Optical properties of antimony-borate glass rods co-doped with Eu3+/Ag+ ions

This paper presents the results of research on the luminescent properties of antimony-borate glass rods doped with europium and silver ions. The reduction of silver ions to the form of nanoparticles was carried out and the occurrence of localized plasmon resonance was demonstrated, which caused changes in the Eu3+ luminescence signal at a wavelength of 613 nm. The effect of the concentration of silver ions dopant at a constant content of europium ions on the luminescence and absorption characteristics of the produced samples was investigated. In the examined doping range, no large dependencies of spectral changes as a function of the concentration of silver ions were found. A clear quenching of the luminescence was observed due to the heating time of the doped glass matrices for the energy transition (5D0 → 7F2). Full Text: PDF ReferencesS. Kuzman, J. Perisa, V. Dordevic, I. Zekovic, I. Vukoje, Z. Antic and M. D. Dramicanin, "Surface Plasmon Enhancement of Eu3+ Emission Intensity in LaPO4/Ag Nanoparticles", Materials 13, 3071 (2020). CrossRef V.P. Prakashan, M.S. Sajna, G. Gejo, M.S. Sanu, A.C. Saritha, P.R. Biju, J. Cyriac and N.V. Unnikrishan, "Surface Plasmon Assisted Luminescence Enhancement of Ag NP/NWs-Doped SiO2-TiO2-ZrO2:Eu3+ Ternary System", Plasmonics 14, 673 (2019). CrossRef O. Malta, P. Santa-Cruz, G. Sa and F. Auzel, "Fluorescence enhancement induced by the presence of small silver particles in Eu3+ doped materials", J. Lumin., 33, 261 (1985). CrossRef O. Malta, P. Santa-Cruz, G. Sa and F. Auzel, "Time evolution of the decay of the 5Do level of Eu3+ in glass materials doped with small silver particles", Chem. Phys. Lett, 116, 396 (1985). CrossRef J. Zmojda, M. Kochanowicz, P. Miluski et al., "The influence of Ag content and annealing time on structural and optical properties of SGS antimony-germanate glass doped with Er3+ ions", Journal of Molecular Structure 1160, 428 (2018). CrossRef Ki Young Kim, Plasmonics: Principles and Applications (Croatia, InTechOpen 2012) CrossRef M.R. Dousti, M.R. Sahar, S.K. Ghoshal et al., "Up-conversion enhancement in Er3 +-Ag co-doped zinc tellurite glass: Effect of heat treatment", Journal of Non-Crystalline Solids 358, 2939 (2012). CrossRef I. Soltani, S. Hraiech, K. Horchani-Naifer et al., "Effect of silver nanoparticles on spectroscopic properties of Er3+ doped phosphate glass", Optical Materials 46, 454 (2015). CrossRef R. Schneider, E.A. de Campos, J.B.S. Mendes, J.F. Felix, P.A. Santa-Cruz, "Lead–germanate glasses: an easy growth process for silver nanoparticles and their promising applications in photonics and catalysis", RSC Advances 7 (66), 41479 (2017). CrossRef

Enhanced water durability of phosphor-in-glass (PiG) basing on SnCl2–P2O5 glass matrix induced by adding ZnO

Phosphor-in-glass (PiG) composed of glass matrix and the embedded phosphor particles has been intensively developed to meet the requirement of high-power LED lighting sources. P2O5-based glass matrices are the promising candidates to fabricate high luminescence PiG in view of their low-melting temperature to avoid the erosion of phosphor by glass melting, however, their poor chemical durability limited the practical application. In this work, the water durability of PiG basing on SnCl2–P2O5–ZnO glass matrix embedded with YAG: Ce[Formula: see text] phosphor is demonstrated. With the addition of ZnO, the water durability of SnCl2–P2O5- based PiG is enhanced significantly without obvious loss of light output. The influence of ZnO addition with variable contents on the microstructure, photoluminescent properties and the water durability of the obtained PiG is investigated through a series of characterizations. The obvious improvement of the water erosion resistance induced by adding ZnO provides an optional route to develop higher stability, lead-free, cost-effective low-melting point P2O5-based glass matrix for fabrication of high performance PiG materials.

