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A good selection of growth parameters (in-situ etching, C/Si ratio, growth rate) enables obtaining of ~1nm high steps of epitaxial layers, which are comparable to the size of an elementary cell (8°off-axis) and achieve the density of BPD=8•103/cm2. Due to crystallization on substrates with low misorientation (

Polytype instability of SiC epitaxial films was the main focus of attention in the experiment performed since this factor has a decisive influence on graphene growth, which was the second stage of the experiment. Layers deposited in various initial C/Si ratios were analyzed. Our observations indicate that the initial C/Si ratio in epitaxial growth is a crucial parameter determining which polytype will be grown, in particular for cubic (3C) or hexagonal (4H) polytypes. If the initial C/Si ratio was close to its final value, the dominant polytype was 4H. On the other hand, when the initial C/Si ratio was close to zero, 3C became the major polytype in spite of a non favourable growth temperature. The results for graphene growth on an epi-SiC layer and a bulk substrate, in which case the dominant polytype was 4H, are also presented. These results indicate that layers on epitaxial 4H-SiC are thicker, more relaxed and have better quality in comparison with samples on 4H-SiC substrates. Morphology and defects in SiC epilayers were analyzed using Nomarsky optical microscopy, scanning electron microscopy (SEM) and high resolution X-ray diffraction (XRD). Graphene quality was characterized by Raman spectroscopy.

AbstractThe present paper describes an innovative method of producing silver nanoparticles incorporated into an aluminium nano‐oxide substrate. The method utilises thermal decomposition and reduction, which yields an Al2O3–Ag nanopowder with the average size of particles ranging from 43 to 60 nm and the average size of agglomerates between 330 and 870 nm. The average size of the silver nanoparticles incorporated in the aluminium nano‐oxide carrier ranges from 22 to 60 nm. The Al2O3–Ag nanopowders thus produced have a largely developed surface area (above 200 m2 g−1) with a great number of open pores (above 5×10−4 m3 g−1), which gives evidence that their tendency to agglomeration is only slight and that the possible agglomerates have a loose structure. Moreover, the nanopowders show good bactericidal and fungicidal properties. The results obtained in the present experiments show that the Al2O3–Ag nanopowders produced by the proposed method can be used successfully as the raw material in the product...

A consolidation of powders using the KOBO method at elevated temperature was elaborated for production of Al/SiC metal matrix composite (MMC). The observations of the mean strain and inelastic strain range during the force controlled high cycle fatigue (HCF) tests identified the ratcheting mechanism combined with mechanism characterized by cyclic plasticity. Damage parameters were calculated on the basis of strain signal acquisition during fatigue tests. Fatigue properties, creep resistance and lifetime of Al/SiC MMC were gradually improved with the increase of the SiC particles content. The microstructural observations of the material before and after tests were also performed.

Technology of thermal ceramic barriers (TBC) has been chiefly designed for materials with a single thermal barrier of the 7YSZ type. A high content of Y2O3 ensures a good phase stability of the YSZ material. In search for other alternative materials suitable for TBC, the material most often examined is modified zirconium oxide. The modification consists of stabilizing the ZrO2 powder with Y2O3 and doping it with La, Gd and Nd. This paper presents the results of studies on producing cathodic zirconium oxide-based ceramic targets intended for depositing refractory heat-resistant nano-crystalline TBC coatings. The targets are characterized by a high density (close to its theoretical value) and have a homogeneous phase and chemical structure.

The electron backscatter diffraction (EBSD) detector placed inside a commercial scanning electron microscope (SEM) has been used to study of different SiC polytypes. Different growth conditions in chemical vapor deposition (CVD) method were applied to obtain the 3C- and 4H-SiC polytypes epitaxial layers. Growth processes were conducted on the Si-face on-axis 4H-SiC substrates. The growth temperature was in the range of 1300-1620°C and the reactor pressure was 75mbar. The initial C/Si ratio was varied from 0.075 reaching final value of 1.8. It was observed that intentional ramping of the C/Si ratio at the first stage of the growth clearly influences the 4H/3C factor. The growth temperature and ramping of the C/Si ratio were the main parameters to achieve a homogeneous 3C and 4H-SiC epitaxial layers.

