on glass and silicon substrates by spray pyrolysis technique using InCl3 and 3As2O5.5H2O as starting materials. The films obtained were characterized by X-ray diffraction, UV-VIS spectroscopy, scanning electron microscopy and atomic force microscopy. The effects of As concentration on the resistivity and optical transmission of the films have been investigated. The application of the films in position sensitive structures Si-SiO2-In2O3 acting on the base of lateral photoeffect has been examined.

In this work, we present fabrication and studies of pure and Pd-decorated ZnO nanostructures on Ag-coated substrates in view of gas-sensing application. The sensor elements consist of a dense structure of ZnO nanobelts. The chemical composition of the surface and gas-sensing properties of pure and Pd-doped nanostructures were studied and compared. On the surface of the Pd-decorated ZnO samples, the presence was found of Pd and Pd-Ag clusters, as well as isolated Pd2+ ions were incorporated into the ZnO lattice. The Pd-ZnO sensor element showed a better response to CO, NH3, and acetone compared to the pure ZnO sample. The Pd-ZnO sample exhibited its highest response to exposure to acetone at room temperature. We associate the improvement of sensing performance of the Pd-decorated ZnO nanostructures with the increased number of adsorption centers on the surface due to the Pd nanoparticles.

Glasses with the mol % composition 20.1Na2O/23TiO2/23.1BaO/3Al2O3/7.6B2O3/17.4SiO2/5.8Fe2O3 were synthesized. During heat treatment at 550°C for 5 min to 7 h, cubic BaTiO3 crystallized. The microstructure of the glass-ceramics was studied by scanning electron microscopy. The average size of the crystalline particles varied from 190 to 790nm, depending on the crystallization time. Impedance measurements of selected glass-ceramics at temperatures from -183 to 97°C using frequencies from 100Hz to 1MHz witness insulating properties. The ac-conductivity at 100Hz increases with temperature from 10−10 S/m at -183°C to 10−6 S/m at 97°C. The ac-conductivity is established predominantly in the glass phase with Na+-ions as charge carriers and could be well fitted by the universal as well as by the modified Jonscher power law. However, for the intermediate temperature range, the modified Jonscher equation seems to better explain the physical mechanisms of conduction dispersion with frequency. In the whole studied temperature range, the power “s” in the dispersion equation slightly varies with the glass-ceramics’ thermal history but shows a relatively large decrease with increasing temperature. The higher conductivity of the sample with the highest BaTiO3 volume fraction is associated with the lowest s-value and largest number of non-bridging oxygen ions in the structure.

A glass with the composition 20.1Na2O·23.1BaO·23TiO2·9.8B2O3·21SiO2·3Al2O3 (in mol%) was synthesized using a traditional glass melting technique. Its thermal properties were characterized by differential thermal analysis (DTA), and appropriate time–temperature schedules were applied in order to prepare glass-ceramics containing barium titanate. X-ray diffraction (XRD) analysis showed the formation of cubic barium titanate and fresnoite at an annealing temperature of 650 °C and for times t ≥ 3 h, while annealing for 1 h resulted in the sole crystallization of barium titanate. Supplying longer crystallization times resulted in the additional formation of increasing fresnoite concentrations. The crystallization behavior of the glass is characterized using electron microscopy techniques, i.e. energy dispersive X-ray spectroscopy (EDXS) and electron backscatter diffraction (EBSD), which reveal the simultaneous growth of fine, densely-branched barium titanate and fresnoite crystals.

Alumina supported Cu–Mn mixed oxide with Cu/Mn molar ratio 2:1 was used as a support of gold and silver catalysts for oxidation of CO, methanol and dimethylether. Different techniques (XRD, HRTEM, XPS, FTIR, EPR, and TPR) were used to investigate structure–reactivity relationship. A strong effect of the nature of the promoters on the catalytic behaviour was observed. Superior catalytic activity in oxidation of CO was measured after addition of Au, while modification by Ag affected very slightly the CO oxidation activity of Cu/Mn 2:1 sample. Both Au and Ag have beneficial effect on CH3OH oxidation activity of Cu–Mn mixed oxides. The combination of the good redox properties of Cu–Mn mixed oxides and gold nanoparticles has proved to be an advantageous approach for developing new catalytic formulations with high effectiveness to eliminate different type pollutants in waste gases from formaldehyde production. The use of high surface area support is beneficial for the stabilization of gold particles in a highly dispersed state and contributes for economic viability in case of practical applications, because of the composition of this catalytic system, that is mostly alumina (80 %).

