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Nd3+ doped new oxyfluoro tellurite glasses and glass ceramics containing NaYF4 nano crystals ??1.06?μm emission analysis
摘要： Oxyfluoro tellurite glasses with chemical composition TeO2-ZnO-YF3-NaF (TZYN), doped with Nd3+ in different concentrations were prepared by the melt-quenching technique. Judd–Ofelt analyses of Nd3+ ions in the precursor glasses were performed to evaluate the phenomenological intensity parameters Ω2,4,6. From the NIR emission spectra, characteristic parameters such as effective band with (?λeff) and stimulated emission cross section (σP) were calculated for the three observed transitions, 4F3/2 → 4I9/2, 4I11/2 and 4I13/2 and compared to other reported glasses. Based on the luminescence decay times of 4F3/2 excited state, the quantum efficiency was evaluated and it is highest for a 0.2 mol% Nd3+ doped glass (G-Nd2). Glass ceramics were obtained by controlled heat treatment of the glasses at 390oC for 5h (as determined by DSC), which is greater than the glass transition temperature Tg. Moreover, DSC results revealed that precipitation of the NdYF4 nanocrystalline phase (TC1) decreased with increasing Nd3+ concentration. X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM) investigations reveal that spherical NaYF4 nano-crystals are distributed homogeneously across the glassy matrix. The emission intensity of the 4F3/2→4I11/2 transition at 1.60 μm was enhanced in glass ceramics as compared to glasses because of the occupancy of the Nd3+ in NaYF4 nanocrystlline phase. The experimental lifetime value of 4F3/2 also enhanced from 124 to 187 μs from G-Nd2 glass to GC-Nd2 glass ceramic and decreased with increasing Nd3+ concentration.
关键词： Nd3+ doped,glass ceramics,1.06 μm emission analysis,NaYF4 nano crystals,oxyfluoro tellurite glasses
更新于2025-09-10 09:29:36
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Energy transfer studies and neutral to warm white light generation in Dy3+-Sm3+ co-doped bismuth phosphate glasses for lighting applications
摘要： A series of bismuth phosphate (BiP) glasses activated with 0.5 mol% of Dy3+ and different concentrations (0.1, 0.3, 0.5, 1.0, 1.5 and 2.0 mol%) of Sm3+ ions were prepared by melt quenching technique. These are characterized through optical absorption, photoluminescence and decay measurements for spectroscopic investigations. The luminescence spectra have been studied under selected excitation wavelengths to examine the energy transfer mechanism in the present Dy3+-Sm3+ co-doped glass by varying Sm3+ ion concentration. The lifetimes of both 4F9/2 level of Dy3+ ion and 4G5/2 level of Sm3+ ion of co-doped glasses have obtained and found to be decreased with increase in Sm3+ ion concentration. The emission intensity increased with the increase of Sm3+ ion concentration (upto 1.5 mol%) which confirms the energy transfer process between Dy3+ to Sm3+ ions. The CIE chromaticity co-ordinates (x, y), correlated color temperature (CCT) and color purity (CP) were determined from the emission data. From the CIE, CCT and CP values, it can be concluded that there is a color hue from neutral to warm white light region due to Sm3+ ion concentration and selected excitation wavelength. Hence, the obtained results strongly suggest that the present Dy3+-Sm3+ co-doped bismuth phosphate glasses could be useful for lighting applications.
关键词： Correlated colour temperature,Energy transfer,Decay profiles,Photoluminescence,Dy3+-Sm3+ co-doped glasses,Colour purity
更新于2025-09-10 09:29:36
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Investigation of modifier effect on the spectroscopic properties of Sm3+ ions in binary boro?bismuth glasses
摘要： Trivalent samarium (Sm3+)-doped boro?bismuth glass systems are prepared using the well-known melt quenching technique and studied their physical and spectroscopic properties. Theoretical optical basicity of the glasses are evaluated using the glass compositions. The optical absorption spectra are used to predict the optical band gap and bonding parameters of glasses. The ultra violet (UV) cutoff wavelength is increasing towards the higher wavelength side with increase in bismuth concentration. Judd-Ofelt parameters are obtained from absorption spectrum and are inturn used to estimate radiative properties for various excited states of the Sm3+ ions in boro?bismuth glasses. Luminescence decay curves of the 4G5/2 level in the Sm3+-doped boro?bismuth glasses are measured under 402 nm excitation. The decay times exhibit single exponential nature for lower concentrations (≤0.1 mol%) and tends towards non-exponential with increase in Sm3+ concentrations (≥0.5 mol %). The non-exponential decay curves of higher Sm3+-doped glasses are fitted to the Inokuti-Hiriyama model to know the nature of interaction for energy transfer between the Sm3+ ions. The chromaticity color coordinates for present glass systems are also evaluated and found that the luminescence color falls in the reddish-orange region.
关键词： Sm3+ ion,Judd-Ofelt theory,Spectroscopic properties,Decay curve analysis,Binary boro?bismuth glasses
更新于2025-09-10 09:29:36
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Light-emitting defects formed in GeO/SiO2 heterostructures with assistance of swift heavy ions
摘要： Germanium suboxide films and GeO/SiO2 multilayer heterostructures deposited onto Si(001) substrates using evaporation in high vacuum were modified using irradiation of 167 MeV Xe+26 ions with fluences varying from 1011 to 1013 cm?2. According to Raman spectroscopy data, the swift heavy ion irradiation does not lead to the expected decomposition of germanium suboxide in germanium nanoclusters and GeO2. Infrared absorption spectroscopy measurements show that under irradiation the GeO/SiO2 layers were intermixed with formation of Ge-O-Si bonds. We report strong photoluminescence in the visible range at room temperature, which is most probably due to Ge-related defect-induced radiative transitions. Moreover, a new infrared luminescence band (~0.8 eV) was observed in irradiated structures, which can be related to defects or defects complexes in GexSiyO2 glass.
