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Zinc oxide (ZnO) was mechanically activated in air using a planetary ball mill using varying milling speeds and time. The obtained samples were analyzed by X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) and UV-Vis diffusion reflectance spectroscopy. The photocatalytic activity of the mechanically treated ZnO powders were investigated in the reaction of Malachite Green (MG) degradation in aqueous solution under UV-light irradiation. A decrease in the crystallite size (from 90 to 10 nm) accompanied by an increase of microstrains and lattice parameters were established applying different milling speeds. The agglomeration of the particles was observed by SEM analysis. The absorption spectra of the initial and mechanically activated ZnO samples show shifting of the band position from 360 to 330 nm, which can be related to decrease in the crystalline size. The ZnO powders activated at lower milling speeds (for shorter time intervals) exhibit highest photocatalytic activity.

The theoretical calculations indicated that the monoclinic low-temperature phase of silver telluride $$(\upbeta \hbox {-Ag}_{2}\hbox {Te})$$ is a new binary topological insulator with highly anisotropic single Dirac cone surface. We obtained $$\upbeta \hbox {-Ag}_{2}\hbox {Te}$$ crystal ingots containing few grains by the Bridgman method. We also deposited thin films of tellurium, $$\hbox {Ag}_{5}\hbox {Te}_{3}\hbox { and }(\hbox {Te+Ag}_{5}\hbox {Te}_{3})$$ by thermal evaporation method. The Raman spectra of $$\upbeta \hbox {-Ag}_{2}\hbox {Te}$$ , tellurium and $$\hbox {Ag}_{5}\hbox {Te}_{3}$$ were measured at three excitation wave lengths: 633, 515 and 488 nm. The Raman active modes of $$\upbeta \hbox {-Ag}_{2}\hbox {Te}$$ , tellurium and $$\hbox {Ag}_{5}\hbox {Te}_{3}$$ are situated at frequencies below 300 $$\hbox {cm}^{-1}$$ while vibrations of other phases appear at higher frequencies.

Two series of Fe-doped (5, 10 and 20 wt% Fe 2 O 3 ) ceria oxides were synthesized by mechanochemical mixing (MM) and impregnation (IM) methods. The Au catalysts (3 wt%) supported on these mixed oxides were tested in WGSR and PROX. Gold catalysts on supports prepared by IM exhibited WGS activity lower than that of gold on undoped ceria. Significantly better WGS performance was demonstrated over gold catalysts on supports synthesized by MM. The observed differences in the catalytic behavior were explained by the crucial role of the gold dispersion depending on the preparation method. The highest WGS activity of Au5FeCeMM catalyst was attributed to the cooperative catalytic work of Fe-modified ceria and magnetite with the highest extent of non-stoichiometricity. In contrast to WGSR, the catalytic behavior in PROX over gold catalysts on supports prepared by both methods did not differ significantly. Fe likely acted as a ceria modifier because no changes in Fe-phases and Fe valence state were observed upon reaction. The nanosized hematite particles covering the ceria grains in the case of the IM method could diminish the ceria basicity explaining the observed good and stable PROX performance over Au10FeCeIM catalyst in the presence of CO 2 and water.

Preliminary results on the production of new ceramic bricks by an innovative microwave-assisted sintering process employing MSWI bottom ashes are reported. Microwave heating technique was compared with a conventional thermal treatment with the aims to: (1) study the influence of heat treatment method on the crystallization behavior and on the microstructure of obtained samples; (2) define the crystallization evolution in microwave field; (3) gain an insight into the physical properties of the new samples. Higher crystallinity and new crystal phases were observed in the samples prepared by microwave heating, where precipitation of new sodium rich crystal phases was observed, together with quartz and anorthite, formed in the conventionally prepared samples. The possibility to obtain novel bricks with huge waste amount, in a very short thermal cycle and at relatively low temperatures was demonstrated with significant reductions in the energy demand for their production. Finally, the samples obtained by microwave-assisted sintering are characterized by improved mechanical properties.

