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The results of the present Q-band electron spin resonance (ESR) investigation on amber colored cubic boron nitride (cBN) crystalline superabrasive powder (BORAZON CBN400) offer further support to the hypothesis that impurity ions with high natural abundant zero nuclear spin isotopes, distributed non-uniformly, are involved in the structure of the observed paramagnetic centers. One could thus explain the absence of any hyperfine structure in the multifrequency electron spin resonance spectra of both presently and previously investigated cBN crystalline powders and single crystals. The scanning electron microscopy, cathodoluminescence and photoluminescence studies performed on single crystallites selected from the same cBN400 batch further confirm the presence of electro- and photo-luminescent active impurity related centers, non-uniformly distributed in the cBN crystallite host lattice. The observation of an intense and reproducible thermoluminescence spectrum, up to high radiation doses, attributed to several trapping centers involving impurities, is also reported here.

Previous electron spin resonance investigations correlated with data from cathodoluminscence and photoluminescence measurements have shown that impurity ions consisting mainly of isotopes with zero nuclear moments are involved in the structure of the observed paramagnetic point defects. In the present microstructural and compositional investigation we demonstrate that oxygen, carbon and silicon impurity atoms exhibiting low natural content of isotopes with non-zero nuclear spin are indeed present in cBN crystallites selected from amber coloured BORAZON CBN400 and CBN 500 super abrasive powders, as well as in the black coloured BORAZON CBN1000 and CBN Type 1. It is also shown that aggregates of impurity atoms are present next to the extended cBN lattice defects, which could explain the non-uniform distribution of the electro- and opto-active impurities reported in a spectroscopy investigation.

Sm3+, Pr3+ and Dy3+-doped Ca3Nb1.6875Ga3.1875O12 - CNGG and Ca3Li0.275Nb1.775Ga2.95O12 - CLNGG crystals are of interest as solid-state laser materials emitting in the yellow-orange spectral range, especially for diode pumping due to their partially disordered nature. In this work, for the first time to our knowledge, single crystals of Sm, Pr and Dy-doped CNGG and CLNGG crystals were grown by the Czochralski method. For the doping of CNGG and CLNGG crystals, five new stoichiometric garnets were synthesised by solid-state reaction method: praseodymium-gallium-garnet (PrGG), dysprosium-gallium-garnet (DyGG) and praseodymium-lithium-niobium-gallium-garnet (PrLNGG), samarium-lithium-niobium-gallium-garnet (SmLNGG), and dysprosium-lithium-niobium-gallium-garnet (DyLNGG). Samarium-gallium-garnet (SmGG) was also sintered and used for the doping of Sm:CNGG crystal. Structural properties of sintered materials and grown crystals were investigated by X-ray diffraction and the chemical compositions of the grown crystals were determined by inductively coupled plasma atomic emission spectrometry (ICP-AES) method. The spectroscopic investigations of the grown crystals have shown that they are promising laser materials in the yellow-orange spectral range.

We report a study related to the influence of heat treatment (up to 300 °C) on the structure of GaSb\GeTe, SnSe\GeTe and GaSb\SnSe stacked phase change memory films and of their counterparts with Hf thin film barrier between the layers. Samples were prepared by pulsed laser deposition and investigated by X-ray reflectometry and X-ray diffraction in order to evaluate the inter-films diffusion and the temperature threshold where this process is initiated. The thickness and mass density variations of films after each heat treatment, as well as the efficiency of hafnium barrier film, to eliminate potential atomic diffusion issues, were investigated.

Green compacts of B 4 C or B 4 C added with 1 vol% graphite were infiltrated with molten Si and subsequently were subject of processing by floating zone partial re-melting (FZPR). In FZPR only the low temperature fusible component, in this case Si, is melted. A fully dense B 4 C-based ceramic is obtained. It contains free-Si, SiC and B 4 C. In the center of the FZPR ceramic without graphite addition, the amount of Si is decreased when compared to the infiltrated material. Some impurity elements such as Al, Fe, or Ti detected in the raw B 4 C powder are preferentially gathered at the edges of the sample. In the sample added with graphite, formation of a high amount of SiC in the infiltrated material hinders Si shift from the center to the edges. The pulling rate and the particle size of the B 4 C raw powders are also important. It is recognized that sintering of powders larger than 10–20 µm is usually difficult: our approach is demonstrated to be suitable for processing of B 4 C powders with a very different particle size, from 10 to 250 µm. The FZPR ceramic had a Vickers hardness of 9–38 GPa depending on location of the indentation imprint and on the sample. A tensile strength of 114–188 MPa that is up to about 2–3 times higher than for the infiltrated material was recorded. Work indicates that the proposed processing approach offers extended control possibilities towards fabrication of new composite materials not available by traditional technologies.