This paper summarizes the experimental results in the laser firing of colour agents on ceramic substrates. White glazed and fired ceramic plates were used as the substrate, while the deposited powders were mixtures containing ceramic colours and other colour agents. Various geometric patterns were deposited by a cw fiber Yb:YAG laser with speed controlled by a set of galvanometric scanners. The results, analyzed by means of optical microscopy, SEM EDS and laser profilometry explained the visually observed changes in pattern colours caused by the migration of pigment particles (characteristic elements) and allowed development of proper laser process.

Paper presents a novel application of magnetostrictive delay lines, which give a possibility of real time monitoring of strain in ceramic components. Magnetostrictive delay line was based on highly magnetostrictive Fe-Si-B amorphous alloy ribbon, mounted outside of ceramic component, what is a new solution for increasing sensor’s sensitivity. Developed specially for this sensor, hybrid digital-analog signal processing unit covers the sample-and-hold integrated circuit. The achived sensitivity and repeatability of the sensor confirms, that such solution is suitable for ceramic machine tool monitoring.

Crystallographic quality of the epitaxial layers depends on the process temperature, partial pressures of active components and the surface polarity and also on the crystallographic quality of the subsurface layer resulting from the preparation of the substrate. The polishing etching in hydrogen-propane atmosphere of 4H-SiC substrate of different orientations and polarity was studied. The optimization of the polishing etching has been achieved with respect to the flow of C3H8, the duration and the temperature of the process. The investigation of the surface of SiC substrate before and after in situ polishing-etching in H2+C3H8 atmosphere was carried out by Nomarski interference contrast microscopy (DIC) and atomic force microscope (AFM).

The powder metallurgy (PM) technology was used to produce a porous Co–Cr–Mo-based composite material with the bioactive glass (S2) addition of 5 wt.%, 10 wt.% and 15 wt.%. The results show that the addition of bioglass to the matrix of Co–Cr–Mo alloy, as well as rotary cold repressing and heat treatment of sintered specimens can cause significant changes in the microstructure, mechanical and corrosion properties of composite materials in comparison with the pure porous Co–Cr–Mo alloy. A significant increase in the hardness, yield strength and corrosion resistance of the composites was observed with increasing the bioglass volume fraction. Although all PM samples are in a passive state, the higher corrosion resistances were obtained in the case of the composites with bioglass additions. Superior mechanical properties were achieved in the case of composite with 10 wt.% of bioglass.

The influence of in situ etching of Si-face n-4H-SiC wafers in H2 and propane on the surface morphology of the grown epi-layers were examined using differential interference contrast (DIC) optical microscopy and atomic force microscope (AFM). Two defect-selective etching techniques were applied in order to reveal the type and spatial distribution of defects in the substrates and epi-layers. It was found that for the flow applied in this experiment propane plays a significant role for the etching process. Depending on temperature and etching time we obtained completely different picture of substrate surface morphology. The propane etching was verified as a tool for substrate surface improvement.

GaN and related III–V nitride materials have been applied for fabrication of electronic and optical devices. The most important factor limiting the mass production of devices based on III–V nitride materials is the high cost of substrates and the elaborate growth techniques. The lack of large, bulk GaN substrates causes that the epitaxial layer of nitrides must be grown on heteroepitaxial substrates. The most widely applied are monocrystalline sapphire, SiC and silicon substrates; but the question of cheap and available substrates for nitrides growth is still open. In this paper, authors present some results of the growth of nitrides layer by the metal-organic vapor-phase epitaxy (MOVPE) technique on new nanocrystalline powder substrates (compressed Al 2 O 3 +SiC). The influence of substrate composition (the amount of SiC powder) on the properties of the GaN layer are presented. Also the impact of the conditions of epitaxial process on properties of the nitride layers are discussed.