We report an experimental investigation on room-temperature synthesis of porous metal - semiconductor plasmonic nanocomposites by using laser deposition and annealing with nanosecond pulses. Ag/ZnO nanostructures are elaborated by using Ag-doped ZnO targets and the effects of silver concentration and laser annealing on the morphology and optical properties of the Ag/ZnO embedded nanostructures are studied. Ag-doped ZnO thin films are deposited by pulsed laser deposition on quartz substrates and subsequently laser annealed. Homemade Ag/ZnO targets with a silver doping concentration of 2, 4 and 6 at.%, prepared by ceramic technology, are exploited in the film deposition process. Then, the influence of laser irradiation on the microstructure and plasmon resonance absorption of the samples is investigated for three values of the number of laser pulses used for annealing. As the number of laser annealing pulses increases the resonance absorption is magnified. The net-like morphology of nanowires transforms to nanoparticles with increasing the silver concentration at the fixed number of ten laser annealing pulses. The composite systems show interesting plasmonic properties, which can be easily tuned by controlling the nanostructures morphology from nanowires through nanochains to nanoparticles. The experimental optical properties are in agreement with predictions of theoretical calculations showing that the extinction efficiency of AgNPs in ZnO environment peaks at about 490 nm.

ZnO nanostructures were fabricated on noble-metal (Au-Ag alloy) coated substrates by pulsed laser deposition. We studied the influence of the laser wavelength used for ablation on the morphology, growth mechanism, and optical properties of the nanostructures. ZnO nanostructures produced by UV (355 nm) pulsed laser deposition possessed a mixed-structures morphology, composed of nanorods (mean diameter of 25-50 nm) and large-size nanobelts. The density of these structures could be controlled by varying the Au/Ag ratio in the alloy layer. Samples deposited by pulsed laser deposition at VIS wavelength (532 nm), instead, presented a dense agglomeration of nanoparticles (nanorods) with a mean diameter in the range of 40-55 nm. The growth of the ZnO nanostructures followed a vapor-solid or vapor-liquid-solid mechanism depending on the catalyst layer composition when a UV source was used for ablation. The presence of Au and Ag on the ZnO surface was a clear indication for a vapor-liquid-solid mechanism of growth for nanostructures deposited by using a VIS radiation. A narrow peak centered at 379 nm in UV band and a broadband visible emission with a peak at 540 nm were observed in all nanostructures. The UV-deposited sample exhibited a stronger UV emission, while the visible emission was predominant for the sample deposited by VIS ablation. (C) 2017 Elsevier B.V. All rights reserved.

A new approach for the synthesis of chemically stabilized β-cristobalite-like glass-ceramic materials is developed. It is based on an activated reaction sinter-crystallization process of compacted powder mixtures at relatively low temperatures (1400–1450°C) and short heat treatment times. To facilitate homogeneous dopant distribution and thus the formation of a high content of βx-cristobalite-like phases, possessing a very low thermal expansion coefficient, the batch components are introduced in a chemically, mechanically, or thermally preactivated form. In this way, the high-temperature glass premelting usually employed in the “classical” synthesis of glass-ceramics is avoided. Using different, mutually complementary techniques of analysis it is revealed that optimal refractory properties are achieved with glass-ceramics containing αx- and βx-cristobalite solid solutions with close values of the lattice parameters. In this case, the transformation between these two cristobalite-like solid solutions proceeds instead by a first-order displacive transition, by a process exhibiting features characteristic for both a suppressed first-order phase change and a second-order λ-type phase transitions. The refractory properties of the glass-ceramic materials thus synthesized and the possibility to use various forming techniques open many fields for their application.

Microcomposites consisting of TiO2 (or Ce-doped TiO2) and ThO2 (0.5–2% of the TiO2 mass) are produced by sol-gel synthesis of TiO2 in presence of ThO2. X-ray diffraction study reveals the effects of ThO2 (compared to the ThO2-free TiO2, obtained by the same method) on the anatase interplanar distances, crystallites size and phase composition. The photocatalytic tests in presence of the composites under UV irradiation reveal an increase of the Malachite Green degradation rate constant. The effect depends on the Th relative content, temperature of annealing of the catalyst and addition of other doping agent. The highest photocatalytic activity is observed for TiO2 obtained at 550°C and containing 1% ThO2. The composite exhibits activity in dark, also. The presence of Ce4+ ions is not an obligatory requirement for the realization of the ThO2 effect. The reported results suggest that the radioactivity of the Th and/or its decay products is one of the main factors responsible for the increased photocatalytic activity of TiO2.

