Search

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.

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.

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 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.

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.

The praseodymium aluminum perovskite−praseodymium hexaluminate (PrAlO3−PrAl11O18) eutectic has been studied for the first time. It has been grown by the micro-pulling down method from a composition...

The praseodymium-aluminum perovskite−praseodymium oxide, PrAlO3−Pr2O3, eutectic has been studied. The growth of the eutectic by the micro-pulling down method is presented. The PrAlO3−Pr2O3 is not air-stable. The cause of the eutectic instability is the instability of the Pr2O3 phase. When exposed to air, the Pr2O3 phase changes into a new compound having a hexagonal unit cell with the lattice parameters a = b = 6.455(1) A, c = 11.322(4) A. The PrAlO3−Pr2O3 eutectic grows with a regular complex microstructure. The luminescence spectra are presented for both the eutectic and the new phase generated by exposing the eutectic to air.

Two components of electronic wastes (sample A – a mixture of three types of printed circuit boards, sample B – a mixture of electronic junctions with metal wires) were investigated using thermogravimetric analysis (TG). Thermogravimetric and derivative thermogravimetric data (TG and DTG) give information on the thermal stability of A and B samples and allows finding the correct conditions for their degradation using pyrolysis in an experimental system, built on the laboratory scale for utilization of hazardous wastes. X-ray fluorescence measurements prove that brominated flame retardant is present in sample A, whilst chlorinated flame retardant is a probable component of sample B. Preliminary liquid chromatography of oil products obtained as a result of thermal waste degradation shows that the hydrocarbons released during pyrolysis could be used as a fuel.

Shot peening is commonly used to modify material surface layers and improve the strength of metal components. As it occurred the same technique can be applied for brittle ceramics. High compressive stresses up to 2.4 GPa were introduced into near surface region of alumina and zirconia ceramics by ultrasonic shot peening maintaining its surface integrity. Dependence between diameter of tungsten balls, treatment time (at constant mass of balls in the housing and vibration amplitude) and level of compressive stress introduced was determined for both ceramics with nano and micrograins. Coarser grained ceramics was found to be more sensible to structural changes responsible for stress creation than the smaller one. High microplastic deformation in shot peened surface layer of ceramics was observed by X-ray diffraction. An increase of hardness and surface resistance to fracture with increasing level of compressive stress was found.

An ultra-fine grained microstructure was obtained in high purity nickel by a combination of (a) equal-channel angular pressing (ECAP) and (b) hydrostatic extrusion (HE) with a cumulative true strain of ~11.2. The resulting microstructure was examined by light and TEM microscopy. Mechanical properties have been measured by tensile and hardness tests. It was found that HE of ECAP-ed samples leads to a significant grain size refinement (from 330 to 160nm) and to an increase in microstructural homogeneity. SPD nickel, made by a combination of the ECAP and hydrostatic extrusion methods, has high strength and ductility (i.e.: YS=1120MPa and εf = 11%). The microstructure transformation was accompanied by a strength increase of 78% compared to ECAP alone. The results obtained fit well with the Hall-Petch relationship. A combination of ECAP and HE has achieved much better properties than either single process and show it to be a promising procedure for manufacturing bulk UFG nickel.

Praseodymium-aluminum (PrAlO3) perovskite crystals have been grown by the Czochralski method for the first time, to our knowledge. An almost periodic microtwin structure has been observed in the as-grown crystals, and a three-dimensional texturing of the polished surfaces has been observed. Optical absorption and emission spectra have been investigated at room temperature for crystals containing only Pr3+ ions as well as for crystals containing a mixture of Pr3+/Pr4+ ions. The observed broad emission band for the as-grown crystals could lead to a future potential application as a tunable laser for the whole visible range.

Modification of material surface layers by conventional shot peening is commonly used to improve the strength of metal components. As it occurred high compressive stresses up to 2.0 GPa may be introduced also to near surface region of alumina ceramics by this technique. Two alumina ceramics were given to ultrasonic shot peening which is a new, compact and small consuming of shot media method developed by Sonats company. This process is named Stressonic®. The dependence between diameter of tungsten balls, treatment time (at constant mass of balls in the housing and vibration amplitude) and level of compressive stresses introduced was determined. High microplastic deformation in shot peened surface layer of alumina was observed by X-ray diffraction. An increase of surface resistance to fracture of ceramics with increasing level of compressive stresses was also found.

We describe the synthesis and characterization of aligned carbon nanotubes deposited on quartz substrates by pyrolysis of a xylene–ferrocene mixture at 700 °C at atmospheric pressure. For microscopic characterization of the pyrolyzed products, scanning and transmission electron microscopies and scanning tunneling microcopy were used, and properties of bulk samples were characterized by Raman spectroscopy and x-ray powder diffraction methods. The nanotubes have topological defects and many contain metal particles. Scanning tunneling spectroscopy proved that the nanotubes had a metallic electrical conductivity with resonant states near the Fermi energy. The states are ascribed to the dangling bonds originating from the defects.

