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The presented paper concerns the technological aspects of the interface evolution in the nickel-silicon carbide composite during the sintering process. The goal of our investigation was to analyse the material changes occurring due to the violent reaction between nickel and silicon carbide at elevated temperatures. The nickel matrix composite with 20 vol pct SiC particles as the reinforcing phase was fabricated by the spark plasma sintering technique. The sintering tests were conducted with variable process conditions (temperature, time, and pressure). It was revealed that the strong interaction between the individual components and the scale of the observed changes depends on the sintering parameters. To identify the microstructural evolution, scanning electron microscopy, energy dispersive spectroscopy, transmission electron microscopy, X-ray diffraction, and Raman spectroscopy were used. The silicon carbide decomposition process progresses with the extension of the sintering time. As the final product of the observed reaction, new phases from the Ni-Si system and free carbon were detected. The step-by-step materials evolution allowed us to reveal the course of the reaction and the creation of the new structure, especially in the reaction zone. The detailed analysis of the SiC decomposition and formation of new components was the main achievement of the presented paper.

The MXene family of two-dimensional transition metal carbides and nitrides already includes ~50 members with distinct numbers of atomic layers, stoichiometric compositions and solid solutions, in-plane or out-of-plane ordering of atoms, and a variety of surface terminations. MXenes have shown properties that make them attractive for applications ranging from energy storage to electronics and medicine. Although this compositional variability allows fine-tuning of the MXene properties, it also creates challenges during the analysis of MXenes because of the presence of multiple light elements (for example, H, C, N, O, and F) in close proximity. Here, we show depth profiling of single particles of MXenes and their parent MAX phases with atomic resolution using ultralow-energy secondary-ion mass spectrometry. We directly detect oxygen in the carbon sublattice, thereby demonstrating the existence of oxycarbide MXenes. We also determine the composition of adjacent surface termination layers and show their interaction with each other. Analysis of the metal sublattice shows that Mo

The present paper investigates the colour dependence of mineral compositions in clay-rich sedimentary strata, mainly clayey silts, the emphasis being on iron-bearing minerals (rather than clay minerals) by using powder X-ray diffraction (PXRD) and 57Fe Mössbauer spectroscopy (57Fe-MS). The PXRD-based phase analysis has demonstrated the variable compositions of samples, consisting of, inter alia, quartz, calcite or gypsum, and admixtures of potassium feldspars and plagioclase. Hematite + goethite (sample D1, dark red), goethite (sample D2, pinkish brown), poorly crystalline goethite (sample D3, orange) and jarosite (sample D4, yellow) have been distinguished. A very low jarosite content was detected in sample D5 (light grey); this did not affect its colour. The potential yellow/brown shades in sample D6 (dark grey), coming from trace amounts of jarosite, are masked by macroscopically visible organic matter. In the case of the two last-named samples (D5 and D6), with trace amounts of Fe-bearing minerals, it is most likely that the organic matter was effective in influencing the light and dark grey colour of the sediment, respectively.

The enhanced performance of superconducting FeSe0.5Te0.5 materials with added micro-sized Pb and Sn particles is presented. A series of Pb- and Sn-added FeSe0.5Te0.5 (FeSe0.5Te0.5 + xPb + ySn; x = y = 0–0.1) bulks are fabricated by the solid-state reaction method and characterized through various measurements. A very small amount of Sn and Pb additions (x = y ≤ 0.02) enhance the transition temperature (Tconset) of pure FeSe0.5Te0.5 by ~1 K, sharpening the superconducting transition and improving the metallic nature in the normal state, whereas larger metal additions (x = y ≥ 0.03) reduce Tconset by broadening the superconducting transition. Microstructural analysis and transport studies suggest that at x = y > 0.02, Pb and Sn additions enhance the impurity phases, reduce the coupling between grains, and suppress the superconducting percolation, leading to a broad transition. FeSe0.5Te0.5 samples with 2 wt% of cometal additions show the best performance with their critical current density, Jc, and the pinning force, Fp, which might be attributable to providing effective flux pinning centres. Our study shows that the inclusion of a relatively small amount of Pb and Sn (x = y ≤ 0.02) works effectively for the enhancement of superconducting properties with an improvement of intergrain connections as well as better phase uniformity.