Three new ceramic batches with no traditional fluxes and 30, 50 and 70 wt.% blast furnace slag were studied. The processes of phase formation and densification were estimated in non-isothermal conditions by differential thermal analysis and dilatometry, respectively. After that the degrees of sintering, obtained after heat-treatment at different temperatures and times, were evaluated measuring the variations of linear shrinkage and water absorption. The structures of final materials and their phase compositions were studied with scanning electron microscopy, pycnometry and X-ray diffraction. Mechanical properties of the final ceramics were also measured. The obtained ceramics are characterized with a narrow sintering interval at 1200–1220 °C and good degrees of densification. Due to the formation of pyroxene and anorthite solid solution the new materials show high crystallinity. As a result, the measured bending strength and hardness surpass the values of traditional building and tiling materials.

The applicability of mechanochemistry to produce uranium–lanthanoid mixed oxides is presented. Phase homogeneous uranium–cerium solid solutions of the type Ce x U1−x O2 (x = 0.3 ÷ 0.95) and polyphase systems containing La y U1−y O2+x (y = 0.12) were prepared by mechanochemical activation in air of sol–gel produced precursors. The possibility for synthesis of urania–lanthania solid solution by mechanochemical interaction of La2O3 with sol–gel produced U (IV,VI) oxide is established. The crystal structures of the obtained oxides before and after the mechanochemical treatment are analysed by the use of X-ray diffraction method. The size of the crystallites (8–16 nm), lattice parameters, crystallite strains and densities of the oxides are calculated by BRASS program for Rietveld calculation.

Method for synthesis of UO2+x and uranium–thorium mixed oxides by using sol–gel method and mechanochemical activation is proposed. The synthesis of UO2+x and solid solutions with equal amount of metals or enriched to one of them is performed by external gelation process, thermal decomposition of the sol–gel products in air and subsequent mechanochemical activation in air in stainless steel vessels. The crystal structures of the obtained oxides before and after the mechanochemical treatment are analysed by the use of X-ray diffraction method. Quantitative phase analysis and calculations of the size of the crystallites, lattice parameters, and densities of the oxides are performed by BRASS program for Rietveld calculation. The proposed method leads to decrease of the lattice parameters and thus to higher density of the obtained oxides with crystallites size in the range of 12–16 nm.

In this work, erbium, and erbium and ytterbium co-doped YVO 4 waveguiding thin films were deposited on amorphous SiO 2 substrates by pulsed laser deposition (PLD) and ultraviolet-assisted pulsed laser deposition (UVPLD). The influence of the deposition technique on the structure, morphology, and optical properties of the films was investigated. At lower dopant concentrations the films prepared by UVPLD show better crystallinity and optical properties. All the samples show preferred orientation of the (001) zone axes parallel to the substrate surface. The polycrystalline samples show difference in the refractive indexes ∆ n (∆ n = n TE − n TM ) for the TE and TM polarizations.

In this work, ZnO nanostructures were fabricated on Ag-coated substrates by pulsed laser deposition. Ag was incorporated into ZnO nanostructures during the growth by using a composite, or mosaic, target. The effect was studied of Ag doping on the morphology, structure, composition, and photoluminescence of the ZnO nanostructures. It was found that the increase of the dopant concentration leads to a deterioration of the crystalline structure, as well as to a change of the sample morphology. It was also found that the manner of incorporating Ag into the ZnO matrix affects the photoluminescent performance of the nanocomposite coatings.

Lithium manganese titanium spinels, LiMn 2− y Ti y O 4 , (0.2≤ y ≤1.5) have been synthesized by solid-state reaction between TiO 2 (anatase), Li 2 CO 3 and MnCO 3 . Li + was leached from the powdered reaction products by treatment in excess of 0.2 N HCl at 85 °C for 6 h, under reflux. The elemental composition of the acidic solution and solid residues of leaching has been determined by complexometric titration, atomic absorption spectroscopy and X-ray fluorescence analysis. Powder X-ray diffraction was used for structural characterization of the crystalline fraction of the solid residues. It has been found that the amount of Li + leached from LiMn 2− y Ti y O 4 decreases monotonically with increasing y in the interval 0.2≤ y ≤1.0 and abruptly drops to negligibly small values for y >1.0. The content of Mn and Li in the liquid phase and of Mn and Ti in the solid (amorphous plus crystalline) residue, were related to the composition and cation distribution in the pristine compounds. A new formal chemical equation describing the process of leaching and a mechanism of the structural transformation undergone by the initial solids as a result of Li + removal has been proposed.

