In polar semiconductor samples of the self-organized quantum dots, grown by the Stranski-Krastanow growth method, the lowest-energy extended states of the motion of the electronic excitations, are assumed to be the wetting-layer states. The coupling between these extended states and the electronic states localized in the individual quantum dots, may influence the optical spectra of such samples in the sub-wetting layer region of energy. This effect is studied assuming the Fröhlich's coupling between the electrons and the polar optical phonons. The contribution of this interaction to the appearance of the sub-wetting layer continuum in the optical spectra, and to the level broadening of the localized states, pointed out in some experiments, is estimated.

The purpose of the design, construction and implementation of vacuum apparatus for measuring simultaneously three or more stimulated phenomena in dielectrics and eventually semiconductors is to investigate those phenomena as a function of temperature and wavelength. The test of equipment and its functionality were carried out step by step (apparatus, components and control sample) and associated with the calculation of the main physical parameters. The tests of individual parts of the apparatus clearly confirmed that the design, construction and selected components fulfil or even exceed the required properties. On the basis of the measurement of selected sample, it was shown that even weak signals from the material can be detected from both thermally stimulated luminescence and thermally stimulated exo-electron emission moreover transmission and desorption can be measured. NaCl:Ni (0.2%) was chosen as the test material. The activation energies and frequency factor were calculated using the methods of different authors.

Cubic perovskite SrTi1-xMnxO3 nanopowders with x = 0-0.5, which is much higher than the conventionally believed Mn incorporation limit, and particles sizes 10-80 nm have been successfully synthesized using the citrate sol-gel method. The crystalline structure, the morphology, the chemical composition and the lattice constant behavior versus the annealing temperature and the Mn concentration have been characterized using X-ray diffraction, scanning electron microscopy and proton-induced X-ray emission techniques. Studies of Raman light scattering and the magnetic properties revealed the activation of the TO2 polar mode and the magnetic ordering effects at low temperatures. Such features are treated as possible evidence of non-d(0) Mn-driven transition to a polar phase with multiferroicity in heavily concentrated perovskite SrTi1-xMnxO3 nanopowders. (C) 2013 Elsevier B.V. All rights reserved.

A set of KTaO3 nanopowders has been prepared at T=180°C using various aliphatic alcohols and water as solvents. Pronounced connection between the solvent type and potassium tantalate structures was found. Structural X-ray, TEM and Raman scattering experiments have shown that the solvent dielectric constant ɛ is an important critical parameter. At ɛ∼24 the cubic perovskite-type phase was formed. Mixed perovskite and pyrochlore phases were formed at larger values of ɛ. Only pure pyrochlore phase is realized when ɛ∼80. Pyrochlore-free perovskite-structure nanopowder phase formation with the particle size of ∼18 and 28nm was achieved when ethanol and isopropanol solvents were used. Under annealing the coherent domain size decreased down to 6 and 18nm respectively, since the amorphous phase crystallized. Crystallinity of both as-prepared and annealed powder is the best when isopropanol solvent is used.

The main goal of the research is to study gradients of stresses and hardness in surface layer after shot peening and to look for correlations between these quantities, and this way to contribute to understanding of the onset of residual stress formation in engineering materials. X-ray diffraction was applied as a main technique for microscopic and macroscopic residual stress determination. Combination of X-ray diffraction with electrolytic polishing enables to study the depth profile of aforesaid quantities. Indentation on polished cross sections was used to study hardness depth profiles. It could be state that the shot peening produce the compressive macrostresses and the depth of the compressive layer is primarily influenced by intensity of blasting.

Impacts of microscopic and macroscopic residual stresses on X-ray diffraction profiles are briefly reviewed. Depth distributions of residual stresses in a shot-peened steel sample obtained by Xray diffraction are presented. Abstrakt Příspěvek popisuje vliv mikroskopických a makroskopických napětí na profily rentgenových difrakčních linií. Jsou uvedeny hloubkové průběhy zbytkových napětí v balotinované oceli, které byly získány pomocí rentgenové difrakce.

An analogy between diffraction profiles and probability distributions of random variables is a basis for the utilization of the mathematical formalism of the theory of probability in the line profile analysis. Namely, the first and the second moments were used to the describing of a position and a breadth of diffraction profiles. Higher moments were introduced also in the line profile analysis, especially the fourth moments for the estimation of the particle size and the microstrain from a single line. However, the formulas for these higher moments are more complicated. Besides the moments, cumulants of random variables were introduced in the theory of probability. The purpose of the contribution is to show, that the cumulants can be used very advantageously in the line profile analysis, especially instead of the higher moments of the diffraction profiles and in the case when number of convoluted functions is a higher as two.