Microchannels prepared in poly(dimethylsiloxane) (PDMS) structures were coated with a liquid emulsion which was then crosslinked creating a porous layer on walls of the channels. The emulsion contained a PDMS prepolymer mixed with a porogen. In this initial work water was used as a porogen. Having pumped the emulsion through the microchannel, the whole structure was cured at 120 °C in order to crosslink the emulsion and allow to evaporate a porogen. As a result a porous layer on the microchannel's walls was obtained with a so-called open porosity. The evaluation of the porosity was done with the help of numerical analysis. Pores with an equivalent diameter on the order of 4–6 μm were fabricated. Further, fabrication of gas sensor containing a porous layer with a pH indicator is described.

Al2O3/Cr composite ceramic was ion-nitrided in N2 under atmospheric pressure. The plasma was generated by two different systems: an ac high voltage corona discharge, and an ac high voltage concentric dielectric barrier discharge. An analysis of the plasma light emission revealed the presence of N ions (upto 50%) and confirmed the non-isothermal state of the plasma. The treated surface of the high melting sinter was smoothened when its components were nitrided so that Cr is transformed into Cr2N and Al2O3 is transformed into AlN.

The aim of the present study was to examine how the cutting properties of tool blades are affected by super-hard ceramic (carbon) coatings produced by the RF PECVD method. The cutting plates were made of the gradient-type Al2O3/Al2O3 + x%SiCwhiskers composites. The highest density, the greatest bending strength and the highest stress intensity factor were obtained with the layered Al2O3/Al2O3 + x%SiCwhiskers composite. The phase composition of the coatings was examined and the deposited carbon layers were identified to be nanocrystalline diamond (NCD) contaminated with super-finegrained graphite. The thickness, roughness, adhesion to the substrate, friction coefficient and hardness of the coatings were examined. The results evidently show that, when tested in cutting hard aluminium alloys, the carbon coatings deposited on the Al2O3/Al2O3 + x%SiCwhiskers cutting plates by RF PECVD have advantageous cutting properties. The service life of the coated plates compared to that of uncoated plates increased by 65% with the NCD coatings.

The aim of this study was to describe the different aspects of the modification of surface charge of graphene oxide by deposition of Al2O3 nanoparticles on its surface. The novel reduced graphene oxide/Al2O3 nanocomposites were evaluated as an adsorbent for Staphylococcus aureus bacteria cells in electrolyte and drinking water environment. The zeta potential of GO flakes, Al2O3 nanoparticles and RGO/Al2O3 nanocomposite was investigated alone and in the presence of bacteria cells with a special emphasis on the analysis of the zeta potential curves. Our obtained results indicate that the chemical composition of water environment have a significant influence on the electrostatic interactions between sorbent and bacteria. In most cases, the adsorption of bacteria onto adsorbent surface changed its surface charge to similar to adsorbed cells. However, by taking into consideration the sensitiveness and variability of living system such as bacteria cell, we observed that the phenomenon of adsorption (i.e. the physical interactions with sorbent surface) also changed the surface charge of bacteria cells themselves.

Recently, graphene family materials (GFMs) have been introduced among all fields of science and still get numerous attention. Also, the applicability of these materials in many areas makes them very attractive. GFMs have attracted both academic and industrial interest as they can produce a dramatic improvement in materials properties at very low filler content. The aim of this review is to identify, summarize, and present the first available information on the influence of GFMs on soil and water environment as well as identify the knowledge gaps and indicate the directions for the next generation of the original scientific investigations. The paper also presents our first preliminary impact assessment and potential pathways of GFMs distribution in the environment. We used as an example the reduced graphene oxide/Al2O3 nanocomposite (RGO/Al2O3) that has been previously designed and synthesized by us. Authors believe that further work should focus on improvement of characterization methodology applicable for ecotoxicity analyses and possible interactions between GFMs and different living ecosystems. Consequently, the potential impact of graphene and its derivatives on environmental health is a matter of academic interest. However, potential hazards sufficient for risk assessment and concerned with GFMs usage in consumer products first need to be investigated and identified. Further research should focus on gathering knowledge on GFMs properties for life cycle analyses, which still poses a great challenge for scientists.