We report a novel approach for fabrication of cubic ZrWMoO8 applying a melt quenching method. The stoichiometric mixture of ZrO2, WO3 and MoO3 in a 1:1:1 M ratio was melted and quenched at room temperature by pouring the melts between two metal plates. The quenched sample was characterized by X-ray diffraction (XRD), differential thermal analysis (DTA) and scanning electron microscopy (SEM) analysis. As quenched material is polyphase contains above 70% ZrWMoO8. The obtained composite is thermal stable up to 930 °C. The ZrWMoO8 was indexed as cubic with a lattice parameter a = 9.1263 (3) A calculated by the “PowderCell” program. By SEM observation it was established that the microstructure of bulk composite material is built up of one-direction orientated agglomerates with cuboid crystal morphology.

Doubly doped LiMn 1.99− y Li y M 0.01 O 4 (M = Al 3+ , Ni 2+ , Cr 3+ , Co 3+ ; y = 0.01 and 0.06) spinels have been synthesized by the sucrose-aided combustion method. Combined TG/DTA and XRD studies have shown that stoichiometric single-phase spinels are formed after annealing of the samples at 700 °C for 1 h. The samples obtained are nanocrystalline materials having a narrow size-distribution and a coherent domain size between 40 and 60 nm, depending on the amount of fuel (sucrose) used in the synthesis. The influence of the Li-excess, the type of M n + -dopant cation and the amount of fuel used in the synthesis on the electrochemical behavior of the spinels in a Li-cell at room and at elevated temperature (55 °C) has been studied. At 25 °C all the spinels synthesized have a good capacity retention after 100 cycles, QRt-100 > 92%. At 55 °C the increase of the Li-excess improves the cycling performances. Rate capability studies show that the spinels retain >90% of their capacity even at 5 C rate. The synergic effect of the Li-excess and the particle size on the electrochemical properties of the spinels as cathode material has been settled. The LiMn 1.93 Li 0.06 M 0.01 O 4 , (M = Al 3+ , Ni 2+ ) spinels, with cyclabilities >99.9% by cycle at both 25 and 55 °C, and high rate capabilities, are the ones that show the best electrochemical properties.

Erbium, and erbium and ytterbium co-doped YVO4 waveguiding films were deposited on MgO/Si substrates by PLD. The samples were post-annealed at two different temperatures in air atmosphere. The influence on the crystalline structure and waveguiding properties of the films at these annealing temperatures for two dopant concentrations was investigated. Layers annealed up to 900 °C are polycrystalline. The dominant fraction of YVO4 crystallites exhibited preferred orientation of the (0 0 1) zone axes parallel to the substrate surface. The polycrystalline samples show difference in the refractive indexes Δn (Δn = nTE − nTM) for TE and TM polarizations.

The anodic behavior, corrosion resistance and protective ability of Zn and alloyed Zn–Co (∼3 wt.%) nanocomposite coatings were investigated in a model corrosion medium of 5% NaCl solution. The metallic matrix of the layers incorporates core–shell nano-sized stabilized polymeric micelles (SPMs) obtained from poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) block co-polymers. The protective properties of the composite coatings were evaluated using potentiodynamic polarization technique, polarization resistance measurements and powder X-ray diffraction. The sizes and distribution of the stabilized polymeric micelles in the starting electrolytes used as well as in the metal matrices of the layers were investigated using scanning and transmission electron microscopy. The results obtained are compared to those of electrodeposited Zn and Zn–Co (∼3 wt.%) alloy coatings at identical conditions and demonstrate the enhanced protective characteristics of the Zn nanocomposites during the investigating period. The influence of the SPMs on the corrosion resistance of the nanocomposite layers is commented and discussed.

