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Study of Polymorphism of Borovanadate Glass of Sodium by Raman Spectroscopy Low Frequencies
摘要： Sodium tetraborate (100 – x)(Na2B4O7.10H2O) – xV2O5, (x = 0 to 20 mole %) has been elaborated by splat cooling technique. Raman Measurements on the doped and non polish samples reveal the presence of the of α-NaVO3 crystal on the superficial layer. After polishing, Raman spectra characteristic of glasses are obtained with two main bands located at 555 and 1097 cm-1 in the undoped glass and four bands at 241, 381, 776 and 938 cm-1 for the vanadium oxyde doped glasses. The volume devitrification of these glasses occurs at 750° C and the β-NaVO3 crystalline phase is identified by Raman scattering.
关键词： Non-linear optics,Oxide glasses,XRD,Raman scattering,DSC
更新于2025-09-09 09:28:46
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Luminescence and energy transfer studies of Ce3+/Dy3+ doped fluorophosphate glasses
摘要： The fluorophosphate (PKABfNf:P2O5+K2O+Al2O3+BaF2+NaF2) glasses doped with single and co-doped (Ce and/or Dy) were prepared by conventional melt quenching technique and characterized their luminescence properties. The emission spectra of co-doped glass (PKABfNfCeDy) showed a broad blue band of Ce3+ ions combined with the sharp peaks of Dy3+ ions. Judd-Ofelt (JO) intensity parameters have been obtained from the optical absorption spectra of 1.0 mol % of Dy3+ (PKABfNfDy1.0) glass. JO theory has been used to find the radiative properties of PKABfNfDy1.0 glass by using Futchbauer-Ladenbergh formula. The (Ce3+/Dy3+) co-doped glass exhibit radiative energy transfer (ET) from Ce3+ to Dy3+ upon UV excitation and then intensity is increased with increase in Dy3+ ion concentration. The ET mechanism from Ce3+ to Dy3+ ion has been analyzed. The theoretical ET efficiency and quantum yield values were calculated from the emission spectrum of the Ce3+ and (Ce3+/Dy3+) co-doped glasses. These results suggest that the co-doped PKABfNfCeDy glasses are promising candidate for commercial white light applications.
关键词： W-LEDs,Dysprosium,Fluorophosphate glasses,Energy transfer,Judd-Ofelt analysis,Quantum yield,Cerium
更新于2025-09-09 09:28:46
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Solar glasses' provide power for devices
摘要： The dark lenses of sunglasses have been replaced with organic solar cells by scientists in Germany. The cells can power a small microcontroller that sends information on ambient conditions to displays in the spectacle arms, and in future might provide power for personal devices such as hearing aids.
关键词： power for devices,organic solar cells,solar glasses
更新于2025-09-09 09:28:46
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Comparative Spectroscopic Investigation of Tm3+:Tellurite Glasses for 2-μm Lasing Applications
摘要： We performed a comparative spectroscopic analysis on three novel Tm3+:tellurite-based glasses with the following compositions Tm2O3:TeO2-ZnO (TeZnTm), Tm2O3:TeO2-Nb2O5 (TeNbTm), and Tm3+:TeO2-K2O-Nb2O5 (TeNbKTm), primarily for 2-μm laser applications. Tellurite glasses were prepared at different doping concentrations in order to investigate the effect of Tm3+ ion concentration as well as host composition on the stimulated emission cross sections and the luminescence quantum efficiencies. By performing Judd–Ofelt analysis, we determined the average radiative lifetimes of the 3H4 level to be 2.55 ± 0.07 ms, 2.76 ± 0.03 ms and 2.57 ± 0.20 ms for the TeZnTm, TeNbTm and TeNbKTm samples, respectively. We clearly observed the effect of the cross-relaxation, which becomes significant at higher Tm2O3 concentrations, leading to the quenching of 1460-nm emission and enhancement of 1860-nm emission. Furthermore, with increasing Tm2O3 concentrations, we observed a decrease in the fluorescence lifetimes as a result of the onset of non-radiative decay. For the 3H4 level, the highest obtained quantum efficiency was 32% for the samples with the lowest Tm2O3 ion concentration. For the 1860-nm emission band, the average emission cross section was determined to measure around 6.33 ± 0.34 × 10?21 cm2, revealing the potential of thulium-doped tellurite gain media for 2-μm laser applications in bulk and fiber configurations.