In this study structural and mechanical properties of a 1 μm thick Al2O3 coating, deposited on 316L stainless steel by Pulsed Laser Deposition (PLD), subjected to high energy ion irradiation were assessed. Mechanical properties of pristine and ion-modified specimens were investigated using the nanoindentation technique. A comprehensive characterization combining Transmission Electron Microscopy and Grazing-Incidence X-ray Diffraction provided deep insight into the structure of the tested material at the nano- and micro-scale. Variation in the local atomic ordering of the irradiated zone at different doses was investigated using a reduced distribution function analysis obtained from electron diffraction data. Findings from nanoindentation measurements revealed a slight reduction in hardness of all irradiated layers. At the same time TEM examination indicated that the irradiated layer remained amorphous over the whole dpa range. No evidence of crystallization, void formation or element segregation was observed up to the highest implanted dose. Reported mechanical and structural findings were critically compared with each other pointing to the conclusion that under given irradiation conditions, over the whole range of doses used, alumina coatings exhibit excellent radiation resistance. Obtained data strongly suggest that investigated material may be considered as a promising candidate for next-generation nuclear reactors, especially LFR-type, where high corrosion protection is one of the highest prerogatives to be met.

Zinc oxide (ZnO) nanostructures exhibiting high exciton binding energy and efficient radiative recombination, even at the room temperature, are of increasing interest due to their prospective exploitation in optoelectronic and laser applications. However, attempts to synthesize well-ordered structures through simple and fast process have faced many difficulties. Here, we demonstrate a novel manufacturing method of ZnO lamellae embedded in a crystalline wide band gap dielectric matrix of the zinc tungstate, ZnWO4. The manufacturing method is based on a directional solidification of a eutectic composite, directly from the melt, resulting in a nanostructured bulk material. Electron microscopy studies revealed clear phase separation between the ZnO and ZnWO4 phases, and cathodoluminescence confirmed exciton emission at room temperature and thus high quality and crystallinity of the ZnO lamellae, without defect emission. Hence, utilization of directional solidification of eutectics may enable cost-efficient manufacturing of bulk nanostructured ZnO composites and their use in optical devices. Graphical abstract

The Ag-Kα and Ag-Kβ fluorescence lines induced by Rh X-ray tube have been observed. The Ag Kβ/Kα intensity ratios for pure Ag and for Ag-Cu alloys have been obtained. The results have been compared with multi-configuration Dirac-Hartree-Fock predictions and available experimental values. Strong dependence between measured Kβ1,3/Kα1,2 and Kβ1,2,3/Kα1,2 ratios and the composition of Ag-Cu alloy has been found out. For both ratios the same tendency is visible: decrease of the Kβ/Kα intensity ratios with increasing of Ag content.

The whitlockite-related materials have attracted researchers' attention because of their potential application in various fields, especially in optoelectronics. In the present work, the structure of novel whitlockite-related oxides Ca

We have performed electron transport and angle-resolved photo-emission spectroscopy (ARPES) measurements on single crystals of transition metal dipnictide TaAs

Intermediate annealing treatment (IAT) is a new process that accelerates the bainitic transformation in steels. This stimulation is crucial, especially in the prolonged production of nanobainitic steels. Among other recognised methods, it seems to be an effective and economical process. However, there are very few research works in this area. The objective of this study was to collate microstructural changes caused by IAT with differences in the kinetics of the subsequent bainitic transformation in the X37CrMoV5-1 tool steel. Differential dilatometry, LM and SEM microscopic observations, EDS and XRD analysis, and computer simulations were used to investigate the effect of IAT on the kinetics of bainitic transformation. The study has revealed that introducing an additional isothermal heating stage immediately after austenitising significantly affects the kinetics of bainitic transformation—it can accelerate or suppress it. The type and strength of the effect depends on the concentration, distribution, and morphology of the precipitations that occurred during IAT.