Feasibility study of fluorescent lamp waste recycling by thermal desorption

The proposed Minamata Convention ban on the use of fluorescent lamps at the end of 2020, with a consequent reduction in mercury (Hg) light products, is expected to produce large amounts of discarded fluorescent bulbs. In this context, the most effective recycling options are a thermal mercury recovery system and/or aqueous solution leaching (lixiviation) to recover rare earth elements (REEs). Due to the heterogeneous nature of these wastes, a complete characterization of Hg compounds in addition to a determination of their desorption temperatures is required for their recycling. The objective of this study is to assess the feasibility of a fast cost-effective thermal characterization to ameliorate recycling treatments. A pyrolysis heating system with a heat ramping capability combined with atomic absorption spectrometry makes it possible to obtain residue data with regard to the temperature ranges needed to achieve total Hg desorption. The major drawback of these heat treatments has been the amount of Hg absorbed from the residue by the glass matrices, ranging from 23.4 to 39.1% in the samples studied. Meanwhile, it has been estimated that 70% of Hg is recovered at a temperature of 437 °C.

Photoinduced and Classical Sol-Gel Synthesis: Spectral and Photophysical Behavior of Silica Matrix Doped by Novel Fluorescent Dye Based on Boron Difluoride Complex

The boron difluoride complex is known as an extraordinary class of fluorescent dyes, which has attracted research interest because of its excellent properties. This article reports the optical properties such as absorption, fluorescence, molar absorptivity, and photo-physical parameters like dipole moment, and oscillator strength of new fluorescent organic dye based on boron difluoride complex 2-(1-(difluoroboraneyl)-1,2-dihydroquinolin-2-yl)-2-(1-methylquinoxalin-2-ylidene) acetonitrile (DBDMA). The spectral characterization of the dye was measured in sol-gel glass, photosol-gel, and organic–inorganic matrices. The absorption and fluorescence properties of DBDMA in sol-gel glass matrices were compared with each other. Compared with the classical sol-gel, it was noticed that the photosol-gel matrix is the best one with immobilized DBDMA. In the latter, a large stokes shift was obtained (97 nm) and a high fluorescence quantum yield of 0.5. Special attention was paid to the addition of gold NPs into the hybrid material. The fluorescence emission intensity of the DBDMA with and without gold nanoparticles in different solid media is described, and that displayed organic–inorganic matrix behavior is the best host.

Use of Terbium Doped Phosphate Glasses for High Dose Radiation Dosimetry—Thermoluminescence Characteristics, Dose Response and Optimization of Readout Method

The phosphate glass samples doped with Tb2O3 oxide (general formula: P2O5-Al2O3-Na2O-Tb2O3) were synthesized and studied for usage in high-dose radiation dosimetry (for example, in high-activity nuclear waste disposals). The influence of terbium concentration on thermoluminescent (TL) signals was analyzed. TL properties of glasses were investigated using various experimental techniques such as direct measurements of TL response vs. radiation dose, Tmax–Tstop and VHR (various heating rate) methods, and glow curve deconvolution analysis. The thermoluminescence dosimetry (TLD) technique was used as the main investigation tool to study detectors’ dose responses. It has been proved that increasing the concentration of terbium oxide in glass matrices significantly increases the thermoluminescence yield of examined material. For the highest dose range (up to 35 kGy), the dependence of the integrated thermoluminescent signals vs. dose can be considered as a saturation-type curve. Additional preheating of samples improves linearity of signal vs. dose dependencies and leads to a decrease of the signal loss over time. All obtained data suggest that investigated material can be used in high-dose radiation dosimetry. Additional advantages of the investigated dosimetric system are its potential ability to re-use the same dosimeters multiple times and the fact that reading dosimeters only requires usage of a basic TL reader without any modifications.

Transition Metals Doped Nanocrystals: Synthesis, Characterization, and Applications

Doping is a technique that makes it possible to incorporate substitutional ions into the crystalline structure of materials, generating exciting properties. This book chapter will comment on the transition metals (TM) doped nanocrystals (NCs) and how doping and concentration influence applications and biocompatibility. In the NCs doped with TM, there is a strong interaction of sp-d exchange between the NCs’ charge carriers and the unpaired electrons of the MT, generating new and exciting properties. These doped NCs can be nanopowders or be embedded in glass matrices, depending on the application of interest. Therefore, we show the group results of synthesis, characterization, and applications of iron or copper-doped ZnO nanopowders and chromium-doped Bi2S3, nickel-doped ZnTe, and manganese-doped CdTe quantum dots in the glass matrices.

