Journal of Metastable and Nanocrystalline Materials Vol. 40

Abstract: Nd³⁺ ion-doped ZnO nanomaterial was prepared using chemical synthesis method and its fluorescence spectra have been investigated at room temperature. From SEM images of the synthesized ZnO: Nd³⁺ nanoparticles it is observed that an increase in concentration of Nd³⁺ ions leading to the decrease in the particle size. Nearly hexagonal shapes for the dark spots in the SAED images indicate that the ZnO nanoparticles are almost hexagonal. The oscillator strengths leading to 4f ↔ 4f transitions are characterized by different Judd-Ofelt intensity parameters Ω_λ (λ = 2, 4 and 6). These Ω_λ parameters along with the fluorescence data and various radiative properties viz., spontaneous emission probability (A), radiative life time (t), fluorescence branching ratio (b) and stimulated emission cross-section (s_p) were evaluated and compared with the reported values. The values of these parameters indicate that the observed transitions ⁴F_3/2 → ⁴I_11/2, ⁴F_3/2 → ⁴I_13/2 and ⁴F_3/2 → ⁴I_15/2 can be considered to be good laser transitions in the near infrared region for different optoelectronic and spintronic uses.

Abstract: TiO₂ nanomaterial is a semiconductor material that exhibits promising photocatalysis activity. TiO₂ nanomaterials can be converted into several forms, including TiO₂ nanotubes, which have a larger surface area and more applications. In this study, TiO₂ nanotubes were synthesized hydrothermally using TiO₂ micro powder precursors. The synthesis involved two hydrothermal stages: the first to synthesize TiO₂ nanoparticles from TiO₂ micro powder precursors, and the second to synthesize TiO₂ nanotubes from TiO₂ nanoparticle precursors. TiO₂ micro powder was added to the synthesis of TiO₂ nanoparticles by hydrothermal at mole ratios of TiO₂/NaOH of 0.01, 0.025, and 0.04, respectively. The TiO₂ nanoparticles obtained exhibit a morphology in the form of short fibers, with particle sizes increasing as the mole ratios are added. Furthermore, they possess an anatase crystal structure at all mole ratios of TiO2/NaOH. Subsequently, the TiO₂ nanoparticles are calcined at 450°C. The results of the TiO2 nanoparticle calcination show that the morphology is in the form of short fibers, which are smaller than those of the uncalcinated sample. The calcinated sample also has larger particle sizes and an anatase crystal structure, compared to the uncalcinated sample. The TiO₂ nanotubes obtained exhibit an elongated tube morphology with outer diameters ranging from 3.93 to 11.44 nm, inner diameters ranging from 2.5 to 4.25 nm, and a wall thickness of 1.09 to 3.4 nm. The surface area of the TiO2 nanotubes is 256.744 m²/g.

Abstract: In this work, we have developed Cu-Fe alloys with a nanometric structure through the process of mechanosynthesis. We then followed the formation mechanism of these alloys and proceeded with a crucial step, which is cold compaction. We have elaborated Cu-Fe alloys with a nanometric structure by mechanosynthesis and following the mechanism of formation of these alloys, the we employed various analytical techniques to characterize the structural and microstructural properties of our powders. The X-ray diffraction method (XRD) was used to calculate the structural parameters, while laser granulometry was employed to study the evolution of particle size. Scanning electron microscopy (SEM) was then utilized to examine the morphology of the powders. Additionally, we investigated the electrochemical behavior of our alloys, focusing on their corrosion resistance. Electrochemical impedance spectroscopy (EIS) was performed in the frequency range of 10 kHz to 15 mHz to evaluate the corrosion performance.

Abstract: The corrosion product so-called black powder forms inside gas pipelines and negatively affects gas pipelines during the flow of gas therefore it needs continuous follow-up, collecting, and regular maintenance, to understand its physical characteristics and its nature is necessary for field operators to select the appropriate separation technique and to understand the possible roots causing the formation, there are certainly nanoparticles in the form of a large portion due to the effect of heat and moisture. The purpose of present work is to spot the light on black powder produced in gas pipelines by identifying the organic deposit around it, determining the percentage of deposit, determining the kinetic parameter, and thermodynamic parameters by utilizing TGA. Identification of metal power has been achieved by RDX. The black powder was subjected to three identifications first FTIR was to get clear information about the nature of the powder. It showed that the major was organic sulfurs and aromatic hydrocarbons deposited on the outer surface, XRD identified the kinds of iron oxides of iron oxide Fe₂O₃, and hydrated iron oxide FeOOH that formed mainly due to water condensate at dew point and water of periodical upsets, third TGA and DTG to determine the kinetics, and thermodynamics parameters and the percentages of organic hydrocarbons deposited on the outer surface of black powder by using Coats-Redfern at different heating rates including (10, 15, 20, and 25) Cº/min by using the flow rate 20 ml/min of helium as an inert gas, Activation energy increased 28.226-26.214 kJ/mole within the heating rate of 10-20 C^o/min, and entropy showed a decrease -281.749 to -279.66 J/Kmol, and enthalpy showed the same trend.

Abstract: The current work concerns preparing cobalt manganese ferrite (Co_0.2Mn_0.8Fe₂O₄) and decorating it with polyaniline (PAni) for supercapacitor applications. The X-ray diffraction findings (XRD) manifested a broad peak of PAni and a cubic structure of cobalt manganese ferrite with crystal sizes between 21 nm. The pictures were taken with a field emission scanning electron microscope (FE-SEM), which evidenced that the PAni has nanofibers (NF_s) structures, grain size 33 – 55 nm, according to the method of preparation, where the hydrothermal method was used. The magnetic measurements (VSM) that were conducted at room temperature showed that the samples had definite magnetic properties. Additionally, it was noted that the saturation magnetization value of PAni/Co_0.2Mn_0.8Fe₂O₄ nanocomposite and Co_0.2Mn_0.8Fe₂O₄ nanoparticles are maximum saturation magnetization values of (4.7) and (9) emu g⁻¹ respectively. Studying properties of electrochemical which were tested in 1 M of H₂SO₄ by using the CV cyclic voltammetry analysis, galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS), found the highest capacitance is 596 F/g.