PEO/PVA blends have been prepared to investigate the effect of gamma rays on the structural, morphological and photoluminescence properties. The studies of non-irradiated and irradiated samples with ...radiation doses of 10 kGy were examined by using XRD, ATR-FTIR, Optical microscopy and PL. Gamma photons induced important chemical rearrangements, especially by PVA hydroxyl groups. We found that the crystallinity rate is strongly influenced by radiation. In this context, one could predict that the immiscibility of PVA with PEO and the interactions between the chains are of the electrostatic type. A structural-scale disturbance due to the radical formation leads to spherulitic texture modifications of the PEO. Due to the luminescence properties, the blend samples behave like core-shell nanoparticles. This phenomenon is due to the fact that the PVA polymer played the role of shell. Irradiation makes it possible to obtain well-ordered spherulites and to get a high pore density. The irradiated blend showed a higher quantum yield. The significant chemical and morphological changes caused by gamma radiation favored the optical recombination of hydroxyl groups.
A conceptual design for a handheld X‐ray diffraction (HHXRD) instrument is proposed. Central to the design is the application of energy‐dispersive XRD (EDXRD) in a back‐reflection geometry. This ...technique brings unique advantages which enable a handheld instrument format, most notably, insensitivity to sample morphology and to the precise sample position relative to the instrument. For fine‐grained samples, including many geological specimens and the majority of common alloys, these characteristics negate sample preparation requirements. A prototype HHXRD device has been developed by minor modification of a handheld X‐ray fluorescence instrument, and the performance of the prototype has been tested with samples relevant to mining/quarrying and with an extensive range of metal samples. It is shown, for example, that the mineralogical composition of iron‐ore samples can be approximately quantified. In metals analysis, identification and quantification of the major phases have been demonstrated, along with extraction of lattice parameters. Texture analysis is also possible and a simple example for a phosphor bronze sample is presented. Instrument formats other than handheld are possible and online process control in metals production is a promising area. The prototype instrument requires extended measurement times but it is argued that a purpose‐designed instrument can achieve data‐acquisition times below one minute. HHXRD based on back‐reflection EDXRD is limited by the low resolution of diffraction peaks and interference by overlapping fluorescence peaks and, for these reasons, cannot serve as a general‐purpose XRD tool. However, the advantages of in situ, nondestructive and rapid measurement, tolerance of irregular surfaces, and no sample preparation requirement in many cases are potentially transformative. For targeted applications in which the analysis meets commercially relevant performance criteria, HHXRD could become the method of choice through sheer speed and convenience.
Energy‐dispersive X‐ray diffraction implemented in a back‐reflection geometry has unique characteristics, particularly its insensitivity to sample morphology. The potential to develop a handheld X‐ray diffraction instrument based on this technique is explored with the help of a prototype instrument adapted from a handheld X‐ray fluorescence device.
•Materials studied lie in the Na3/4(Mn-Al-Ni)O2 pseudo-ternary system.•P3/P2 phase fraction was manipulated by adjusting the calcination temperature.•Superior electrochemical performance of P3/P2 ...biphasic cathodes.•Absence of the P3 to O3 phase in the Al-substituted P3-type compounds.
Layered oxide cathodes, a promising avenue for Na-ion batteries, hold the highest potential for commercialization. Herein, we delve into the structural and electrochemical properties of Al-substituted layered oxides in our quest to pinpoint the optimal cathode composition in the Na3/4(Mn-Al-Ni)O2 pseudo-ternary system. The cathode materials investigated were synthesized in three distinct phase configurations, which include two monophasic configurations with P3 and P2-type structures and a third biphasic cathode with equal proportions of P3 and P2 phases. The fractions of the P3 and P2 type phases in the cathode materials were manipulated by adjusting the calcination temperature. The varying concentration of Mn3+ and Mn4+, confirmed by X-ray photoelectron spectroscopy, was found to impact the cyclic stability of these materials significantly. During electrochemical testing, the P3 cathodes showed impressive rate performance and exhibited an excellent specific capacity of 195 mAh g−1 at 0.1C. Regarding cyclic performance, the biphasic cathodes consistently outperformed their monophasic counterparts, with P3/P2-Na0.75Mn0.50Ni0.25Al0.25O2 exhibiting 82 % capacity retention after 300 cycles. Analysis of operando Synchrotron XRD data revealed an absence of P3 to O3 type phase transition in the cathodes even at low voltages where large structural variations to the unit cell structure were observed. The absence of P3 to O3 transformations and the superior electrochemical performance of Na0.75Mn0.50Ni0.25Al0.25O2 underlines the importance of Al substitution and P3/P2 biphasic structure in enhancing the electrochemical performance of layered oxides.
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•Asphaltene of Azerbaijani oil is dominated by molecules with island architecture.•Vanadium porphyrin dominates in the asphaltene of Zagli oil.•Asphaltene molecule is thermostable up ...to 406 °C.
The lack of information about the chemical composition and structure of asphaltenes in crude oil, which has a sufficient share in the economy of Azerbaijan, complicates its processing and use. As a first attempt, this research is devoted to the detailed analysis of the average molecular structure and properties of asphaltenes isolated from crude oil samples collected from the Zaglı oil field using the integrated application of high-sensitivity devices such as Nuclear Magnetic Resonance (NMR), Ultraviolet–Visible (UV–Vis), Fourier Transform Infrared (FTIR) spectroscopy, X-ray diffraction analysis, Elemental analysis, Scanning Electron Microscope (SEM), Differential Thermal Analysis (DTA), Dynamic Light Scattering (DLS). The average molecular formula of asphaltene monomer was determined to be C49.5H55O3.04N0.95S2. An island architecture with one polycyclic aromatic hydrocarbon (PAH) in each molecule of this compound is predominant. Amorphous asphaltene molecule contains vanadium-based porphyrins, –COOH group, disulfide (−S-S-) linkage. It was found that asphaltene of crude oil is stable up to 406 °C. The three-stage pyrolysis process in the temperature range of 406–818 °C resulted in the formation of 12.58 % coke. Due to the absence of free radicals in the range of 25–100 ℃, the asphaltene sample is dielectric. The decrease of monodispersity with particle growth in asphaltene compound in different solvents was analyzed by dynamic and static light scattering. The HOMO-LUMO energy gap of the asphaltene molecule was 2.666 eV, indicating high stability. The knowledge gained about the chemical composition and molecular structure of asphaltenes can help prevent problems arising in oil production and refining processes.
The PL emission and excitation spectrum of prepared Ca2Pb3(PO4)3Cl:Ce3+ phosphor explained in which excitation at wavelength of 331 nm and it prepared by combustion synthesis method for the emission ...spectrum exhibits a well defined asymmetric band with maximum at 443 nm emitting a blue light give isolated blue emission at 443 nm for 10 mol %, which has higher PL emission concentrations. The samples were characterized by XRD, SEM, PL and CIE color co-ordinates techniques with relation of emission intensity w.r.to. concentrations of rare earth ion. This process enables quick and energy-efficient generation of well-crystallized particles in fine powder form within a little action. The emission spectra are clearly from the same observable site. No another emission band was observed in emission spectrum indicating that trivalent cerium ion occupies one category of sites in the host material.
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