Magnetite (Fe3O4) nanoparticles were crystallized from soda alumina borosilicate glasses with the composition (24−y)Na2O·yAl2O3·14B2O3·37SiO2·25Fe2O3, where y = 8, 12, 14, 16 mol%. All samples are phase separated into magnetite core, enriched in iron oxide, and a glass shell. The magnetic core phase consists of nanocrystallites with sizes ranging between 25 and 40 nm, depending on the respective glass composition. All samples show characteristic well-defined hysteresis loops at room temperature, indicating that the magnetite particles are ferrimagnetic. No evidence for the existence of superparamagnetic particles is found by measuring the ZFC and FC thermomagnetic curves.

Gold supported catalysts on ceria-alumina, prepared by different methods have been studied in the WGS reaction. For the synthesis of the mixed ceria-alumina support two methods were applied—a new method of mechanochemical activation and well known ceria washcoating on alumina. Gold catalysts on ceria-alumina, prepared by mechanochemical activation show a high and stable WGS activity. A correlation between redox activity of the catalysts, estimated by TPR and the catalytic activity of the samples was observed. The introducing of alumina to ceria by mechanochemical activation causes formation of oxygen vacancies, located mainly on the catalyst surface. In the freshly prepared catalysts an optimum between a part of positively charged nano-gold particles, Ce 3+ and oxygen vacancies should be the crucial factor for the good performance of WGS catalysts. In the course of redox reaction the active complex is being changed because of the electron transfer between gold and ceria through oxygen vacancies. A positive effect of alumina on the catalysts stability with respect to avoiding gold and ceria particles agglomeration was confirmed, as well.

LiFe 0.5 Ti 1.5 O 4 was synthesized by solid-state reaction carried out at 900 °C in flowing argon atmosphere, followed by rapid quenching of the reaction product to room temperature. The compound has been characterized by X-ray powder diffraction (XRD) and 57 Fe Mossbauer effect spectroscopy (MES). It crystallizes in the space group P 4 3 32, a = 8.4048(1) A. Results from Rietveld structural refinement indicated 1:3 cation ordering on the octahedral sites: Li occupies the octahedral (4 b ) sites, Ti occupies the octahedral (12 d ) sites, while the tetrahedral (8 c ) sites have mixed (Fe/Li) occupancy. A small, about 5%, inversion of Fe on the (4 b ) sites has been detected. The MES data is consistent with cation distribution and oxidation state of Fe, determined from the structural data. The title compound is thermally unstable in air atmosphere. At 800 °C it transforms to a mixture of two Fe 3+ containing phases – a face centred cubic spinel Li (1+ y )/2 Fe (5−3 y )/2 Ti y O 4 and a Li ( z −1)/2 Fe (7−3 z )/2 Ti z O 5 – pseudobrookite. The major product of thermal treatment at 1000 °C is a ramsdellite type lithium titanium iron(III) oxide, accompanied by traces of rutile and pseudobrookite.

Chromium doped spinels LiCrYMn2−YO4 (0.2≤Y≤0.8) has been synthesized by the sucrose-aided combustion procedure. The thermal behaviour, phase homogeneity and structural characteristics of the samples were studied by thermal analysis, coupled mass spectrometry, and room-and high-temperature X-ray diffraction methods. It was found that the ‘as prepared’ samples contained residual organic impurities undetectable for X-ray diffraction, that burn out completely at 400°C. Samples treated between 400 and 750°C are single phase spinels, whose crystallites size increase from 10 to 50 nm on increasing the temperature. Cr-doping enhances the thermal stability of the spinels, which augments on increasing the Cr content Y. The enhanced thermal stability of the spinels has been accounted for based on the high excess stabilization energy of Cr3+ in octahedral ligand field.

In this work, thin YVO 4 films were deposited on amorphous SiO 2 substrates by pulsed laser deposition (PLD). Ceramic targets of pure and doped (Er and Er, Yb) YVO 4 were prepared and used for ablation. The influence of the substrate temperature and oxygen pressure applied during the depositions was investigated. Crystalline films were obtained at temperatures higher than 500 °C. The films with the best crystallinity were obtained at 5 Pa oxygen pressure and 700 °C substrate temperature. All the films are transparent in the visible and near infrared region of spectra. The crystalline samples show difference in the refractive indexes Δ n (Δ n = n TE − n TM ) for the TE and TM polarizations. It was evaluated to be about 0.08.