Influence of Glass Composition on the Luminescence Mechanisms of CdSe Quantum Dot-Doped Glasses

<div> <div> <div> <p>In this work, we characterized the electronic structure of CdSe quantum dots embedded in a series of x Na2O, (1–x) SiO2 glass matrices (x = 0, 0.25, 0.33 and 0.5). We analyzed the impact of the glass matrix composition on both the atomic structure of the quantum dot (QD) and the QD/glass interface, as well as the luminescence mechanisms, using density functional theory (DFT) calculations. The increase of Na2O content in the glass matrices was found to promote the formation of Cd–O and Se–Na interfacial bonds, and disrupting the Cd–Se bonds network. In particular, we show that the glass composition directly affects the nature of the highest occupied molecular orbitals (HOMO). According to the atomic structure, the band gap distribution and the density of states calculation, we find that there is significant reconstruction of the QD, and that the picture sometimes proposed of a “pristine QD” surrounded by glass is not realistic. The introduction of CdSe QD significantly decreased the bandgap of the glass compared to pristine glasses, and the interfacial bonds greatly contributed to the frontier orbitals without forming midgap states. We propose a new energy diagram, quite different from the traditional model, to explain the luminescence of CdSe quantum dot- doped glasses, originating from the intrinsic emission of this hybrid system {QD + glass}. These results improve our understanding of the luminescence of CdSe quantum dot-doped glasses, explaining the reason for the poor quantum efficiency and broad emission linewidth compared with their colloidal counterparts. </p> </div> </div> </div>

Influence of Glass Composition on the Luminescence Mechanisms of CdSe Quantum Dot-Doped Glasses

<div> <div> <div> <p>In this work, we characterized the electronic structure of CdSe quantum dots embedded in a series of x Na2O, (1–x) SiO2 glass matrices (x = 0, 0.25, 0.33 and 0.5). We analyzed the impact of the glass matrix composition on both the atomic structure of the quantum dot (QD) and the QD/glass interface, as well as the luminescence mechanisms, using density functional theory (DFT) calculations. The increase of Na2O content in the glass matrices was found to promote the formation of Cd–O and Se–Na interfacial bonds, and disrupting the Cd–Se bonds network. In particular, we show that the glass composition directly affects the nature of the highest occupied molecular orbitals (HOMO). According to the atomic structure, the band gap distribution and the density of states calculation, we find that there is significant reconstruction of the QD, and that the picture sometimes proposed of a “pristine QD” surrounded by glass is not realistic. The introduction of CdSe QD significantly decreased the bandgap of the glass compared to pristine glasses, and the interfacial bonds greatly contributed to the frontier orbitals without forming midgap states. We propose a new energy diagram, quite different from the traditional model, to explain the luminescence of CdSe quantum dot- doped glasses, originating from the intrinsic emission of this hybrid system {QD + glass}. These results improve our understanding of the luminescence of CdSe quantum dot-doped glasses, explaining the reason for the poor quantum efficiency and broad emission linewidth compared with their colloidal counterparts. </p> </div> </div> </div>

Towards a Rationalization of Ultrafast Laser-Induced Crystallization in Lithium Niobium Borosilicate Glasses: The Key Role of The Scanning Speed

Femtosecond (fs)-laser direct writing is a powerful technique to enable a large variety of integrated photonic functions in glass materials. One possible way to achieve functionalization is through highly localized and controlled crystallization inside the glass volume, for example by precipitating nanocrystals with second-order susceptibility (frequency converters, optical modulators), and/or with larger refractive indices with respect to their glass matrices (graded index or diffractive lenses, waveguides, gratings). In this paper, this is achieved through fs-laser-induced crystallization of LiNbO3 nonlinear crystals inside two different glass matrices: a silicate (mol%: 33Li2O-33Nb2O5-34SiO2, labeled as LNS) and a borosilicate (mol%: 33Li2O-33Nb2O5-13SiO2-21B2O3, labeled as LNSB). More specifically, we investigate the effect of laser scanning speed on the crystallization kinetics, as it is a valuable parameter for glass laser processing. The impact of scanning energy and speed on the fabrication of oriented nanocrystals and nanogratings during fs-laser irradiation is studied.Fs-laser direct writing of crystallized lines in both LNS and LNSB glass is investigated using both optical and electron microscopy techniques. Among the main findings to highlight, we observed the possibility to maintain crystallization during scanning at speeds ~ 5 times higher in LNSB relative to LNS (up to ~ 600 µm/s in our experimental conditions). We found a speed regime where lines exhibited a large polarization-controlled retardance response (up to 200 nm in LNSB), which is attributed to the texturation of the crystal/glass phase separation with a low scattering level. These characteristics are regarded as assets for future elaboration methods and designs of photonic devices involving crystallization. Finally, by using temperature and irradiation time variations along the main laser parameters (pulse energy, pulse repetition rate, scanning speed), we propose an explanation on the origin of 1) crystallization limitation upon scanning speed, 2) laser track width variation with respect to scanning speed, and 3) narrowing of the nanogratings volume but not the heat-affected volume.