The gradients of the real structure parameters (stress, particle size, textures, etc.) are present in surface of steels or another material after surface machining, e.g., grinding, shot-peening, burnishing. To study these gradients, X-ray diffraction measurements under various conditions, i.e., radiations, tilt angles Psi, diffraction angles 20, can be useful. The aim of the contribution is to discuss the effect of penetration of the used radiation into a matter and depth averaging of parameters of the real structure, The radiations CUKa COKa Cr-Ka most frequently used in laboratory conditions, have been considered in the present study.

Titanium–carbide films were grown using a magnetron assisted pulse laser deposition combining KrF pulsed laser deposition and DC magnetron sputtering (PLDMS). Plasma streams produced by magnetron and laser ablation were intersected on the substrate surface. Films' properties were characterized by GDOES, AFM, XRD, XPS as well as by Raman spectroscopy. The adhesion and microhardness were also studied. Crystalline TiC films were fabricated at room temperature.

The problem of deconvolution is common to many branches of science, technology, medicine, etc. It always occurs when it is necessary to remove an instrumental distortion from a measured signal. The deconvolution belongs to the category of inverse problems which are often ill-posed, incorrect - the existence, unambiguity and stability of the solution are not a priori warranted. Connections among various deconvolution methods will be indicated, some practical recommendations will be given and examples from the deconvolution of X-ray diffraction profiles will be presented.

Surface treatment of zinc galvanized steel is carried out usually using chromate based baths. These baths are used for improvement of the corrosion resistance and enhancement of the chemical adhesion of organic coatings. Anticorrosive effects of the chromium conversion coatings were not completely exceeded yet by another kind of passivation. Toxicity of CrVI is a basic problem of chromate conversion coats. This paper presents the main results and conclusions of experimental study on zinc conversion layers based on vanadates, using a good CrVI bath as reference. Anticorrosive mechanisms were compared by the corrosion tests in saline cabinet. Inhibition effects were characterized by scanning electron microscopy, by X-ray dispersive spectrometry (EDS) associated X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy.

The aim of the paper is to present the possibilities of X-ray diffraction analysis for characterisation of surface layers after machining by using electro discharge machining (EDM) and electro chemical cutting (ECM), in comparison with "classical" grinding of steels. Residual macroscopic stress, crystallite size, microstress and phase composition were found for the mentioned methods of surface treatment. Anomalous diffraction profiles were observed especially after the method EDM. It can be caused by the bimodal distribution of crystallite size.

An excimer laser combined with magnetron sputtering was used for TiC-layer deposition. Various laser-magnetron configurations and deposition regimes were tested. The growth rate and the film-thickness homogeneity were studied. The film properties were characterized by XRD, Raman spectroscopy, scratch test, and microhardness measurements. Plasma plumes were detected by optical-emission spectroscopy. Films containing TiC nanocrystals embedded in a-C matrix were fabricated at room substrate temperature on large-area silicon substrates.

Thin iron oxide layers prepared "in situ" in the ultra high vacuum on polycrystalline iron substrate were investigated by electron spectroscopy methods-X-ray photoelectron spectroscopy (XPS) and elastic peak electron spectroscopy (EPES), using spectrometer ADES-400. The texture and the average grain size of the iron substrate foil have been examined by glancing angle X-ray diffraction (XRD). Qualitative and quantitative estimation of investigated oxide layers was made using (i) the relative sensitivity factor XPS method, (ii) comparison of binding energy shifts of Fe 2p photoelectron line and (iii) non-linear fitting procedure of Fe 2p photoelectron lines.Both, sputter-clean polycrystalline iron substrate and finally grown Fe2.2O3 layer, were investigated by the EPES method to measure the electron transport parameters used for quantitative electron spectroscopy, such as the electron inelastic mean free path (IMFP) values. The IMFPs were measured in the electron kinetic energy range 200-1000 eV with the Cu standard. The surface excitation parameters using Chen and Werner et al. approaches were evaluated and applied for correcting these IMFPs. The discrepancies between the evaluated parameters obtained using the above quantitative and qualitative approaches for characterising the iron oxide layers were discussed. (c) 2005 Elsevier B.V. All rights reserved.