The thermolysis of the ill-known γ-MnC2O4·2H2O is investigated applying DTA, TG, DSC, FT-IR, SEM, BET and Rietveld XRD phase analyses for thorough characterization of the starting compound and its calcined products. The dehydration proceeds in one step with ∆H = 149 kJ mol−1 (reported for the first time). Primary decomposition product is Mn3O4 ([Mn2+Mn2 3+]O4) with high specific surface area. During its formation, the oxidation of Mn3+ species to Mn4+ starts, followed by oxidation of Mn2+–Mn3+, thus leading to formation of metastable Mn5O8 ([Mn2 2+Mn3 4+]O8) and Mn2O3. Before complete precursor decomposition under non-isothermal conditions, the reduction of Mn4+–Mn3+ occurs, forming an additional amount of Mn3O4. After isothermal annealing of γ-MnC2O4·2H2O in the range of 573–823 K, Mn3O4 is detected as a major product in all samples. Mn5O8 is identified after calcination at 573, 673, 723 K, and its amount decreases gradually in this order. Cubic Mn2O3 appears after heat treatment at 673 K; its content varies between 13 and 23 % in the range of 673–773 K and becomes close to that of Mn3O4 at 823 K. The application of the same experimental conditions as in the investigation of α-MnC2O4·2H2O and MnC2O4·3H2O allows an objective comparison of the nature and the peculiarities of the thermal decomposition of different crystal forms of manganese oxalate.

Metastable orthorhombic (y) ZrW 2 O 8 was obtained by fast cooling of the melt of a stoichiometric mixture of ZrO 2 and WO 3 . Heating of the as-quenched sample at 600 °C for 15 h led to the full transition of the orthorhombic (y) to the cubic (a) ZrW 2 O8 polymorph. The average crystallite sizes of the obtained ZrW 2 O 8 phases were in the range of 50-80 nm. The morphology of the powdery products was characterized by scanning electron microscopy.

In the present work, thin zirconia films were prepared by pulsed laser deposition at different substrate temperatures and oxygen partial pressures. The substrate temperature was varied from 400 °C to 600 °C, and the oxygen pressure, from 0.01 to 0.05 mbar. The effect was investigated of the substrate temperature and oxygen pressure on the formation of m-zirconia and t-zirconia phases.The formation of a cubic phase of ZrO2 by using targets doped with 3 and 8 mol % content Y2O3 was also investigated. The variation in the optical properties was studied and discussed in relation with the zirconia films' microstructure.

The title compound, 3-acetyl-6-methoxy-2H-1-benzopyran-2-one, C12H10O4, Mr = 218.20, crystallizes in the triclinic system, space group P1, with cell constants a = 5.424(1)A, b = 8.409(2)A, c = 11.579(2)A, α = 104.58(2)°, β = 99.29(1)°, γ = 90.97(2)°, V = 503.49(17)A3 and Z = 2.

Temporary scaffolds that mimic the extracellular matrix’s structure and provide a stable substratum for the natural growth of cells are an innovative trend in the field of tissue engineering. The aim of this study is to obtain and design porous 2D fibroin-based cell matrices by femtosecond laser-induced microstructuring for future applications in muscle tissue engineering. Ultra-fast laser treatment is a non-contact method, which generates controlled porosity—the creation of micro/nanostructures on the surface of the biopolymer that can strongly affect cell behavior, while the control over its surface characteristics has the potential of directing the growth of future muscle tissue in the desired direction. The laser structured 2D thin film matrices from silk were characterized by means of SEM, EDX, AFM, FTIR, Micro-Raman, XRD, and 3D-roughness analyses. A WCA evaluation and initial experiments with murine C2C12 myoblasts cells were also performed. The results show that by varying the laser parameters, a different structuring degree can be achieved through the initial lifting and ejection of the material around the area of laser interaction to generate porous channels with varying widths and depths. The proper optimization of the applied laser parameters can significantly improve the bioactive properties of the investigated 2D model of a muscle cell matrix.