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Synthesis of NiO nanoparticles by sol-gel technique

Abstract

NiO nanoparticles were fabricated by sol-gel route using ammonium hydroxide and nickel nitrate as precursors. The NiO nanoparticles were calcinated at 400 °C and 1000 °C. The nanoparticles were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), vibrating sample magnetometer (VSM), thermogravimetry analysis/differential thermal analysis (TGA/DTA). The structural properties were evaluated by X-ray diffraction (XRD). XRD confirmed the formation of well-crystallized and high purity NiO phase. The XRD showed that the peaks were sharpened and the crystallite size increased as the calcination temperature increased. The average crystallite size ranged from 12 nm to 20 nm, when calcined at temperatures 400 °C and 1000 °C, respectively. Fourier transform infrared spectroscopy (FT-IR) revealed the chemical composition and confirmed the formation of NiO nanoparticles. The nanoparticles showed paramagnetic behavior.

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Synthesis of Ag-ZnO composites via ball milling and hot pressing processes

Abstract

Ag — 8 wt. % ZnO composites were synthesized by ball milling, heat treating and hot pressing of silver and zinc oxide powder mixtures. The crystalline size and microstrain of the milled powders before and after heat treatment were determined by Debye-Scherrer andWilliamson-Hall methods. It was shown that heat treatment resulted in decrease of microstrain and increase in the crystallite size of the milled powders. The effect of uniaxial pressure magnitude and duration of hot pressing at 550 °C on the final density of the powder compacts were investigated. The results showed that both plastic flow and atomic diffusion mechanisms affected densification of the composite powders during the hot pressing process. However, the latter one had more effective role on the density of the hot-pressed samples. The synthesized composites showed homogenous microstructure with relatively high density and hardness.

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Effect of calcination temperature on photocatalytic activity of TiO2. Photodecomposition of mono- and polyazo dyes in water

Effect of calcination temperature on photocatalytic activity of TiO2. Photodecomposition of mono- and polyazo dyes in water

The presented studies have focused on the influence of TiO2 properties, such as crystalline phase, crystallite size and surface area, on the effectiveness of degradation of azo dyes in water under UV irradiation. Two monoazo dyes: Acid Red 18 (AR18, C20H11N2Na3O10S3) and Acid Yellow 36 (AY36, C18H14N3NaO3S), and one polyazo dye Direct Green 99 (DG99, C44H28N12Na4O14S4) were applied as model compounds. The photocatalysts were prepared from a crude titanium dioxide obtained directly from the production line (sulfate technology) at the Chemical Factory "Police" (Poland). The crude TiO2 was calcinated in air for 1-4h at the temperatures ranging from 600 to 800°C. The BET specific surface area of TiO2 decreased gradually with increasing the calcination temperature. The crude TiO2 exhibited specific surface area of 277 m2/g. In case of the catalysts heated at 600, 700 and 800°C the BET surface area amounted to 62.3-53.3, 33.4-26.8 and 8.9-8.3 m2/g, for the calcination time of 1-4h, respectively. The crystallite size of anatase increased with increasing heat treatment temperature and ranged from 19 to 53 nm, for the temperatures of 600-800°C, respectively. The catalysts annealed at 600 and 700°C contained primarily anatase phase (94-97%), whereas the photocatalysts heated at 800°C were composed mainly of rutile (97-99%). The highest effectiveness of azo dyes degradation was obtained in case of the photocatalyst calcinated for 1h at 700°C. The photocatalyst was composed mainly of anatase (97%) with crystallite size of 27 nm. The most effectively photodegraded was AR18, having the molecular weight of 640.4 g/mol. The most difficult to degrade was AY36 exhibiting the lowest molecular weight from all the dyes used (375.4 g/mol).

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Synthesis and structural analysis of Ni0.45Cu0.55Mn2O4 by Williamson–Hall and size–strain plot methods

Abstract

This paper describes synthesis and structural properties of Ni0.45Cu0.55Mn2O4 nanopowder, obtained by co-precipitation route. XRD pattern reveals cubic structure with lattice parameter 8.305 Å. We report crystallite size (D), micro strain (ε), dislocation density (ρD), and hopping lengths (LA and LB). We also report preferential orientation by texture coefficients [Tc (h k l)]. The Williamson-Hall plot and stress-strain plot also employed to understand the mechanical properties of materials.

