Project description:Amorphous materials with non-periodic structures are commonly evaluated based on their chemical composition, which is not always the best parameter to evaluate physical properties, and an alternative parameter more suitable for performance evaluation must be considered. Herein, we quantified various structural and physical properties of Ce-doped strontium borate glasses and studied their correlations by principal component analysis. We found that the density-driven molar volume is suitable for the evaluation of structural data, while chemical composition is better for the evaluation of optical and luminescent data. Furthermore, the borate-rich glasses exhibited a stronger luminescence due to Ce3+, indicating a higher fraction of BO3/2 ring and larger cavity. Moreover, the internal quantum efficiency was found to originate from the local coordination states of the Ce3+ centres, independent of composition or molar volume. The comparison of numerical data of the matrix is useful not only for ensuring the homogenous doping of amorphous materials by activators, but also for determining the origin of physical properties.
Project description:New glass compositions containing high concentrations of Tb3+ ions were developed aiming at the production of magneto-optical (MO) fibers. This work reports on the structural and MO properties of a new glass composition based on (100 - x)(41GeO2-25B2O3-4Al2O3-10Na2O-20BaO) - xTb4O7. Morphological analysis (HR-TEM) of the sample with the highest concentration of Tb3+ ions confirmed the homogeneous distribution of Tb3+ ions and the absence of nanoclusters. All the samples presented excellent thermal stability against crystallization (ΔT > 100 °C). An optical fiber was manufactured by a fiber drawing process. The UV-Vis spectra of the glasses showed Tb3+ electronic transitions and optical windows varying from 0.4 to 1.6 μm. The magneto-optical properties and the paramagnetic behaviors of the glasses were investigated using Faraday rotation experiments. The Verdet constant (VB) values were calculated at 500, 650, 880, 1050, 1330, and 1550 nm. The maximum VB values obtained at 650 and 1550 nm for the glass with x = 18 mol% were -128 and - 17.6 rad T-1 m-1, respectively. The VB values at 500 and 1550 nm for the optical fiber containing 8 mol% of Tb4O7 were - 110.2 and - 9.5 rad T-1 m-1, respectively, while the optical loss at around 880 nm was 6.4 dB m-1.
Project description:The paper presents sorption behavior of Arachis hypogaea shells towards silver ions and possibility of their use as antimicrobial product. During the modification process of the natural sorbent, equilibrium tests were carried out. Moreover, the possibility of obtaining biocomposite Arachis hypogaea shells/nAg has been determined, and its antimicrobial properties have been evaluated. Additionally, sorption kinetics has been calculated. In the last step, silver ions were desorbed. The conducted equilibrium tests allowed to adjust the sorption isotherm model and determine the sorption capacity of tested material. This process is best described by Freudlich's isotherm, and the sorption capacity is equal to 12.33 mg/g. On the basis of kinetic studies, the chemical nature of this process has been proved (by choosing a pseudo-second order model for the sorption process). It has been confirmed that the obtained peanut shells modified with silver ions have antimicrobial properties. The tests allowed to obtain 100% inhibition of Aspergillus niger and ~?98% Escherichia coli.
Project description:Ce(3+)-doped yttrium aluminum garnet (YAG:Ce) nanocrystals were successfully synthesized via a facile sol-gel method. Multiple characterization techniques were employed to study the structure, morphology, composition and photoluminescence properties of YAG:Ce nanophosphors. The YAG:Ce0.0055 sintered at 1030?°C exhibited a typical 5d(1)-4f(1) emission band with the maximum peak located at 525?nm, and owned a short fluorescence lifetime ?1 (~28?ns) and a long fluorescence lifetime ?2 (~94?ns). Calcination temperature and Ce(3+) doping concentration have significant effects on the photoluminescence properties of the YAG:Ce nanophosphors. The emission intensity was enhanced as the calcination temperature increased from 830 to 1030?°C, but decreased dramatically with the increase of Ce(3+) doping concentration from 0.55 to 5.50 at.% due to the concentration quenching. By optimizing the synthesized condition, the strongest photoluminescence emission intensity was achieved at 1030?°C with Ce(3+) concentration of 0.55 at.%.
Project description:Hollow noble metal nanoparticles have excellent performance not only in surface catalysis but also in optics. In this work, the hollow Au-Ag alloy nanorices are fabricated by the galvanic replacement reaction. The dark-field spectrum points out that there is a big difference in the optical properties between the pure Ag nanorices and the hollow alloy nanorices that exhibit highly tunable localized surface plasmon resonances (LSPR) and that possess larger radiative damping, which is also indicated by the finite element method. Furthermore, the surface enhanced Raman scattering (SERS) and oxidation test indicate that hollow Au-Ag alloy nanorices show good anti-oxidation and have broad application prospects in surface-plasmon-related fields.
Project description:The reactions of the cyclo-As5 complex [Cp*Fe(η5 -As5 )] (B) with the AgI and CuI salts of the weakly coordinating anion (WCA) [FAl{OC6 F10 (C6 F5 )}3 ]- ([FAl]- ) are studied. These reactions allow the synthesis of the mononuclear complexes [M(η5 : η2 -B)2 ][FAl] (M=Ag (1), Cu (2)) when a ratio of B/M(FAl) 2 : 1 is used. Compound 1 shows an unusual disorder of the central AgI cation between two π-coordinating cyclo-As5 ligands, which is absent in 2 pointing to a weak interaction of the Ag center towards the cyclo-As5 ligands in B. When the ratio of B/Ag(FAl) is changed to 3 : 1 or 1 : 1, the respective coordination compounds [Ag(η2 -B)3 ][FAl] (3) and [Ag2 (η2 : η2 -B)2 ][FAl]2 (4) are accessible. The coordination modes of the cyclo-As5 units in 1, 3 and 4 are all different, reflecting the adaptive coordination behavior of B towards AgI ions. The optimized geometries in the gas phase of 1-4 are determined by DFT calculations to support the bonding situation observed in their solid-state structures.
