Synthesis and Investigation of Novel Optical Active SiO2 Glasses with Entrapped YAG:Ce Synthesized via Sol-Gel Method.

We present a crack-free optically active SiO2 glass-composite material containing YAG:Ce synthesized via a modified sol-gel technique. A glass-composite material consisting of yttrium aluminum garnet doped with Ce3+ (YAG:Ce) was entrapped into a SiO2 xerogel. This composite material was prepared using a sol-gel technique with modified gelation and a drying process to obtain crack-free optically active SiO2 glass. The concentration of the YAG:Ce was from 0.5 to 2.0 wt%. All synthesized samples were characterized via X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques, confirming their exceptional quality and structural integrity. The luminescence properties of the obtained materials were studied. Overall, the prepared samples' excellent structural and optical quality makes them great candidates for further investigation, or even potential practical application. Furthermore, boron-doped YAG:Ce glass was synthesized for the first time.

Enhanced optical properties of yttrium aluminum garnet with the yttrium vanadate impurity phase.

Yttrium aluminum garnet doped with europium with an additional impurity phase of yttrium vanadate doped europium has been prepared in different ways: synthesized by a sol-gel route and mechanically mixed in a mortar. The obtained samples were characterized by X-ray diffraction analysis, and scanning electron microscopy. Photoluminescence spectra were recorded to understand the role of the impurity phase in the garnet's optical properties. The impurity phase showed a significant contribution to the optical properties of Y3Al5O12:1%Eu.

Sustainable removal of anodized aluminum dye by groundwater treatment waste: experimental and modeling.

Groundwater treatment waste (GWTW), as an environmentally friendly renewable nanomaterial, was implemented for the removal of anodized aluminum dye Sanodure Green (SG) from aqueous solutions. The capability of the SG metal complex dye removal was assessed by measuring solution decoloration and chromium elimination degree. GWTW was characterized using FTIR, SEM, EDX, TEM, XPS and surface area measurements. Kinetic curves were obtained by changing initial dye concentration, pH, temperature and adsorbent dose. Kinetic studies showed that up to 90 % of SG dye was removed within a contact time of 20 min. The adsorption of the dye was favourable at 293 K temperature in the acidic pH region (pH 1.5-2.0) with maximum adsorption capacity 185 mg g-1. Langmuir-Freundlich isotherm model as well as hyperbolic tangent, diffusion-chemisorption and Elovich kinetic models accurately describe the dye removal process. The calculated thermodynamic parameters confirmed that SG dye removal occurred spontaneously and exothermically. The magnitude of enthalpy change (ΔH° = -35.80 kJ mol-1) was in agreement with the electrostatic interaction. The adsorption potential of GWTW for SG dye removal was also evaluated using a real wastewater produced after dyeing of anodized aluminum.

Temperature-Induced Structural Transformations in Undoped and Eu3+-Doped Ruddlesden-Popper Phases Sr2SnO4 and Sr3Sn2O7: Relation to the Impedance and Luminescence Behaviors.

We report that luminescence of Eu3+ ion incorporated into Ruddlesden-Popper phases allows monitoring phase transition in powders (instead of single crystals), in a time-efficient manner (compared to neutron diffraction), and importantly, with greater sensitivity than previous methods. Crystal structure and dielectric response of undoped and 0.5%Eu3+-doped Sr3Sn2O7 ceramics were studied as a function of temperature over the temperature range of 300-800 K. The luminescence studies of 0.5%Eu3+-doped Sr2SnO4 and Sr3Sn2O7 samples were performed in the temperature range of 80-500 K. These results were compared with the respective dependences for the undoped compounds. The structural transformations in 0.5%Eu3+-doped Sr3Sn2O7 were found at 390 and 740 K. The former is associated with the isostructural atomic rearrangement that resulted in a negative thermal expansion along two of three orthorhombic crystallographic axes, while the latter corresponds to the structural transition from the orthorhombic Amam phase to the tetragonal I4/mmm one. A similar temperature behavior with the structural transformations in the same temperature ranges was observed in undoped Sr3Sn2O7, although the values of lattice parameters of the Eu3+-doped and undoped compounds were found to be slightly different indicating an incorporation of europium in the crystal lattice. A dielectric anomaly associated with a structural phase transition was observed in Sr3Sn2O7 at 390 K. Optical measurements performed over a wide temperature range demonstrated a clear correlation between structural transformations in Eu3+-doped Sr2SnO4 and Sr3Sn2O7 and the temperature anomalies of their luminescence spectra, suggesting the efficacy of this method for the determination of subtle phase transformations.