We report results from an experimental and modeling study of the far-from-equilibrium electrodeposition of Ni–Cu alloys by changing systematically the current density with focus on the surface structuring and surface content of the elements. General finding is that Cu prevails in the convex regions of the deposit, while Ni prevails in the concave ones. No deposition of a monophase is observed by the XRD analyses—in all samples are registered two phases under the form of solid solutions of Cu and Ni. With the increasing current density, the percentage of the major component increases towards deposition of pure Cu and Ni. Some oscillations of the overpotential with the current density are correlated with the Cu content in the Cu-rich solid solution. An original model based on Cellular Automata (CA) rationalizes the hypothesis that during their simultaneous deposition, Cu preserves the diffusion-limited growth mode, while the Ni discharges in a kinetically controlled one. The model is expected to be valid for lower current densities.

In this work, ZnO nanostructures were fabricated on noble-metal (Au, Ag and Au–Ag alloys) coated silicon substrates by applying pulsed laser deposition. The samples were prepared at a substrate temperature of 550 °C, an oxygen pressure of 5 Pa, and a laser fluence of 2 J cm−2 – process parameters usually used for deposition of smooth and dense thin films. The metal layer's role is substantial for the preparation of nanostructures. Heating of the substrate changed the morphology of the metal layer and, subsequently, nanoparticles were formed. The use of different metal particles resulted in different morphologies and properties of the ZnO nanostructures synthesized. The morphology of the ZnO nanostructures was related to the Au–Ag alloy's content of the catalyst layer. It was found that the morphology of the ZnO nanostructures evolved from nanorods to nanobelts as the ratio of Au/Ag in the alloy catalyst was varied. The use of a small quantity of Ag in the Au–Ag catalyst (Au3Ag) layer resulted predominantly in the deposition of ZnO nanorods. A higher Ag content in the catalyst alloy (AuAg2) layer resulted in the growth of a dense structure of ZnO nanobelts.

Nb modified mesoporous SBA-15 and HMS materials were synthesized and studied as a support of NiMo. Calcined co-impregnated NiMo catalysts were prepared using ammonium heptamolybdate and nickel nitrate. Moreover, NiMo catalysts prepared in this manner were treated with thioglycolic acid (TGA). For comparison, NiMo catalysts were prepared by a simultaneous impregnation of the supports with Ni, Mo precursors and TGA. The TGA:Mo molar ratio was 4.0. The supports and NiMo catalysts were characterized by N 2 physisorption, small- and wide-angle XRD, TPD-NH 3 , SEM, UV–vis DRS, FTIR and XPS. Catalyst activity was examined in hydrodesulfurization (HDS) reactions of 1-benzothiophene and thiophene at 350 °C. It was found that simultaneous impregnation by Ni, Mo and TGA led to higher HDS activities than the sequential treatment of the calcined NiMo catalysts by TGA.

The crystal and magnetic structures of the frustrated Co3O4 spinel oxide have been studied by means of neutron diffraction at high pressures up to 8.7 GPa in the temperature range 5–300 K. At ambient pressure, a coexistence of the long range ordered antiferromagnetic (AFM) phase and short range disordered phase below TN = 33 K was observed. At pressures above 2 GPa, a suppression of the magnetically disordered phase and stabilization of the AFM phase, characterized by rapid increase of the Neel temperature in 1.5 times from 33 to 51 K with a pressure coefficient dTN/dP = 2.1 K/GPa occur. The observed phenomena are analyzed in terms of the competing nearest neighbor and next nearest neighbor magnetic interactions. In addition to the A-O-B-O-A nearest neighbor superexchange, an important role of the A-O-O-A next nearest neighbor superexchange interactions in magnetic behavior of Co3O4 is pointed out.

This paper presents a method for fabrication of oriented multicomponent nanowires composed by nanoparticles. The technology is based on nanosecond pulsed laser deposition of mixed target in the presence of an external magnetic field. The targets used for the ablation process consist of Fe2O3 and Ag2O with different ratio between them. The laser ablation is implemented in air at atmospheric pressure by using Nd:YAG laser system operated at 1064 nm. SEM analysis of the surface of the as-deposited samples reveals a presence of micrometric nanowires which are predominantly oriented in the direction of the magnetic field. These nanowires are composed by arranged nanoparticles formed in the plasma plume. The influence is investigated of the Fe2O3/Ag2O ratio in the target on the morphology and optical properties of the structures. Surface plasmon resonance band of Ag nanoparticles was observed in the transmission spectra of the samples with the highest Ag content. The material composition of the samples was identified by EDX and XRD analyzes. The obtained structures can find application in the fields of nanoelectronics, spintronics, magneto-optics and plasmonics.

