Applied Science Private University

About: Applied Science Private University is a education organization based out in Amman, Jordan. It is known for research contribution in the topics: Population & Catalysis. The organization has 4124 authors who have published 5299 publications receiving 116167 citations.

Reduced thermal degradation of the red-emitting Sr2Si5N8:Eu2+ phosphor via thermal treatment in nitrogen

Abstract: The red phosphor of Sr2Si5N8:Eu2+ was synthesized by a solid state reaction. The as-synthesized phosphor powders were post-treated in a N2 atmosphere. The prepared samples were analyzed by XRD, FE-SEM, TG-DTA, FT-IR, zeta potential, cathodoluminescence (CL), photoluminescence (PL), quantum efficiencies (QEs), and temperature-dependent PL and QE techniques. After the thermal treatment in N2, it was found that the N2-treatment caused a negligible influence on the phase purity and particle morphology; the surface of the phosphor particle became more hydrophilic; the isoelectric point (IEP) of the suspension containing phosphor powder shifted to a higher pH value; the edge area (formed surface layer) of the phosphor particle had lower CL intensity than the inner part but it inhibited the surface damage caused by e-beam irradiation; more significantly, the formed surface layer plays a passivating role in preventing the Eu2+ activator from being oxidized, consequently, effectively reducing thermal degradation that deteriorates the PL intensity of the Sr2Si5N8:Eu2+ phosphor.

13C NMR Spectroscopy of a Novel Amine Species in the DEAB–CO2–H2O system: VLE Model

Abstract: In the present work, ion speciation studies in solutions of the novel amine 4-(diethylamine)-2-butanol (DEAB), at various CO2 loadings (0–0.8 mol of CO2/mol of amine) and amine concentrations (0.52–1.97 M), were determined by 13C nuclear magnetic resonance (NMR) spectroscopy. In addition, the dissociation constant K of DEABH+ was determined at 24.5, 35, and 45 °C using a pH meter. The ion speciation plot, which contains various sets of concentrations of DEAB, protonated DEAB, bicarbonate, and carbonate, was successfully generated. Because DEAB is a novel solvent, this is the first time that the ion speciation plots of the DEAB–CO2–H2O system have been developed. It is also the first time that the 13C NMR calibration technique was applied to develop the vapor–liquid equilibrium (VLE) model for an amine–CO2–H2O system. The results obtained from the present work can be a great help for the further analysis of the DEAB VLE model, as well as CO2 absorption and kinetics studies. Furthermore, it was found that t...