The gold electrode is functionalized by sequential self-assembly of a monolayer of the title thiolated cyclodextrin with and without dopamine included in the cavities. The structure of α-cyclodextrin modified gold electrode is carefully characterized using STM and AFM. Surface complexation of dopamine is examined and its association constant is evaluated. Chemical reactions accompanying the electrode process of dopamine, which interfere in the electrochemical dopamine determination, are described and the conditions to avoid them are proposed. Dopamine incorporated in the α-cyclodextrin sites anchored to the electrode surface was found to provide electrochemical contact of the electrode with the solution-resident dopamine. Dopamine present in the α-cyclodextrin cavities has different properties compared to dopamine in the bulk buffer solution and can act as a mediator for the dopamine molecules diffusing to the electrode. This unique mediation effect leads to improvement of the sensitivity of dopamine determination using the α-cyclodextrin modified electrode and a procedure for the determination of dopamine in large excess of ascorbate is proposed.

Nanocrystalline BN, AlN, Al 2 O 3 and TiO 2 films were deposited at room temperature onto Si substrates using the Reactive Impulse Plasma Assisted CVD (RIPACVD) method. Some of the so obtained structures were annealed for 1 h at temperatures of 550 and 770K. SIMS investigations of chemical constitution of films showed the presence of the region being the mixture of different atoms, formation of which is typical of processes involving 'ion dynamic mixing' (IDM). The intermixing region did not diffuse away during annealing and had no influence on good dielectric properties of investigated layers that played the role of insulator in MIS structures. So far performed spectroscopic measurements of the dynamics of the structure of plasmoids formed in the course of RIPACVD process show strong anisotropy of ion energy distribution. Namely, in the direction perpendicular to the substrate surface it averages only 0.2 eV, while in the parallel direction (i.e. along the axis of the deposition system) it is approximately 10-15 eV. However, according to the IDM process theory ions with energies E i

Silicon nitride ceramics are promising candidates for engineering and tooling applications because of the excellent combination of their intrinsic mechanical, thermal and chemical properties. To improve the frictional wear resistance and other properties of ceramic tools, their surfaces are modified by the RF sputtering method. The aim of the present study is to modify the surface of the Si 3 N 4 –TiC composites by depositing carbon coatings using the RF sputtering method. The surface roughness, hardness and adhesion of the nanocrystalline NCD layers have been examined. The values of these parameters have been compared to those obtained for uncoated samples. The results indicate that the system is very promising with as regards to both its brittle fracture toughness and machining properties.

Properties of nanocrystalline thin films of selected nitrides are discussed as possible buffer materials for obtaining freestanding GaN wafers. These films are grown by impulse plasma deposition on silicon substrates. We demonstrate high smoothness of these films. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Nano-titania doped with noble metals (Au/TiO2, Ag/TiO2, Pd/TiO2) has been synthesized by mild hydrolysis of the mixture of metal salts or complexes and titanium isopropoxide ((iPr-O)4Ti). After thermal decomposition of the obtained precursors, nanomaterials were formed. Morphological characterization of the nanomaterials was provided by scanning electron microscopy (SEM) and stereological analysis, determining the BET specific surface area, and BJH nanoporosity (pore volume, pore size). It has been found that the structure of nanomaterials (size of nanoparticles and agglomerates) depended strongly on the method of the (iPr-O)4Ti hydrolysis. A minor dependence on the kind of solvents and precursors of noble metals was observed. The presence of doping metal nanoparticles was confirmed by transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX). Nanomaterial phases were identified by X-ray diffraction (XRD). According to the XRD patterns, Ag/TiO2 and Pd/TiO2 products with doping metals in their oxidized form contain Ag-Ti and Pd-Ti phases. Peaks of the metal oxides Ag2O and PdO are absent in the XRD patterns. The average size of TiO2 nanoparticles is situated in the region of 20–60 nm, whereas metals are present as about 10–15 nm sized particles and fine nanoparticles.

This paper is concerned with the synthesis of composites in the Si 3 N 4 –Al 2 O 3 –TiC–Y 2 O 3 system. The materials obtained have a high density and a good fracture toughness (K IC =9.3 MPa√m). Machining tests show that the service life of the tool blades made of these composites may even be tenfold longer than that of commercial blades made of Si 3 N 4 with an additon of Al 2 O 3 , MgO and Y 2 O 3 .