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Catalyst free growth of single-crystalline bismuth nanorods by closed space sublimation technique

Abstract

In the present study, bismuth (Bi) thin films having thickness of 335 nm have been deposited onto a glass substrate by closed space sublimation (CSS) technique. Besides this, spontaneous growth of Bi nanorods has also been investigated for the first time, without template and catalyst assistance in a substrate temperature range of 380 to 430 °C using CSS technique. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were employed to investigate microstructure, morphology and roughness of the Bi nanorods. The diameter and length ranges of Bi nanorods were 80 to 400 nm and 3 to 5 μm, respectively. Moreover, they exhibited a rhombohedral structure with a dominant peak indexed at (012), (104), and (110). The mass percentage of Bi, determined by energy dispersive X-ray (EDX), was 99.93 %. The studies of electrical resistivity, Hall coefficient, magnetoresistivity, hole mobility and carrier concentration of Bi thin films were performed at 300 to 350 K and the electrical properties were found to be a function of temperature. The basic aim was to investigate the spectacular evolution of Bi nanostructures on as-deposited thin films and effects of thickness on their structural, electrical and dielectric properties. Detailed examination of SEM micrographs eliminated all other growth modes except self-catalytic tip growth by Vapor-Solid (VS) growth process which is believed to provide the driving force for spontaneous nanorod growth at high substrate temperature. Deposition of thinner Bi films provided a new possibility for fabrication of Bi nanorods of high quality.

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Effect of pH and annealing temperature on the structural and magnetic properties of cerium-substituted yttrium iron garnet powders produced by the sol-gel method

saturation magnetization of the garnet powder annealed at 1400 °C was M s = 24.5 emu/g. One feature of garnet powders is that the crystallite size influences the magnetic properties. To evaluate the magnetic properties of the garnet powders as a function of crystallite size, their sizes were calculated using the XRD results. The crystallite sizes ranged from 38 nm to 55 nm. The crystallite sizes increased as the annealing temperature increased from 800 °C to 1400 °C because of increased nucleation, and the crystallization of the samples was completed as shown in Fig. 1

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Effect of NaOH concentration on optical properties of zinc oxide nanoparticles

different NaOH concentrations (the inset shows variation of peak width and position of (1 0 1) peak with respect to NaOH concentration), (b) Uniform Deformation Model (UDM) of as-prepared ZnO nanoparticles using Williamson-Hall analysis (Tables show linear fit equation of the corresponding sample), (c) variation of crystallite size of as-prepared ZnO nanoparticles with respect to molar ratio. 3.2 Field emission scanning electron microscope (FE-SEM) analysis Field emission scanning electron microscopy (FE-SEM) images, shown in Fig. 2 , show the morphology

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Synthesis, investigation on structural and electrical properties of cobalt doped Mn–Zn ferrite nanocrystalline powders

concentration in the Mn–Zn ferrite. The peak position was found to shift towards higher diffraction angles due to the smaller ionic radius of cobalt (0.938 Å) compared to Mn and Zn radius. Fig. 2 X-ray diffraction patterns for Co x Mn y Zn y Fe 2 O 4 with (a) x = 0.1, y = 0.45 (b) x = 0.5, y = 0.25 and (c) x = 0.9, y = 0.05. Fig. 3 The magnified XRD patterns of Co x Mn y Zn y Fe 2 O 4 (x = 0.1, 0.5, 0.9 and y = 0.45, 0.25, 0.05) nanopowders in the range of 30° to 35°. XRD analysis can also be used to evaluate peak broadening with crystallite size

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Solvothermal synthesis and characterization of magnetic Fe3O4 nanoparticle by different sodium salt sources

water and ethanol, and dried at 70 °C in vacuum environment for 4 h. 2.3 Characterization Four available systems, XRF, XRD, SEM and FT-IR were used to characterize and compare the synthesized magnetite Fe 3 O 4 nanoparticles. XRD, Bruker D8 Advance diffractometer was used to collect XRD patterns at 30 kV and 20 mA, and CuKα radiation (λ = 0.1540598 nm). The particle sizes of synthesized nanoparticles were measured by FE-SEM (HITACHI S-4160). The crystallite size of the synthesized magnetic Fe 3 O 4 nanoparticles was estimated based on the Scherrer equation

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Studies on structural, optical and electrical properties of electron beam evaporated Cu2SnSe3 thin films

]. Fig. 1 (a) cubic sphalerite-like structure and (b) XRD pattern of as-deposited Cu 2 SnSe 3 thin film The average crystallite size of the CTSe film was calculated from Debye-Scherrer formula, D = 0.9λ/β cos θ, where λ is the wavelength of X-ray radiation, θ is the Bragg angle of the peak and β is the angular width of the full-width at half maximum (FWHM). Average crystallite size of the CTSe film was found to be 12 nm. This result is in close accordance with the earlier reports on nanoink coated CTSe films (15.5 nm) [ 9 ], whereas it is less than for

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