This paper presents an experimental investigation on laser-assisted fabrication of oriented nanowires composed by magnetic nanoparticles. The nanowires were produced by implementation of pulsed laser deposition in presence of a magnetic field. The application of an external magnetic field led to the formation of nanowires with a length of several micrometers whose orientation is influenced by the direction of the magnetic field lines. The influence of the type of ambient gas and its pressure on morphology and phase composition of the deposited samples was investigated. It was found that the ambient gas has direct influence on both the degree of orientation and the phase composition of the nanowires. SEM analysis of samples deposited at different target-substrate distances showed that the density of the nanowires decreases with the increase of the distance. A preliminary result on the magnetic properties of the produced nanowires is also reported.

Bulk glasses with a composition 20.1Na2O/23.1BaO/23.0TiO2/7.6B2O3/17.4SiO2/3Al2O3/5.8Fe2O3 containing less than 30 mol% glass-forming oxides are synthesized. Information on the valency of the glass constituents is obtained by x-ray photoelectron spectroscopy and it is concluded that all species are predominantly present in their oxidized state. Glassy samples are annealed above the glass transition temperature which leads to the crystallization of BaTiO3 for all time-temperature applied schedules. The phase composition of the glass-ceramics is studied by x-ray diffraction and the formation of cubic BaTiO3 is suggested. Temperature-dependent Raman spectroscopy confirms the presence of solely cubic BaTiO3. The microstructures of all annealed samples are similar and consist of globular interconnected particles in which nanosized BaTiO3 crystals grow randomly. The mean size of the spherical formations increases with the increasing annealing time from 200 to 600 nm. Electron microscopy suggests that during the annealing process first phase separation and then crystallization of BaTiO3 occurs.

Nanosized gold catalysts on Fe-loaded ceria were studied in NO reduction by CO in the presence of H 2 and water. The Fe-modified ceria supports (5, 10 and 20 wt% Fe 2 O 3 ) were synthesized by two different methods: mechanochemical mixing (MM) and impregnation (IM) methods. Gold (3 wt%) was loaded by deposition-precipitation method. The samples was characterized by XRD and H 2 -TPR measurements; Mossbauer spectroscopy results of fresh and used catalysts were used for clarifying the role of Fe addition. It was established that the presence of very small gold particles was not of crucial importance. The Fe-modification of ceria was beneficial for NO conversion, however it decreased the selectivity to N 2 by increasing the selectivity to N 2 O. The 100% selectivity to N 2 at 250 °C as well as a high catalytic activity and stability was observed over gold catalyst on ceria support containing 5 wt% Fe 2 O 3 and prepared by IM method.

NiCo2O4-spinel has been prepared by three different techniques: The Pechini method, a hydrothermal method and a precipitation reaction. The obtained samples have been examined by X-ray diffraction (XRD), differential thermal analysis (DTA) and scanning electron microscopy (SEM). The results reveal that materials prepared by the Pechini method possess two phases (Co3O4 and NiO), those obtained by the hydrothermal method have phases of NixCo3-xO4. Single-phase NiCo2O4 material is obtained only by the precipitation reaction. The obtained NiCo2O4 material is nanosized, exhibiting thermal stability up to 700 °C, where thermal decomposition of NiCo2O4 to Co3O4 and NiO takes place. In the region of thermal stability, a linear thermal expansion of the elementary cell has been observed.

The present work reports on the synthesis of glasses in the system Na2O/Al2O3/BaO/SrO/TiO2/B2O3/SiO2/Fe2O3 from which, after appropriate thermal treatment, barium titanate and strontium-substituted barium titanate glass-ceramics are crystallized. The characteristic temperatures of the glasses are determined by differential scanning calorimetry DSC and show that higher alumina concentrations result in the stabilization of the glass network while an increasing Sr-concentration at constant alumina concentrations leads to a decrease of the glass transition temperature. The phase composition of the prepared materials was analysed by X-ray diffraction and shows precipitations of cubic barium titanate, BaTiO3 and strontium-substituted barium titanate, Ba1-xSrxTiO3. For isothermal treatments and longer annealing times, an additional crystalline phase occurs, i.e. fresnoite (Ba2TiSi2O8). The microstructure investigations of the glass ceramics by scanning electron microscopy witness the occurrence of globular bright crystals enriched in the heavier elements, here Ba, Sr and Ti.