Thermal behavior of repa-germanium (C 6 H 10 Ge 2 O 7 , Ge-132) during heating in air or in argon is investigated using DSC-TGA, XRD, SEM, TEM, and FT-IR measurements. Nine domains of thermal transformations were identified from room temperature to 1200 °C, in air or argon. The first reversible transformation is below 220 °C and it was assigned to an isomerization process, based on DSC, XRD and IR measurements. The next five transformation domains (220–910 °C) are decompositions accompanied by weight loss. The main product of thermal decomposition is Ge. The next transformation domain (910–970 °C) corresponds to melting of Ge, both in argon and air. In the air, this step is followed by oxidation of Ge (970–1100 °C) and, finally, by melting of GeO 2 . Amorphous phases formed between 220 and 720 °C. Observed processes are discussed based on crystal chemistry and bonds dynamics considerations.

Disordered Sm 3+ doped Y 3 Sc x Al 5-x O 12 (Sm:YS x AG) polycrystalline ceramics with compositional parameter x = (0.05, 0.5, 1, 2) and different Sm 3+ ions concentrations were obtained by solid state reaction method. XRD investigations show the linear increase of the lattice constant with compositional parameters x. New spectroscopic data obtained from high resolution optical absorption and emission spectra of Sm 3+ doped YS x AG ceramics reveal composition effects on Sm 3+ optical spectra: modification of the shapes and shifts of the lines, presence of the additional satellites and unresolved multicenter structure, etc. The analysis of these data allowed us to establish a partial structure of Sm 3+ energy levels in Sm:YS x AG ( x = 2) ceramics. The emission kinetics of the 4 G 5/2 level for different Sm 3+ concentrations and Sc content in Sm:YS x AG were measured and analyzed.

Because of the unique properties of the ferroelectric perovskite particles with a well-defined anisotropic form like shape- and size dependent at low dimensions they have all the attention of the scientific world. Extensive morpho-structural techniques will be used to characterize the piezoelectric material.

We report results regarding the in vitro toxicology of γ-Bi2O3 represented by its isomorphous phase Bi12TiO20 (γ-BTO). The γ-BTO microparticles were synthesized by two methods: coprecipitation from a bismuth nitrate–tetrabutyl titanate solution and solid state reaction of Bi2O3 and TiO2 oxides. The structural and morphological characteristics of the obtained materials were determined using X-ray diffraction (XRD), selected area electron diffraction (SAED), transmission (TEM) and scanning (SEM) electron microscopy. The elemental composition was investigated using energy dispersive spectrometry (EDS). The cytotoxicity and oxidative/nitrosative stress (intracellular reactive oxygen species (ROS) and nitric oxide (NO) release) induced by the studied microparticles in HepG2, SH-SY5Y and 3T3-L1 cell cultures were determined using the MTT, DCF-DA (2′,7′-dichlorfluorescein-diacetate) and Griess methods respectively. Depending on the cell type and γ-BTO concentration, results showed only weak cytotoxic effects after 24 h of γ-BTO exposure and cell proliferation effects for longer treatment times. Only reduced NO release increases (corresponding to high γ-BTO concentrations) were detected in case of SH-SY5Y and 3T3-L1 cells. The intracellular ROS production (higher for HepG2 cells) appeared inversely proportional to the γ-BTO concentration. The obtained results indicated a promising in vitro biocompatibility of γ-BTO and encourage further studies regarding its potential for biomedical applications.

A1. Electrical properties A1. Surface structure A1. X-ray diffraction A3. Reactive magnetron sputtering epitaxy B1. Titanium carbide abstract Epitaxial TiC films were deposited on MgO (001) by DC magnetron sputtering in a reactive atmosphere of Ar and CH4 at 800 1C. The films elemental composition and chemical bonding was investigated by Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS) and micro-Raman spectroscopy. The crystallographic structure, investigated by X-ray diffraction, exhibited an increased degree of (001) orientation with the film thickness, with a cube-on-cube epitaxial relationship with the substrate. The films morphology and electrical properties were determined by atomic force microscopy (AFM) and Hall measurements in Van der Pauw geometry. The influences of the film thickness (57-545 nm) on the morphological and electrical properties were investigated. The thinnest film presented the lowest resistivity, � 160 mΩ cm, showing an atomically flat surface, while higher values were obtained for the thicker films, explained by their different morphology dominated by low aspect ratio nanoislands/ nanocolumns.

Nanocomposites based on TiO2 aerogel and Ag nanoparticles have been successfully obtained through different synthesis methods and their specific surface areas have been determined by N2 sorption (BET method). The photocatalytic potential for salicylic acid degradation has been evaluated. It was found that under visible light irradiation, all synthesized nanocomposites exhibit higher photocatalytic activity than the commercially available Aeroxide P25. By correlating the structural parameters with the photocatalytic performances, it has been found that the Ag nanoparticles and brookite phase presence alongside the anatase play important roles on the visible photocatalysts behavior. For the Ag containing samples with mixed anatase–brookite phases, it has been observed that the visible photocatalytic performance decreases with the increase in brookite crystalline phase content. On the other hand, the addition of Ag nanoparticles results, as expected, in a clear enhancement of the visible photocatalytic activity.