Project description:A novel and effective method to improve scintillation properties of glass-ceramics, such as intensity enhancement and decay-time shortening, is reported in this work. Compared with crystal scintillators, glass scintillators always have the problems of low efficiency and long decay; how to solve them has always been a scientific puzzle in the field of scintillation glass-ceramics. The plasma enhancement effect can be predicted to solve the above problems. Ag+ ions were diffused into glasses by ion exchange, and then Ag nanoparticles and CsPbBr3 quantum dots were formed by heat treatment. The structure of the CsPbBr3 perovskite consists of a series of shared corner PbBr6 octahedra with Cs ions occupying the cuboctahedral cavities. By using Ag and the plasma resonance effect, the photoluminescence intensity of CsPbBr3 quantum dot glasses was enhanced by 3 times, its radioluminescence intensity increased by 6.25 times, and its decay time was reduced by a factor of more than one. Moreover, the mechanism of photoluminescence and radioluminescence enhanced by Ag and plasma was discussed based on the experimental results and finite-difference time-domain method. We concluded that the increase in radioluminescence intensity was related to plasma enhancements and the energy exchange between Ag nanoclusters and CsPbBr3 quantum dots. Doping Ag is a valid means to improve the scintillation luminescence of CsPbBr3 quantum dot glasses, which can be applied in the field of scintillation.
Project description:With the advancement of ultra-fast and high-energy pulsed laser output, lasers have caused serious harm to precision instruments and human eyes. Therefore, the development of optical limiting materials with a fast response, low optical limiting threshold, and high damage threshold are important. In this work, for the first time, it is reported that phosphors Gd2O2S:Tb3+(GOS) displays exceptional functionality in laser protection. GOS with sizes of 11 μm, 1 μm, and 0.45 μm are prepared. Based on the optical limiting and Z-scan technology systems under 532 nm and 1064 nm nanosecond laser excitation, the nonlinear optical properties of GOS are investigated. It is found that GOS exhibits outstanding optical limiting properties. In addition, the optical limiting response of GOS is size-dependent. Concerning the largest particle size, GOS has the best nonlinear optical response, while the precursor shows no nonlinear optical performance. Meanwhile, GOS doped gel glass also displays excellent optical limiting properties with high transmittance, which preliminarily validates the application of GOS and other scintillators in nonlinear optics and encourages more research to better realize the potential of GOS.
Project description:Yielding behavior in amorphous solids has been investigated in computer simulations using uniform and cyclic shear deformation. Recent results characterize yielding as a discontinuous transition, with the degree of annealing of glasses being a significant parameter. Under uniform shear, discontinuous changes in stresses at yielding occur in the high annealing regime, separated from the poor annealing regime in which yielding is gradual. In cyclic shear simulations, relatively poorly annealed glasses become progressively better annealed as the yielding point is approached, with a relatively modest but clear discontinuous change at yielding. To understand better the role of annealing on yielding characteristics, we perform athermal quasistatic cyclic shear simulations of glasses prepared with a wide range of annealing in two qualitatively different systems-a model of silica (a network glass) and an atomic binary mixture glass. Two strikingly different regimes of behavior emerge. Energies of poorly annealed samples evolve toward a unique threshold energy as the strain amplitude increases, before yielding takes place. Well-annealed samples, in contrast, show no significant energy change with strain amplitude until they yield, accompanied by discontinuous energy changes that increase with the degree of annealing. Significantly, the threshold energy for both systems corresponds to dynamical cross-over temperatures associated with changes in the character of the energy landscape sampled by glass-forming liquids.
Project description:It is critical to design a novel and simple bifunctional sensor for the selective and sensitive detection of ions in an aqueous media in environmental samples. As a result, in this study, tetraphenylethene hydrazinecarbothioamide (TPE-PVA), known as probe 1, was successfully synthesized and characterized as having impressive photophysical phenomena such as aggregation-induced emission (AIE) and mechanochromic properties by applying mechanical force to the solid of probe 1. The emission of the solid of probe 1 changed from turquoise blue to lemon yellow after grinding, from lemon yellow to parakeet green after annealing at 160 °C, and to arctic blue after fuming with DCM. Such characteristics could lead to a variety of applications in several fields. The probe was implemented and demonstrated remarkable selectivity and sensitivity toward mercury(II) and silver(I) ions by substantially switching off emission over other cations. Following an extensive photophysical analysis, it was discovered that detection limits (LOD) as low as 0.18344 and 0.2384 μg mL-1 for Hg2+ and Ag+, respectively, are possible with a quantum yield (Φ) of 2.26. Probe 1 was also explored as a Hg2+ and Ag+ paper strip-based sensor and kit for practical use. The binding mechanisms of probe 1 (TPE-PVA) with Hg2+ and Ag+ were confirmed by 1H NMR titration. These results could lead to the development of reliable onsite Hg2+ and Ag+ fluorescent probes in the future.