The paper reports on a detailed investigation of microstructure and phase composition of rapidly solidified and annealed AlNi18.5 and AlNi17Zr1.8 ribbons. The ribbons were prepared by the melt spinning (planar flow casting) technique. The microstructure and phase composition have been studied by TEM and XRD. The specimens were annealed and subsequently subjected to microstructure investigations to asses their thermal stability. Rapidly solidified alloys are composed of a-Al and Al3Ni phase grains. No significant difference in the shape between Al and Al3Ni grains was found. The Al9Ni2 metastable phase was identified in the rapidly solidified AlNi17Zr1.8 alloy and the Al3Zr phase precipitates from the a-Al solid solution in the AlNi17Zr1.8 alloy after the high temperature annealing.

Textured and amorphous thin films were deposited by KrF laser ablation of neodymium doped potassium gadolinium tungstate, KGd1−xNdx(WO4)2 (Nd:KGW) single crystal in oxygen ambient atmosphere on MgO, YAP (YAlO3) and YAG (Y3Al5O12) substrates at temperatures up to 800°C. The influence of substrate nature and substrate temperature (Ts) on films crystallinity and morphology were studied by conventional X-ray diffraction (XRD), micro-Raman spectroscopy (μRS) and scanning electron microscopy (SEM). Related emission and excitation spectra and fluorescence decay were examined. The strongly textured polycrystalline Nd:KGW films with fluorescence spectra very close to those of bulk single crystal were deposited only on YAG substrate at higher Ts, whereas the smoother films were obtained at Ts=400°C on all types of substrates. Fluorescence properties of the films corresponding to the transitions from the 4F3/2 doublet to the 4I9/2, 4I11/2 and 4I13/2 multiplets, at about 890nm, 1.06μm and 1.3μm, bring a new information about the structure of the film at the scale of the Nd3+ ions environment, which could not be detected by XRD method. The fluorescence decay was almost exponential, with a lifetime of about 110μs for polycrystalline KGW films.

Measurements of elastic electron backscattering probabilities may provide the electron inelastic mean free paths (IMFP). This technique is known as elastic peak electron spectroscopy (EPES). The IMFPs in Ti can be determined from optical data by Tanuma et al., Gries or the TPP-2M predictive formulae. Studies on Si and Ni show a weak influence of surface roughness, but a stronger influence of atomic composition, density, texture, average grain size and surface excitations on the IMFPs. In the present work, the elastic electron backscattering probability and IMFPs are determined for Ti exposed to sputtering and annealing. The atomic composition of Ti is determined by XPS and texture and grain size is determined by x-ray diffraction (XRD). Ti samples exhibit no texture and grain size from 1 mum to 100 mum. For annealed samples the titanium hydride phase can be observed from the binding energy shift of Ti 2p XPS spectra. Scatter in the resulting IMFPs due to density and composition change (O and C contamination, and H from vacuum background) is negligible in comparison to scatter due to the grain size and standard used (Al and Cu). The IMFPs in Ti of grain size 1-10 mum are smaller than IMFPs in Ti of grain size 100 mum. These differences are explained by effects not accounted for in the calculations, i.e. the inelastic losses on the grain boundaries which are more pronounced in Ti of small grain size, and surface excitations which differ for Ti, Al and Cu. Copyright (C) 2004 John Wiley Sons, Ltd.

A new method of crystallite size determination has been applied to submicrocrystalline materials prepared by high-pressure torsion deformation. The method is based on the measurement of the small-angle diffuse scattering in the transmitted wave and requires thin foil samples and well-defined incoming plane wave. The physical information is encoded in the wave modification due to primary extinction in the crystallites.

The samples of the self-organized quantum dots, made of polar semiconductors, grown by the Stranski-Krastanow growth method, have the so called wetting-layer (WL). The lowest-energy extended states of the electronic excitations are expected to be the WL states. The coupling between these extended states and the electronic states localized in the individual quantum dots, may have an influence on the optical spectra of such samples in the sub-WL region of energy. This effect is studied, turning the attention first of all to the Frohlich's coupling between the electrons and polar optical phonons. The contribution of this interaction to the appearance of the sub-WL continuum in the optical spectra and to the level broadening of the localized states, pointed out in some experiments, is estimated.