Lithium sodium sulphate (LNS) has been synthesised by two methods: mechanical ball milling and melt quenching. The obtained materials have been studied by means of X-ray diffraction, scanning electron microscopy (SEM), Infrared spectroscopy and differential scanning calorimetry. The influence of the synthesis method on the structure and behaviour of the materials will be discussed.

Transparent organic-inorganic ureasilicate materials (ureasils) were synthesized by hydrolysis and co-condensation of two organic – inorganic precursors, obtained by reactions between 3-isocyanatepropyltriethoxysilane (ICPTES) and double terminated polyetheramine (Jeffamine), and between ICPTES and 3-aminopropyl triethoxysilane (APTES), respectively. The prepared samples were characterized by optical UV – VIS spectroscopy, small-angle X-ray scattering (SAXS), FTIR spectroscopy and the depth sensing indentation method (DSI). It is shown that the molar ratio between the initial components influences on the mechanical and optical properties of the materials in the investigated range.

The synthesis of invert glasses in the system Na2O/TiO2/BaO/Al2O3/B2O3/SiO2/Fe2O3 is reported for different [Na2O]/[Al2O3]-ratios and glass-former concentration less than 30 mol%. During annealing in the glasses cubic and tetragonal BaTiO3 crystals are simultaneously crystallized as proved by X-ray diffraction. Scanning electron microscopy micrographs show that during isothermal heat-treatment globular crystals with sizes from 100 nm to 1 μm are formed. The dielectric properties of the glass-ceramics are studied at room temperature by impedance spectroscopy using two contact points measurement and gold electrodes. The impedance and the phase angle are measured in the frequency range from 0.1 Hz to 1 MHz. The obtained impedance spectra are simulated using an appropriate equivalent circuit in order to extract information on the bulk resistance and capacitance of the sample. Measurements of the capacitance at fixed frequencies are carried out and the dielectric constants are calculated. High dielectric constants in the order of 1000 at a frequency of f = 13 Hz are estimated, which increase with the increasing annealing times and decrease with increasing frequencies.

Glass powders, obtained after vitrification and milling of iron-rich Municipal Solid Waste Bottom Ashes (MSWA), were studied towards manufacture of sintered glass-ceramic material. The crystallization kinetics was investigated both in air and argon atmospheres by non-isothermal Differential Thermal Analysis (DTA). The densification behaviors at different temperatures were studied with optical dilatometry. The formed crystal phases were evaluated with X-ray diffraction (XRD) and the microstructure of samples were observed by scanning electron microscopy (SEM). The investigated composition is characterized with a high crystallization trend and formation of pyroxene solid solutions and melilite solid solutions. Due to additional nucleation process and lower viscosity (because of the lack of Fe2 + oxidation) the phase formation in inert atmosphere is accelerated and is carried out at lower temperature. In the interval 800–900 °C the densification in both atmospheres is inhibited by the intensive phase formation. However, after increasing the sintering temperature up to 1120–1130 °C secondary densification is carried out, resulting in material with zero water absorption, low closed porosity and high crystallinity. Some decreasing of sintering temperature and finer crystal structure are predicted at densification in inert atmosphere.

The aim of our work was to obtain graphene-like phases (graphene oxide and reduced graphene oxide) as fine suspensions by applying pulsed laser ablation to highly purified microcrystalline graphite targets immersed into a water medium. The fundamental wavelength, the second and the fourth harmonic wavelengths of a Nd:YAG laser system (λ = 1064 nm) were used. The morphology of the particles dispersed in water was studied by scanning electron microscopy. Their phase composition and structure were explored by SEM, Raman and XP spectroscopy, GIXRD, as well as TEM. We establish that besides of the main phases of reduced graphene oxide (rGO) with flakes of micro- to nano-sized area and graphite micro-particles, the colloids contain some graphene oxide and defected, multilayered and folded multilayered graphene. The spacing of {0 0 1} increases by about 5–