In the present article the assumption has been made that density of ceramics to a significant excent can be controlled by the size distribution function of the powder particles. This assumption has been verified for a series of specimens which were obtained by mixing three alumina powders of different mean size and different diversity in the size of powders particles. A computer program has been developed which helps to select an optimum mixture of the powders assuring a high density of the sintered ceramic. ©

This paper presents results of the experimental investigation on the tensile stress dependence of signal transmission of the magnetostrictive delay line based on amorphous ribbon. These results create possibility of novel application of the magnetostrictive delay lines for real-time monitoring of ceramic components. Such ceramic components are commonly used in machine industry, where real-time tool monitoring is required from the practical point of view. Experimental results presented in the paper indicate that the magnetoelastic wave amplitude decreases with the value of stresses in the rod. This creates possibility of application of the developed methodology for the real-time monitoring of ceramic components in machine industry.

BaTiO3 (BT) nanocrystalline thin films were plasma etched in the course of several experiments which varied in RF power as well as CF4/(CF4 + Ar) gas-mixing ratio. The maximum etch rate of approximately 30 nm/min was observed for the maximum power (300 W) and pure Ar plasma atmosphere, which indicates that the process is controlled by the physical mechanism of Ar ion bombardment, while the increasing content of chemically active plasma component (CF4) in the gas mixture slows down barium titanate etch rate. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Nanocrystalline layers of C3N4, BN, AlN and GaN were grown by Impulse Plasma Assisted Chemical Vapor Deposition method on silicon substrates kept at 300K. Optical absorption studies of the layers revealed broad bands below the fundamental absorption edge, which were ascribed to transitions involving defect levels. When excited by a 3 mW He-Cd laser (325 nm line) all samples showed a wide photoluminescence spectrum (2.0 to 3.5 eV), but the disordered crystalline structure quenched the excitonic photoluminescence observed in monocrystals. The efficient visible luminescence of nanocrystalline AlN layers in the 2–3 eV region observed under non optimal excitation conditions (energy bandgap of AlN is twice the excitation energy) is promising for optoelectronic use of this material as a visible light source.

In this work, results of photoluminescence and absorption measurements on pulse plasma assisted CVD layers of AlN are presented. We studied nanocrystalline layers grown on silicon substrate at a temperature of 300 K. The efficient photoluminescence of nanocrystalline AlN layers, obtained under non optimal conditions, i.e. relatively low excitation energy, seems to be promising for light emitting applications of this material.

In the present article the assumption has been made that the density of ceramics can be controlled to a significant extent by the size distribution function of the powder particles. This assumption has been verified for a series of specimens which were obtained by mixing three alumina powders of different mean sizes and diversity in the size of powder particles. A computer program has been developed which helps to select an optimum mixture of the powders assuring a high density of the sintered ceramic. Samples could be sintered at 1500 °C to a relative density 99.5% and an average grain size of 0.55–0.69 μm. This proves that particle size distribution (p.s.d.) effect on the density of alumina can be utilized in practice of high-density, high-purity ceramics.

Thin (100 nm) nanocrystalline dielectric films of lanthanum doped barium titanate were produced on Si substrates by means of reactive impulse plasma ablation deposition (IPD) from BaTiO 3 + La 2 O 3 (2 wt.%) target. Scanning electron microcopy and atomic force microscopy showed that the obtained layers were dense ceramics of uniform thickness with average roughness R a = 2.045 nm and the average grain size of the order of 15 nm. Measurements of current-voltage (IV) characteristics of metal-insulator-semiconductor (MIS) structures, produced by evaporation of metal (Al) electrodes on top of barium titanate films, allowed to determine that the leakage current density and critical electric field intensity (E BR ) of investigated layers ranged from 10 -12 to 10 -6 A cm -2 and from 0.2 to 0.5 MV cm -1 , respectively. Capacitance-voltage (C-V) measurements of the same structures were performed in accumulation state showing that the dielectric constant value (eri) of films is of the order of 20.