Ba(Zn1/3Ta2/3)O3 (BZT) thin films were grown on Pt-coated Si substrates at 500 °C substrate temperatures by pulsed electron beam deposition method and post-annealed at 600 and 650 °C for 1 h. The X-ray diffraction patterns indicate that the as-grown films are partially crystallized but single-phase cubic perovskite structure was formed in annealed films. The temperature dependence of the dielectric constant of the BZT films was recorded in the − 100 to + 100 °C range. The annealing treatment induces a decrease of the temperature coefficient of the dielectric permittivity with an order of magnitude, from 2000 to 100 ppm/°C. The influence of the annealing treatments on the temperature behavior of the BZT films was evidenced; a dielectric constant of about 21 at room temperature was obtained for the films annealed at 650 °C.

TiO2 nanopowders, doped with Fe3+ and Eu3+ were obtained by high-energy ball milling and their physical properties were investigated as a function of the doping content and ball milling time. A noticeable red shift and high photoactivity in the degradation and catalytic oxidation reactions of styrene and phenol were found for all doped specimens.

Iron- and europium-doped (≤1 at.%) TiO 2 nanoparticles powders have been synthesized by a hydrothermal route at 200 °C, starting with TiCl 4 , FeCl 3 ·6H 2 O and EuCl 3 ·6H 2 O. The structure, morphology and optical peculiarities were investigated by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), extended X-ray absorption fine structure (EXAFS), Mossbauer spectroscopy and UV–vis measurements. The photocatalytic performance was analysed in the photodegradation reaction of phenol. Rietveld refinements of XRD patterns reveal that the as-prepared samples consist in iron- and europium-doped TiO 2 in the tetragonal anatase structural shape, with particle size as low as 15 nm. By means of Mossbauer spectroscopy on both 57 Fe and 151 Eu isotopes as well as by EXAFS analyses, the presence of Fe 3+ and/or Eu 3+ ions in the nanosized powders has been evidenced. It was found that iron and europium ions can substitute for titanium in the anatase structure. From the UV–vis reflection spectra, by using the transformed Kubelka–Munk functions, the band gap energy ( E g ) of the hydrothermal samples has been determined in comparison with that of Degussa P-25 photocatalyst. A decrease of E g from 2.9 eV found for Degussa photocatalyst to 2.8 eV for the titania doped with 1 at.% Fe has been evidenced, indicating a valuable absorption shift (∼20 nm) towards visible light region. However, the best photocatalytic activity in the photodegradation reaction of phenol was evidenced for the hydrothermal sample, TiO 2 : 1 at.% Fe, 0.5 at.% Eu, in both UV and visible light regions. The photocatalytic activities of iron-doped and iron–europium-codoped samples are high and practically the same only in visible light. The photocatalytic properties in correlation with the structural and optical peculiarities of the hydrothermal samples are discussed.

A sandwich structure of four double layers of Ag (5 nm)/As 2 S 3 (82.7 nm) has been prepared by Pulsed Laser Deposition (PLD) method. The effect of broadband light on the multilayer structure has been investigated. The X-ray reflectivity (XRR) patterns after different irradiation times have been measured. Although the fully intermixing of Ag and As 2 S 3 layers should be expected during irradiation with visible light, however even after 5 h of irradiation the intermixing is not completed. The characteristic features of XRR diagrams for long irradiation times have been interpreted by scattering of X-ray radiation on clusters of Ag or Ag–As 2 S 3 .

The synthesis of a new garnet, Er3Li0.275Nb0.275Ga4.45O12 (ErLNGG), by solid-state reaction, is reported. A comparison of the fluorescence spectra of Er3+ in ErLNGG, Er-doped (0.1 at.%) calcium lithium niobium gallium garnet (CLNGG), and Er(50 at.%):CLNGG is presented. The narrowing of luminescence lines suggests an ordering of the partially disordered CLNGG with the increase of erbium concentration.

The M-shell satellite structure of W X-ray emission lines excited by electron bombardment is investigated by a high resolution single crystal spectrometer, and the obtained structure is further compared with calculated transition energies obtained by the Relativistic Density Functional method. The transition hole states situated in the N- and O-shells—due to Coster–Kronig transitions—correspond to the parts of the spectra situated in the close neighbourhood of the diagram transition (0.7–4.4 eV).

The photoabsorption cross-section in Xe has been measured in order to determine the features of the shake processes resulting from multiple electron excitations as a function of photon energy. Double-electron transitions of [1s4d], [1s4p], [1s4s], and [1s3d] have been detected.