The MgO-MgAl2O4 eutectic was directionally solidified via micro-pulling down method in the form of rods with 2–3 mm diameter. MgAl2O4 single crystals (with orientation) were used as crystallization seeds. At low pulling rates, especially 0.15 mm/min triangle-like cross-section was observed, which was linked to the eutectic MgAl2O4 following the crystallographic direction of the seed. MgO precipitates in the form of lamellae and rods with median equivalent diameter ranging from 0.19 to 0.85 μm, depending on the pulling rate. The preferred crystallization direction was for both phases, however notable traces of other directions, e.g. , and were found as well.

The application of nano-Ag grains as antiviral and antibacterial materials is widely known since ancient times. The problem is the toxicity of the bulk or big-size grain materials. It is known that nano-sized silver grains affect human and animal cells in some medical treatments. The aim of this study is to investigate the influence of nano-Ag grains embedded in a carbonaceous matrix on cytotoxicity, genotoxicity in fibroblasts, and mutagenicity. The nanocomposite film is composed of silver nanograins embedded in a carbonaceous matrix and it was obtained via the PVD method by deposition from two separated sources of fullerenes and silver acetate powders. This method allows for the preparation of material in the form of a film or powder, in which Ag nanograins are stabilized by a carbon network. The structure and morphology of this material were studied using SEM/EDX, XRD, and Raman spectroscopy. The toxicology studies were performed for various types of the material differing in the size of Ag nanograins. Furthermore, it was found that these properties, such as cell viability, genotoxicity, and mutagenicity, depend on Ag grain size.

We have performed electron transport and ARPES measurements on single crystals of transition metal dipnictide TaAs2 cleaved along the ($\overline{2}$ 0 1) surface which has the lowest cleavage energy. A Fourier transform of the Shubnikov-de Haas oscillations shows four different peaks whose angular dependence was studied with respect to the angle between the magnetic field and the [$\overline{2}$ 0 1] direction. The results indicate the elliptical shape of the Fermi surface cross-sections. Additionally, a mobility spectrum analysis was carried out, which also reveals at least four types of carriers contributing to the conductance (two kinds of electrons and two kinds of holes). ARPES spectra were taken on freshly cleaved ($\overline{2}$ 0 1) surface and it was found that bulk states pockets at the constant energy surface are elliptical, which confirms the magnetotransport angle dependent studies. First-principles calculations support the interpretation of the experimental results. The theoretical calculations better reproduce the ARPES data if the theoretical Fermi level is increased, which is due to a small n-doping of the samples. This shifts the Fermi level closer to the Dirac point, allowing to investigate the physics of the Dirac and Weyl points, making this compound a platform for the investigation of the Dirac and Weyl points in three-dimensional materials., Comment: 12 pages, 13 figures

A unique shield grip decorated with openwork rivet plates was found in a Roman Period cemetery of the Przeworsk culture in Czersk, Central Poland. The artefact underwent specialist analyses with the use of various techniques in order to reveal its silvering technology. Several silvering techniques were considered as the most probable: foil silvering, mercury silvering and silver plating. A number of complementary analytical methods such as laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), scanning electron microscopy with energy-dispersive X-ray (SEM-EDX), X-ray diffraction and neutron techniques were used in the examinations. Two silvering technologies were identified: foil silvering and mechanical treatment of silver pieces. On the basis of the specific correlation of maximum contents of silver (Ag), copper (Cu) and tin (Sn) in external layers of the artefact, it was found out that the surface of the openwork plates had been first covered with alloy with a high content of tin and copper as a solder. Then, a thin silver foil was applied onto it. On the other hand, combs of the shield grip were ornamented using non-soldering technology, i.e. hammering and punching.

In this work, the effect of ion implantation and Cr content on structural properties of ODS steel have been investigated. Structural properties were measured by using Grazing Incidence X-ray Diffraction (GIXRD) and Small Angle Neutron Scattering (SANS) techniques. Mechanical properties, in the function of Cr addition were measured by means of nanoindentation technique. It has been found that bands characteristic for (100), (200) or (211) crystallographic planes, upon impact of ions change their position (shift towards lower 2θ). Implementation of Small-Angle Neutron Scattering (SANS) technique has help to estimate particle characteristics in ODS specimens. Finally, mechanical results clearly show impact of Cr addition on the hardness and Young modulus of the manufactured specimens.