In cooperation with the Institute of Optoelectronics MUT, the Institute of Ceramics and Building Materials conducts work on laser decoration of ceramic products. Two methods are under development: laser activation and laser sintering. The activation method is based on change of color of specially prepared ceramic material due only to illumination by laser beam. Laser sintering is a deposition welding process in which a layer of ceramic powder is deposited on the substrate material, and the two ceramic materials are fused through the application of laser beam, in turn creating any desired color pattern. The paper describes the influence of some physical phenomena on the progress of the laser process as well as sample experimental results.

The present paper provides comparative assessment of antimicrobial efficiency of ionic silver (Ag+), silver monoxide (Ag2O), and metallic silver (Ag) incorporated onto an aluminum oxide nanopowder carrier (Al2O3). The deposition of Ag+ ions, Ag2O nanoparticles, and Ag nanoparticles on an different phases of aluminum oxide nanopowder carrier was realized using consecutive stages of dry sol-gel method. The Al2O3-Ag+, Al2O3-Ag2O, and Al2O3-Ag nanopowders were widely characterized qualitatively and quantitatively by SEM, physical nitrogen sorption and XRD analyses. Results indicate that the Al2O3 nanopowders added with Ag+, Ag2O, and Ag, apart from phase composition, were not differing considerably from one another in terms of their morphology and physical properties. However, nanopowders of Al2O3-Ag were more agglomerated than Al2O3-Ag2O and Al2O3-Ag+ nanopowders. The antibacterial activity of the nanopowders was examined by the spread plate method using bacterial strains such as Escherichia coli, Sarcina lutea, and Bacillus subtilis. The best antibacterial properties against Sarcina lutea strain were achieved in the amorphous-Al2O3-Ag+ and Al2O3-Ag2O nanopowders, whereas the worst antimicrobial activity against Bacillus subtilis and Escherichia coli was shown by the Al2O3-Ag+ and Al2O3-Ag nanopowders. The observed increase of the antibacterial activity as the silver content was not however significant for Al2O3-Ag nanopowders. The results obtained in the present experiments show that the Al2O3-Ag+, Al2O3-Ag2O, and Al2O3-Ag nanopowders, possessing good bactericidal properties, can be produced by using consecutive stages of dry sol-gel method, and Al2O3 nanopowder added with Ag2O is considered as the best raw material in the production of antiseptic materials.

In our previous articles, the crystallization of E-BN, (a high pressure shock wave BN form) from a hydrogen-oxygen flame containing vapours of BH 3 *HN 3 was described. In this work we apply additional flame excitation using a UV photon beam and/or field emitted electrons. The source of the electrons was a corona discharge and of the photons was a UV impulse laser with a power of 5 × 10 4 W. The crystallized materials were identified by transmission electron microscopy (TEM) and X-ray diffraction (XRD). Under the photon and electron activated flames we obtained the high pressure forms of boron nitride (BN), w-BN and E-BN. The w-BN form did not crystallize from the flame without activation. The crystallization results were compared with changes in the flame emission spectra caused by the photon beam and/or the electrons.

Mo contacts of areas varying from 2.4 to 9.4 mm2 were electron beam deposited onto undoped and sulphur doped a-cBN layers. Layers were grown by the reactive pulse plasma method on oxidized, or oxidized and subsequently covered with Au, silicon substrates. Current-voltage measurements of lateral Mo/a-cBN/Mo structures revealed that obtained contacts are non-rectifying high-resistive Schottky contacts: 2 × 105 − 2 × 107 Ω cm2 in the case of doped and 3 × 108 − 1010 Ω cm2 in the case of undoped films. In this article suggestions are also made about possible ways of lowering these resistivities.

Coatings of boron nitride were deposited by spraying a h-BN powder accelerated electrodynamically in a coaxial pulse plasma generator. The coatings were deposited on non-heated silicon substrates, which were, however, heated by the pulse plasma itself. The phase identification performed in this experiment has shown that, under the conditions prevailing during the deposition process, the h-BN powder underwent transformation to form the metastable E-BN phase.