关键词： thulium-doped laser glasses,solid-state spectroscopy,lanthanide ion-doped glasses,glass lasers,2-micron lasers,thulium,tellurite glass
更新于2025-09-04 15:30:14
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Physical Properties and Structural Studies of Lithium Borophosphate Glasses Containing TeO2
摘要： This work presents a study on the structure, thermal behavior and properties of (100-x)[0.5Li2O-0.1B2O3-0.4P2O5]-xTeO2 glasses prepared within the concentration range of x=0-80 mol% TeO2. The structure of the glasses was studied with a combined Raman, 31P and 11B MAS NMR spectroscopy. 31P MAS NMR and Raman spectrum of the pure 50Li2O-10B2O3-40P2O5 glass indicates the co-existence of Q2 and Q1 phosphate units in the glass structure. Raman spectra of TeO2 containing glasses revealed that TeO2 is incorporated in the structural network in the form of TeO3 and TeO4 (TeO3+1) units. The ratio of TeO4/TeO3 increases with rising TeO2 content. Apart from the formation of P-O-Te and Te-O-Te bonds, the formation of B-O-Te bonds in the form of mixed tetrahedral units B(OP)4-n(OTe)n also takes place as shown by 11B MAS NMR spectroscopy. The structural studies were correlated with the thermal behavior and physical properties of glasses (density, molar volume, chemical durability and refractive index). DSC studies showed that all glasses crystallize on heating within a temperature region of 400-550°C and the surface nucleation mechanism prevails over the internal one. The crystallization temperature decreases with increasing TeO2 content. The compounds formed by crystallization were LiPO3, Li4P2O7, BPO4 and α-TeO2. Glass transition temperature and dilatometric softening temperature, estimated from thermodilatometry curves, decrease with increasing TeO2 content, whereas the thermal expansion coefficient increases.
关键词： Phosphate Glasses,Tellurite Glasses,Properties,Structure
更新于2025-09-04 15:30:14
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Patient-reported outcomes of multifocal and accommodating intraocular lenses: analysis of 117 patients 2–10 years after surgery
摘要： The purpose of this study was to determine the satisfaction levels of patients at least 2 years after cataract surgery implantation with bilateral accommodating or bilateral multifocal intraocular lenses (IOLs) and to determine the relative rate of spectacle independence and adverse symptoms in that same time frame. Design: Patient questionnaire administered in a single-center private practice at least 2 years after cataract surgery with presbyopia-correcting IOL implantation. Methods: Patients who had undergone uncomplicated cataract surgery with an accommodating or multifocal IOL implant were eligible for inclusion. Patients with visually significant non-IOL-related postoperative morbidity were excluded. Patients with astigmatism or residual refractive error were not excluded. The main outcome measure was patient satisfaction at least 2 years after IOL implantation. Results: Sixty-eight patients who received accommodating lenses and 49 patients who received multifocal lenses completed the questionnaire. The mean age of all patients was 75.7 years at the time of survey; the mean number of years since cataract surgery was 5.4 years. Overall, there were no significant differences between the two groups or within each group between the different lenses used. About 90% of patients in each group were “very satisfied” or “somewhat satisfied” with their vision at least 2 years after the initial surgery. Conversely, only one in eleven patients found his vision to be worse than expected. Conclusions: The majority of patients who received either accommodating or multifocal IOLs remain satisfied with their lens of choice more than 5 years after the original surgery. Glare and halos remain more noticeable in patients who received multifocal lenses.
关键词： accommodating IOLs,presbyopia,Tecnis,satisfaction,intraocular lenses,crystalens,ReSTOR,patient-reported satisfaction,multifocal IOLs,glasses
更新于2025-09-04 15:30:14
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Investigation of the Atomic Structure of Ge-Sb-Se Chalcogenide Glasses
摘要： Glasses with composition of GexSb40-xSe60 (x= 40, 35, 32, 27, 20, 15 at. %) have been synthesized. Neutron and X-ray diffraction techniques were used to study the atomic glassy structure, and Reverse Monte Carlo (RMC) simulations were applied to model the 3-dimensional atomic configurations and thorough mapping of the atomic parameters, such as first and second neighbour distances, coordination numbers, and bond-angle distributions. The results are explained with formation of GeSe4 and SbSe3 structural units, which correlate with the Ge/Sb ratio. For all the studied compositions, the Ge-Se, Sb-Se, Ge-Ge, and Se-Se bonds are significant. RMC simulations reveal the presence of Ge-Sb and Sb-Sb bonds, being dependent on Ge/Sb ratio. All atomic compositions satisfy formal valence requirements, i.e., Ge is fourfold coordinated, Sb is threefold coordinated, and Se is twofold coordinated. By increasing the Sb content, both the Se-Ge-Se bonds angle of 107±3° and Se-Sb-Se bonds angle of 118±3° decrease, respectively, indicating distortion of the structural units. Far infrared Fourier Transform spectroscopic measurements conducted in the range of 50-450 cm-1 of oblique (75°) incidence radiation have revealed clear dependences of the IR band’s shift and intensity on the glassy composition, showing features around x=27 at.% supporting the topological phase transition to a stable rigid network consisting mainly of SbSe3 pyramidal and GeSe4 tetrahedral clusters. These results are in agreement with the Reverse Monte Carlo models, which define the Ge and Sb environment.