In the presented work 2 at% thulium doped yttrium oxide precursor powders were synthesized by the co-precipitation method using ammonium bicarbonate as a precipitation agent. The main aim of this work was to investigate the influence of co-precipitation parameters such as the process temperature (25°C–70 °C) and molar concentration of reagents on the morphology and luminescence properties of Tm:Y 2 O 3 . The lowest average particle size of about 20 nm and the highest value of the specific surface of 55.2 m 2 /g were obtained for powder co-precipitated at a temperature of 70 °C at a molar concentration of 0.1 M for thulium and yttrium nitrate. The emission spectra of the outcome powders were measured and compared and fluorescence dynamics behavior was presented and discussed.

The magnetocaloric effect in the vicinity of the martensitic transformation for a single crystalline alloy with a composition close to the stoichiometric Ni2MnGa has been determined indirectly by M(T,H) magnetization measurements. It has an inverse character. The magnetocaloric parameters, i.e., the magnetic entropy change, refrigeration capacity and various hysteretic effects have been calculated from the M(T,H) dependences. Besides the martensitic transition a weak entirely separated intermartensitic transition was observed. These two successive magneto-structural transformations give contributions to the observed magnetocaloric effect. Unusual dependence of entropy change as a function of magnetic field has been explained as arising because of two different mechanisms. Additionally, to confirm that studied martensitic transformation is a first order phase transition electrical resistivity and thermoelectric power measurements have been performed.

Electron paramagnetic resonance was used to investigate Mn impurity in Bi 2 Se 3 topological insulator grown by the vertical Bridgman method. Mn in high-spin S =5/2, Mn 2+ , configuration was detected regardless of the conductivity type of the host material. This means that Mn 2+ (d 5 ) energy level is located within the valence band, and Mn 1+ (d 6 ) energy level is outside the energy gap of Bi 2 Se 3 . The electron paramagnetic resonance spectrum of Mn 2+ in Bi 2 Se 3 is characterized by the isotropic g-factor | g |=1.91 and large axial parameter D =−4.20 GHz h. This corresponds to the zero-field splitting of the Kramers doublets equal to 8.4 GHz h and 16.8 GHz h, respectively, which is comparable to the Zeeman splitting for the X-band. Mn in Bi 2 Se 3 acts as an acceptor, effectively reducing native-high electron concentration, compensating selenium vacancies, and resulting in p-type conductivity. However, Mn-doping simultaneously favors formation of native donor defects, most probably selenium vacancies. For high Mn-doping it may lead to the resultant n-type conductivity related with strong non-stoichiometry and degradation of the crystal structure - switching from Bi 2 Se 3 to BiSe phase.

Although zinc oxide has been widely investigated for many important applications such as laser diodes, photovoltaics, and sensors, some basic properties of this material have not been established up to now. One of these are stopping power values which are crucial for the Rutherford Backscattering Spectrometry analysis. For this kind of measurements, amorphous materials should be used. In this paper we show the results of stopping power measurements for ZnO films grown by Atomic Layer Deposition. The films were grown on a silicon (100) substrate and parameters of the growth were chosen in a way that prevents crystallization of ZnO films. A series of ZnO films with thickness between 20 and 160 nm have been investigated. Extended film characterization has proven that the obtained nanopolycrystalline ZnO films can be considered as truly amorphous with respect to ion beam applications. ZnO films have been used for precise stopping power measurement of MeV He-ions in the energy range from 200 to 5000 keV. These results provide indispensable data for ion beam modification and analysis of ZnO.

A microstructured manganese titanate – titanium dioxide, MnTiO 3 –TiO 2 , hybrid eutectic has been grown by the micro-pulling-down method from a TiO 2 57 mol.% – MnO 43 mol.% composition. X-ray powder diffraction verifies that two phases have been formed: rhombohedral MnTiO 3 and tetragonal TiO 2 . The TiO 2 phase forms a three-dimensional network of micron-scale oval precipitates interconnected with c.a. 0.5 μm in thickness lamellas and the MnTiO 3 is the matrix phase. The two TiO 2 precipitate types grow in different crystallographic orientations, which results in this complex geometry made of faceted and non-faceted inclusions. The lamellas grow in the [010] orientation in which a 2-fold axis is present, while the oval precipitates grow in the [001] orientation in which the 4-fold screw axis is present. A qualitative and quantitative analysis of the eutectic microstructure is presented. The MnTiO 3 –TiO 2 composite is interesting due to its potential application in photoelectrochemistry.