Undoped and sulfur doped amorphous cubic boron nitride (a-cBN) layers were deposited on to silicon substrates by reactive pulse plasma (RPP) method. Subsequently they were annealed at 475, 500 and 700 K for 1 h in pure nitrogen atmosphere. In this study structural and electronic properties of unannealed and annealed layers were investigated. The results show that a consequence of annealing is formation of microstructural stable nanocrystalline cubic boron nitride film as well as substitutional location of introducedin situ donor impurities. This resulted in creation of a-cBN(n-type)-Si(p-type) heterojunction.

In this paper, the electrical properties of a silicon/Sb- doped DLC heterojunction were analysed. The Sb-doped DLC films (DLC:Sb) were obtained by the pulse plasma deposition method. To add Sb3+ dopant, we used SbCl3 evaporation. The results presented indicate that effective doping requires thermal activation. It seems that the simplest explanation of this observation is that Sb atoms, implanted during the film growth process, are located at interstitial positions in a disordered “sparse” layer structure. Only after thermally activated diffusion are they placed in the positions of carbon atoms.

Experiments on BN deposition were carried out using a new electrostatic accelerator with a cascade electrode arrangement. The most interesting result of the experiment is the solid state phase transformation of boron nitride. Particles built of the hexagonal BN phase, which under the present experimental conditions is thermodynamically stable, formed a coating composed of the E-BN phase, which is metastable.

One of the greatest challenges for science nowadays is the protection of the natural environment. Synthetic nanoparticles are released into the environment with industrial and household wastes, and their release can be expected to increase constantly with increasing use of nanoparticles in industry and their increasing share in various consumer products. The penetration of nanoparticles into the water, soil, or air ecosystems may disturb seriously the functioning of the natural environment. In the present study we examined how the active aluminum nano-oxide in the gamma form used as a neutral carrier for the praseodymium (Pr) nanoparticles affected their behavior. Praseodymium is very useful in many branches of science and in everyday life, although in its free form, it is commonly considered to be cyto-toxic, eco-toxic, and phyto-toxic. Our experiments were aimed to find whether the aluminum nano-oxide can act as a nano-stabilizer for the metal nanoparticles, and also to examine whether their bounding on the carrier decreases or eliminates their toxicity to the soil or water microorganisms present in the natural environment. Our experiments have shown that the aluminum nano-oxide is suitable to function as a nano-stabilizer for the Pr nanoparticles. The Al2O3/Pr nanoparticles produced by the dry (conducted in an organic solvent) thermal decomposition of an organic precursor, are not ecotoxic, or less ecotoxic to bacteria isolated from environmental samples, in particular to gram-positive caryopsis of the Micrococcus and Staphylococcus genera isolated from air samples.

Recently, graphene family materials (GFMs) have been introduced among all fields of science and still get numerous attention. Also, the applicability of these materials in many areas makes them very attractive. GFMs have attracted both academic and industrial interest as they can produce a dramatic improvement in materials properties at very low filler content. This article presents recent findings on GFMs toxicity properties based on the most current literature. This article studies the effects of GFMs on bacteria, mammalian cells, animals, and plants. This article also reviews in vitro and in vivo test results as well as potential anticancer activity and toxicity mechanisms of GFMs. The effect of functionalization of graphene on pacifying its strong interactions with cells and associated toxic effects was also analyzed. The authors of the article believe that further work should focus on in vitro and in vivo studies on possible interactions between GFMs and different living systems. Further research should also focus on decreasing GFMs toxicity, which still poses a great challenge for in vivo biomedical applications. Consequently, the potential impact of graphene and its derivatives on humans and environmental health is a matter of academic interest. However, potential hazards sufficient for risk assessment first need to be investigated.

Nanocrystalline c-BN layers obtained by the pulsed plasma deposition method were doped in situ with sulphur vapour. In order to create donor levels, it was necessary that the layers were annealed at a temperature of at least 525 K, either during the deposition process or afterwards. In this way Sip/a-cBNn diodes were produced with a detection coefficient of 104–106 at a voltage of 2 V and photosensitivity to light within the range 0.6 – 1.4 μm.

The aim of the present work was to investigate the in-oxygen-hydrogen-flame synthesis process of BN using a new source of boron and nitrogen, namely the borane-ammonia compound BH3 · NH3, and placing the flame in a strong electric field (6 × 105 V m−1). The metastable form of BN, E-BN, forms as result of an in-flame reaction. The yield of the E-BN synthesis is strongly affected by the presence of the electric field.