C60/C70: Ni films with 1.5 wt. % Ni concentration obtained by vacuum deposition under different thermal conditions have been investigated. The structural changes of the layers were investigated by transmission electron microscopy, electron and x-ray diffraction, and Raman spectroscopy. The polycrystalline structure was detected for the layers grown at approximately 450 K on the substrate. At elevated temperature and maintained temperature gradient on the substrate during the process, the changes of the layer's structure and the formation of Ni microcrystals were observed. The Ni microcrystals (5–10 nm in the diameter) and the elongated shapes dimensioned 10 × 150 nm were perceived.

The effect of thermal treatment of a typical active carbon at 1300 °C and 1900 °C on its structural properties was investigated. It has been found that only a high-temperature heating (1900 °C) produced substantial changes in the structure of the carbon used: a disappearance of a considerable part of open micropores and formation of a turbostratic structure. The prepared materials were used as a support in catalysts for NH3 synthesis. The precursor of the active phase was Fe(NO3)3 · 9H2O. The iron nitrate deposited on the raw amorphous carbon decomposes to finely dispersed, hardly reducible iron oxides on heating to 470 °C in a H2 + N2 mixture. Even if reduced to more than 33%, iron is inactive in NH3 synthesis (400–470 °C, p = 10MPa). When deposited on the turbostratic, low-surface area carbon, iron forms, however, well developed crystallites (~60 nm), and is active in ammonia synthesis. Potassium activates strongly the surface of Fe, and, in the case of the amorphous support, it stimulates the reduction of iron oxides.

The carbon deposits on graphite electrodes formed during the electric discharge in a chamber used for fuUerene production contained nanotubules and fullerenes. X-ray and high resolution transmission electron microscopy investigation revealed that the deposits consisted of strongly deformed graphite microblocks. The nanotubules were found at boundaries of microblocks where carbon hexagonal planes were strongly distorted, suggesting that nanotubules were formed during atomic carbon condensation.

Yb-doped Sr3Y(BO3)3 nanocrystallites incorporated into polymethyl methacrylate matrices (4.5% by weight) were optically treated by coherent picosecond laser pulses at 1.34 and 0.67μm. This composite exhibits a large effective electro-optic coefficient (up to 6.2pm∕V at 1040nm wavelength). Decrease of the nanocrystallite size and increase of the Yb content lead to substantial enhancement of the effective electro-optic coefficient. For nanocrystallite sizes equal to about 5nm, the coefficient increases from 2.2pm∕V (8% of Yb) up to 6.2pm∕V (20% of Yb). This material appears thus promising in application for the optically operated modulators.Yb-doped Sr3Y(BO3)3 nanocrystallites incorporated into polymethyl methacrylate matrices (4.5% by weight) were optically treated by coherent picosecond laser pulses at 1.34 and 0.67μm. This composite exhibits a large effective electro-optic coefficient (up to 6.2pm∕V at 1040nm wavelength). Decrease of the nanocrystallite size and increase of the Yb content lead to substantial enhancement of the effective electro-optic coefficient. For nanocrystallite sizes equal to about 5nm, the coefficient increases from 2.2pm∕V (8% of Yb) up to 6.2pm∕V (20% of Yb). This material appears thus promising in application for the optically operated modulators.

The gadolinium ferrochromite (GdFe1−xCrxO3) was used as a case study of influence of chromium substitution on the perovskite structure in the entire composition range. By exploiting thermal analysis techniques (dilatometry, differential thermal analysis) the influence of chromium was investigated in the context of thermal stability of the canted antiferromagnetic ordering. It was found that the higher the chromium concentration was, the more the Neel temperature decreased, e.g., substitution of 26 % of iron atoms corresponded to a depression of about 60 K with respect to undoped gadolinium ferrite. For higher chromium concentrations the mixed gadolinium ferrochromite was paramagnetic at room temperature. Additional information on the crystal structure and, qualitatively, on the magnetic ordering as well was derived from the results of X-ray diffraction and Mossbauer spectroscopy measurements. For chromium content higher than 10 % the gadolinium ferrochromite may be regarded as a solid solution. For lower concentrations, however, a possible formation of clusters with different Fe/Cr ratio occurs as suggested by Mossbauer spectra.

A unique relief fibula dated to the Migration Period (first half of the sixth century) was found in Radziejow, Poland. This stray find changes previous opinions on the lack of settlement in central Poland at that time. As the find is the only one of such type in Poland, a special attention was paid to possible analogies, mainly finds from Scandinavia and Western Europe. The fibula underwent technological analyses in order to reveal its technology of manufacture. For this purpose, the chemical and elemental composition of the alloy was studied. Several physico-chemical complementary techniques such as optical microscopy (OM), scanning electron microscopy with energy dispersive X-ray (SEM–EDX) spectroscopy, energy dispersive X-ray fluorescence (ED-XRF) analysis, X-ray diffraction (XRD) analysis and micro-hardness testing (HV0.2) were used to study the technology of the find. The investigations revealed that this artefact was made from brass (4–17 wt% Zn) with an admixture of Sn (2–12 wt%). Two technologies were used: casting for the bow and forming for the part with the axle of the spring. The artefact’s surface was tinned in the hot-dipping process. The physical structural analyses demonstrated that the artefact was cast and ornamented by surface stamping under a relatively low temperature (about 500 °C).