The results of studies on preparation of gadolinium zirconate pyrochlore ceramics are presented. Gd 2 Zr 2 O 7 powders were prepared by repeated annealing and milling runs of commercial ZrO 2 and Gd 2 O 3 micro- and nanopowders and hot-pressed at 1450 °C. Scanning Electron Microscopy (SEM) analysis of the microstructure shows average grain size to vary from 1.0 to 5.9 µm depending on a type of used mixtures. Sintered ceramics were characterized by X-ray diffraction. The highest intensity of the pyrochlore superstructure peaks was found for ceramics obtained from the mixture of nanopowders. The ratio of intensity of the strongest pyrochlore line to the intensity of the strongest peak characteristic for both structures (fluorite and pyrochlore) equals to 4.5% indicating about 80% pyrochlore ordering.

Second-order nonlinear optical materials are used to generate new frequencies by exploiting second-harmonic generation (SHG), a phenomenon where a nonlinear material generates light at double the optical frequency of the input beam. Maximum SHG is achieved when the pump and the generated waves are in phase, for example through birefringence in uniaxial crystals. However, applying these materials usually requires a complicated cutting procedure to yield a crystal with a particular orientation. Here we demonstrate the first example of phase matching under the normal incidence of SHG in a biaxial monoclinic single crystal of zinc tungstate. The crystal was grown by the micro-pulling-down method with the (102) plane perpendicular to the growth direction. Additionally, at the same time white light was generated as a result of stimulated Raman scattering and multiphoton luminescence induced by higher-order effects such as three-photon luminescence enhanced by cascaded third-harmonic generation. The annealed crystal offers SHG intensities approximately four times larger than the as grown one; optimized growth and annealing conditions may lead to much higher SHG intensities.

MgAl 2 O 4 (MALO) single crystals were pulled by the Czochralski method in [111] direction. The crystalswere doped with Co (0.06–0.6 at% (charge compositions)), because Co 2þ ions in tetrahedral positionsexhibit non-linear optical properties, and, currently, Co:MALO seems to be the best saturable absorber inthe eye-safe region (ca. 1.5 mm). By XRD powder technique a stoichiometric MALO was evidencedwithout admixtures of higher order spinels (MgAl 4 O 7 and MgAl 6 O 10 ). Also no excessive residual stresseshave been discovered by different optical methods, and irrespective of the doping level we did not faceany problem of cracking when cutting the crystals into wafers and other structures. In this work we haveconcentrated our efforts on investigation of thermal properties of MALO. Due to the 2nd order phasetransition ca. 650 1C they seem to be of crucial importance in future thermal bonding of this material tothe lasing host (Yb,Er-glass) expected just about this temperature.& 2013 Elsevier B.V. All rights reserved.

In this paper we present the results of the investigations of nanostructured C-Pd films for hydrogen sensing applications. These C-Pd films were prepared by physical vapor deposition and then annealed in an argon flow at the temperature of 500°C. The structure and morphology of the prepared C-Pd films were investigated using transmission electron microscopy and energy dispersive X-ray spectroscopy. We studied the infiuence of hydrogen on the electrical properties and crystal structure of C-Pd films. It was shown that film resistance changes depended on hydrogen concentration. At lower hydrogen concentration (up to 2 vol.%), the films response increased proportionally to [H2], while above 2 vol.% H2, it was almost constant. This is connected with the formation of a solid solution of hydrogen in palladium at lower H2 concentration and the creation of palladium hydride at higher H2 concentration. X-ray diffraction was used to confirm the formation of Pd-H solid solution and palladium hydride.