关键词： X-ray diffraction,chalcogenide glasses,atomic structure,FTIR spectroscopy,Ge-Sb-Se,neutron diffraction,Reverse Monte Carlo
更新于2025-09-04 15:30:14
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Correlation between the structure and structural relaxation data for (GeSe2)y(Sb2Se3)1-y glasses
摘要： Combined calorimetric and structural study, employing the techniques of differential scanning calorimetry and Raman spectroscopy, was performed to describe the enthalpy relaxation processes in the (GeSe2)y(Sb2Se3)1-y chalcogenide glasses. The full glass forming compositional region (y = 0.3–0.9) was explored. The enthalpy relaxation was described in terms of the phenomenological Tool-Narayanaswamy-Moynihan model. Compositional evolution of the glass transition temperatures and relaxation activation energies was explained based on the changing average bond energies and overall interconnectivity of the glassy matrices. Resemblance between the activation energies of the relaxation processes and viscous flow was confirmed for all studied glasses. Non-linearity and non-exponentiality of the enthalpy relaxation were found to be invariant with composition. The structural relaxation kinetics as well as kinetic fragilities determined for the present (GeSe2)y(Sb2Se3)1-y glassy system were very similar to the results obtained earlier for the (GeS2)y(Sb2S3)1-y glasses, which can be attributed to the similarly constrained topology of the pseudo-binary compositional lines.
关键词： Enthalpy relaxation,Raman spectroscopy,TNM model,Ge-Sb-Se glasses,DSC
更新于2025-09-04 15:30:14
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Analytical fitting of temperature-dependent spin-flip transitions in absorption spectra of Cr3+-doped silicate glasses
摘要： Temperature-dependent optical absorption spectra have been recorded for Cr3+ doped silicate glasses between 10 K and 773 K. Due to the intermediate ligand field strength of the Cr3+ coordination environment, overlap of the lowest-energy spin-allowed 4A2 → 4T2 band and the two spin-forbidden transitions to the 2E and 2T1 states at approximately 650 nm results in interference dips. An analytical model equation is fitted to the spectra and electronic structure parameters extracted. This represents the first time that variations of these parameters with temperature are obtained over a large temperature range, revealing characteristics of all three overlapping d-d transitions.
关键词： Chromium(III) doped glasses,absorption spectra,spectra calculations,interference dips,temperature
更新于2025-09-04 15:30:14
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Synthesis and investigation of charge transport properties in adducts of hole transporting carbazole derivatives and push-pull azobenzenes
摘要： In order to investigate the viability of a material design for bulk heterojunction (BHJ) organic solar cells, where hole transporting group is bound to the donor moiety, we report the synthesis and charge transport characteristics of 3-(diphenylamino)carbazolyl- functionalized derivatives of 2-(4-((4-(dimethylamino)phenyl)diazenyl)benzylidene)-1H-indene-1,3-dione (DMAAzi) chromophore. Three different bounding configurations were examined in these adducts. Additionally, a trityl- functionalized derivative of DMAAzi was prepared and used for comparison purposes. All of the synthesized materials form thin amorphous films from volatile organic solvents and exhibit glass transition temperatures in the range from 89 °C to 124 °C. The molecular ionization energy and electron affinity energy levels in thin films were measured. Photo-induced time of flight (ToF) method was used in to determine charge carrier drift mobilities. It was found out that the formation of deep charge trap states with local energies at approximately 0.60 - 0.78 eV takes place and has a considerable negative effect on the hole drift mobility of the investigated compounds.
关键词： charge transport,molecular glasses,carbazole,organic photovoltaics,azobenzene dyes
更新于2025-09-04 15:30:14