In this work we report the recent results of our investigations on synthesis of RE 3+ :Al 2 O 3 nanopowders prepared by a method, in which organic compounds are used as a solvent and lanthanide organic derivatives, and discuss structural and luminescent properties of the powders and PMMA-based composites doped with these powders. The set of the Al 2 O 3 nanopowder samples doped with RE 3+ ions (where RE = Yb and Er) was manufactured and examined with respect of their structural and optical properties. The first PMMA-based composites doped with In this work we report the recent results of our investigations on synthesis of RE 3+ :Al 2 O 3 nanopowders prepared by a method, in which organic compounds are used as a solvent and lanthanide organic derivatives, and discuss structural and luminescent properties of the powders and PMMA-based composites doped with these powders. The set of the Al 2 O 3 nanopowder samples doped with RE 3+ ions (where RE = Yb and Er) was manufactured and examined with respect of their structural and optical properties. The first PMMA-based composites doped with Al 2 O 3 :RE 3+ nanopowders have been manufactured and characterized in the context of their mechanical, structural and luminescent properties. The investigations have confirmed applicability of developed synthesis method to manufacturing of optically active nanopowders of reasonably good structural quality and homogeneity, consisting of nanoparticles with average size in the range of several tens of nanometers as well as possibility of developing the active composite material, based on PMMA polymer host.

In this paper the optical properties of E-BN, a high pressure form of boron nitride, have been investigated. E-BN layers of thickness 1 μm were deposited onto CaF 2 and Al 2 O 3 single-crystal plates by plasma-assisted chemical vapour deposition crystallization using the pulse plasma method. The measured optical properties and calculated value of E g confirm that E-BN is a specific form of BN, differing from c-BN and h-BN.

The paper presents results of an investigation of the electrical properties of cubic boron nitride (c-BN) layers deposited onto silicon substrates by the reactive pulse plasma method. Current-voltage characteristics of the layers in metal/insulator/semiconductor (MIS) structures were investigated in a wide voltage range for films of various thicknesses, obtained under different technological conditions. On the basis of I-V measurements, the breakdown properties of BN layers were also evaluated. In spite of many similarities of c-BN films to diamond-like carbon films, we have found a slightly different character of electrical properties. In most cases we observed switching phenomena and voltage-controlled negative resistance. The dielectric strength of investigated layers shows a wide range of critical electric fields in the range 0.5–6.0 MV cm −1 . An attempt to explain the observed effects on the basis of existing models, valid for similar materials, is also made.

A 16.SG alumina bars were pressed to different densities. Samples of two selected bars were used to create high- or low-density regions at the centre of pressed discs. These discs were sintered by heating to 1600 C. The densities of the discs and each region contained in them were determined before and after sintering. The defects and the microstructure at the interface separating the low- and high-density regions in the sintered specimens were studied using X-radiography and microscopy. Differential sintering was observed in both types of discs. In addition, the presence of a high-density region in a low-density matrix caused radial cracking and a pronounced difference in grain size at the interface.

The rapid development of nanotechnology raises both enthusiasm and anxiety among researchers, which is related to the safety use of the manufactured materials. Thus, the aim of this study was to investigate the effect of aluminium oxide nanoparticles on the viability of selected mammalian cells in vitro. The aluminium oxide nanoparticles were characterised using SEM and BET analyses. Based on Zeta (ζ) potential measurements and particle size distribution, the tested suspensions of aluminium oxide nanoparticles in water and nutrient solutions with or without FBS were classified as unstable. Cell viability, the degree of apoptosis induction and nanoparticles internalization into the cells were assessed after 24 h of cell exposure to Al2O3 nanoparticles. Our results confirm the ability of aluminium oxide nanoparticles to penetrate through the membranes of L929 and BJ cells. Despite this, there was no significant increase in apoptosis or decrease in cell viability observed, suggesting that aluminium oxide nanoparticles in the tested range of concentrations has no cytotoxic effects on the selected mammalian cells.