We propose nanostructured carbonaceous-palladium (C–Pd) films as promising material for covering different, big surfaces as improving hydrogen storing properties material. The C–Pd films were obtained by annealing of samples prepared by physical vapor deposition on fused silica substrates. Palladium nanocrystallites placed within the film volume and also on its surface enhanced absorption of hydrogen due to dissolution of H 2 molecules in the nanocrystallites. We studied structure, morphology and topography of these films by different methods (XRD, GIXRD, SEM and EDS). XRD measurements performed in situ under H 2 /N 2 atmosphere showed that α phase and β phase of palladium hydride were formed.

In this paper we present new nanocomposite materials ability to use in hydrogen sensing applications. Nanocomposite films were obtained by several techniques such as PVD, PVD/CVD (physical vapor deposition/chemical vapor deposition) methods as well as by annealing of films prepared by PVD process. The films are composed of Pd nanograins embedded in the carbonaceous matrix. These Pd nanograins are responsible for palladium hydride PdH x formation. Creation of PdH x in these films was observed during in situ GIXD (graizing incidence X-ray diffraction) measurements. The hydrogen sensing characteristics by dc electrical measurements were also shown. We discuss how the structure of Pd-C films, palladium nanograins and the carbon matrix affect the sensing properties in terms of response time, sensitivity and reversibility.

The ability of gadolinium zirconate pyrochlore for actinides incorporation in its lattice makes this material a possible matrix for the immobilization of nuclear wastes. The aim of the presented work was to develop a novel method of gadolinium zirconate synthesis by using a reactive sintering procedure under high pressure based on commercial ZrO2 and Gd2O3 nanopowders. Samples were analyzed using X-ray diffraction and SEM to check their phase composition and microstructure. The obtained sintered pellets demonstrated peaks characteristic for pyrochlore structure for a wide range of preparation temperatures and high density (99.5 % of the theoretical value). It was found that the resulting materials exhibited a homogeneous microstructure and the average grain size dependent on sintering temperature.

The effect of the presence of CeO2 in the source material on the properties of SiC crystals grown by Physical Vapor Transport (PVT) method is investigated. The doping efficiency and, indirectly, the presence of the cerium vapour in the growth atmosphere were examined by study of structural, electrical and optical properties of the crystals. X-ray photoelectron spectroscopy shows that Ce2O3 and CeO2 coexist on the SiC post-growth surfaces. A detectable Ce incorporation is observed only in the last grown part of the crystal.

In this work results of nitrogen doping in the amount of 0 vol.%, 3 vol.% and 10 vol.% on the growth of the 4H polytype on the 6H-SiC seed are presented. SiC crystals grown by PVT method on the (000-1) C-face of 6H seeds using the open seed backside design have been investigated. Structural and electrical properties of the crystals were studied by different experimental methods.

Eutectic materials have potential as photoactive materials, due to their multiphase character (various available photoactive component phases and multiple band gap energies) and high crystallinity....

The use of lithium manganese oxides in rechargeable lithium ion batteries has been stimulated due to their low cost and environmental compatibility. Especially, the interest of scientists concerns the oxide of the stable, spinel structured LiMn2O4. In the present work, this compound has been synthesized by three different methods viz., solid state reaction, modified sol–gel, and microwave hydrothermal techniques. The phase compositions of products were investigated by X-ray powder diffraction (XRD) method and the surface morphology of nanopowders was examined by the scanning electron microscopy (SEM) (© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Nanocrystalline lithium–manganese oxide spinels were synthesized by a modified sol-gel method. Simple salts of lithium, manganese and iron were used as starting reagents and citric acid as a complexing agent. The gelled materials turned into nanopowders after the calcination was carried out in air in the 450–700 °C temperature range. The combined DSC-TGA measurements have shown important stages of the syntheses. They also enabled to find optimum calcination temperatures. Microstructure of all synthesized materials, as investigated by SEM, contains relatively large grains (over 100 nm), which are agglomerates of much smaller crystallites. X-ray diffraction (XRD) has shown that the final powders are single-phased, with a lattice parameter a varying from 8.16 to 8.25 A, depending on the material. The average crystallite size, as estimated from broadening of XRD reflections by a Scherrer formula, is about 30 nm. Electrical conductivity depends on temperature according to an Arrhenius equation with the activation energy of 0.30 eV.

Crystals of PrxLa1−xAlO3 solid solution have been grown by the Czochralski method for the first time, to the best of our knowledge. Crystals with high praseodymium concentration tend to grow spirally. The color of the crystals changes with chemical composition. X-ray diffraction shows an increase of the lattice constants with an increase in lanthanum ion concentration. The thermal conductivity has been investigated in the temperature range from 5 to 300 K. Completely different behavior of thermal conductivity is observed at low temperatures for the investigated crystals, whereas it remains roughly constant at high temperatures. The values of magnetic susceptibility lie within the expected range that could be expected for a paramagnetic material.

In this work we present the growth of 4H-SiC crystals (2 inch in diameter) on the 8° off- axis C-face 6H-SiC seeds, inclined toward [11-20] direction. The growth of crystals by physical vapour transport method (PVT) was realized with the open seed backside in the experimental setup with graphite resistive heater. Some of the crystals were doped with cerium in the purpose of the 4H polytype growth stabilization. For Ce-doped crystals the seed backside carbonization process was decreased in comparison with such effect observed in the undoped SiC crystals.

Results of vanadium doping in PVT SiC bulk growth by the use of the seeding technique with an open seed backside are shown. Structural and electrical properties of 4H and 6H-SiC:V were investigated by a variety of experimental methods. In the crystal studied, the solubility limit of V in SiC was exceeded and structural defects consisting of V-rich precipitates occured. Electrical properties of this crystal were determined by the V3+/V4+ acceptor level. The V3+ charge state of vanadium was formed by compensating shallow donors (mainly nitrogen) and for both 4H and 6H polytypes it was detectable in optical absorption (in the near-IR range) and electron paramagnetic resonance.

Metamaterials offer new unusual electromagnetic properties, which have already been demonstrated, and many postulated new functionalities are yet to be realized. Currently, however, metamaterials are mostly limited by narrow band behavior, high losses, and limitation in making genuinely 3D materials. In order to overcome these problems an overlap between metamaterial concepts and materials science is necessary. Engineered self-organization is presented as a future approach to metamaterial manufacturing. Using directional solidification of eutectics, the first experimental realization of self-organized particles with a split-ring resonator-like cross section is demonstrated. This unusual morphology/microstructure of the eutectic composite has a fractal character. With the use of TEM and XRD the clear influence of the atomic crystal arrangement on the microstructure geometry is presented. The materials obtained present very high anisotropy and can be obtained in large pieces. Metallodielectric structures can be created by etching and filling the space with metal. The next steps in the development of self-organized materials exhibiting unusual properties are discussed.

X-ray absorption fine structure (XAFS) studies of Ni nanograins embedded in carbonaceous films were performed basing on the K edge spectra of nickel. A series of samples containing various doses of Ni doped to the film during the deposition was studied. The crystalline structure and chemical constitution of formed nanograins were found dependent on the nickel dose. They change along the series from those similar to bulk structure of metallic Ni towards amorphous form of NiO. The Fourier transform fitting analysis based on Ni fcc and NiO rock salt models showed for all samples a significant reduction of the range of atomic order around Ni as compared to appropriate bulk materials. The changes in an oxide content rate in the nanograins were evaluated by fitting the coefficients of the linear combination spanned on two the most distinct measured XAFS spectra. We have found that low oxygen inflow resulted in formation of amorphous NiO, but saved the metallic core of grains. High oxygen uptake resulted in thorough grain oxidation.

4H-SiC single crystals grown by the seeded physical vapour transport method have been investigated. These crystals were grown on 6H-SiC seeds. The influence of the seed temperature, form and granulation of SiC source materials on the stability and efficiency of the 4H polytype growth have been investigated. A new way of the seed mounting - with an open backside - has been used. Crystals obtained were free of structural defects in the form of hexagonal voids. The crystalline structure of SiC crystals was investigated by EBSD (Electron Backscatter Diffraction) and X-Ray diffraction methods. Moreover, defects in crystals and wafers cut from these crystals were examined by optical, scanning electron and atomic force microscopy combined with KOH etching.