关键词： swift heavy ions,Ge oxides,GexSiyO2 glasses,Luminescence,defects
更新于2025-09-10 09:29:36
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Performance characterisation of a real-time fiber dosimetry system using radiophotoluminescent glasses
摘要： We report the first demonstration of a real-time fiber-optic-coupled dosimetry system using Ag-activated phosphate glasses based on radiophotoluminescent (RPL) phenomena. The performance characterisation using real-time fiber RPL glass dosimetry is compared with that of real-time fiber plastic scintillation dosimetry. The inevitable build-up phenomena occurring in Ag-activated RPL glasses both during and after X-ray exposure were measured. The real-time RPL curves for the X-ray exposure region and the build-up region are analytically evaluated and fitted to the second-order polynomial functions and the sum of three exponentials, respectively. In addition, some resolved problems of real-time fiber RPL glass dosimetry are discussed.
关键词： X-ray exposure,real-time fiber dosimetry,build-up phenomena,radiophotoluminescent glasses,Ag-activated phosphate glasses
更新于2025-09-09 09:28:46
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Elastic moduli of TeO2–PbO glass system
摘要： Binary glasses (1 ? x)(TeO2) ? x(PbO) with x = 0, 0.10, 0.15, 0.20, 0.25, 0.30 mol% prepared using the melt quenching have been studied in this work. The amorphous nature of the glasses is confirmed by XRD analyses. Density, ρ and molar volume, Vm were measured for more information on structural changes. The ultrasonic velocities (longitudinal and shear) were obtained using the method of pulse-echo at 5 MHz resonating frequency. The elastic moduli, namely longitudinal (L), shear (G), Young (E) and the bulk (K) moduli were obtained from the density and ultrasonic velocities measurement. The softening temperature (TS), Debye temperature (θD), Poisson’s ratio (σ), fractal bond connectivity (d), microhardness (H) and acoustic impedance (Z) were obtained from the elastic moduli. The transition temperature ( Tg ) and thermal expansion coefficient (αP) were also calculated. The experimental elastic moduli data and the values calculated theoretically from the bond compression, Makishima–Mackenzie, and Rocherulle models were compared in this work.
关键词： Tellurite glasses,Thermal properties,Ultrasonic velocities,Elastic moduli,PbO
更新于2025-09-09 09:28:46
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The effect of Nb2O5 on fast neutron removal cross section, optical, and structural properties of some calcium borate oxide glasses containing Bi3+ ions
摘要： Background In recent years, the preparation of transparent glass in the visible region has led to the development of radiation shielding materials with measuring structure and optical properties. Also, the study on the interaction of neutron radiation with matter is important in the field of radiation protection. Purpose Preparation of transparent calcium and bismuth borate oxide glasses containing Nb5+ ions can be used as a neutron radiation shield and determine refractive index with different methods for this glass. Methods Niobium bismuth borate glasses with composition 60B2O3–20CaO–(20 ? x)Bi2O3–xNb2O5, where (x is in mol%, 0 ≤ x ≤ 10), have been prepared using conventional melt-quenching technique; the structure of each sample was studied by XRD, FTIR, and UV spectra chart analysis. Results XRD and FTIR showed that all glass samples were highly homogeneous and had structured with short-range-order/amorphous solids. The refractive index of each sample was estimated by charts of UV–Vis and FTIR, in addition to an empirical method, and we obtained values very close to each other. The refractive index values are relatively high, so this glass can be used in nonlinear studies as well as luminescence characterization. The macroscopic fast neutron removal cross sections ((cid:2)R/ρ) have calculated, for all samples, and the highest value was in sample containing 2.5% niobium pentoxide. Conclusion Bismuth borate glass containing a few niobium pentoxide can be used as a protective shield of neutrons.
关键词： Borate glass,Refractive index,UV–Vis,Oxide glasses,Optical properties
更新于2025-09-09 09:28:46
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Effect of Te Proportion on the Properties of Ge25Sb10Se65-Te Chalcogenide Glasses
摘要： The effect of Te proportion on the physical, thermal and optical properties of Ge-Sb-Se glasses was the goal of this study. In this regards, four different glasses of Ge25Sb10Se65-xTex (x=5,10,15,20) were prepared by conventional melt quenching technique in quartz ampoule. The produced samples were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR spectroscopy), Vickers hardness tester, Differential scanning calorimetry (DSC) and Thermal mechanical analysis (TMA). Based on the obtained results, we known that the overall transmittance of the samples is about 55%. For physical properties, as the Te content increases from 5% to 20%, the glass density increases from 4.52 g·cm-3 to 4.78 g·cm-3 and the Vickers hardness value is improved from 172 kg·mm-2 to 198 kg·mm-2. With respect to the thermal properties, the glass transition temperature is 551.45 K-514.56 K and the difference of Tx-Tg is more than 110 K, where Tx is the initial crystallization temperature, and Tg is the glass transition temperature. While the thermal expansion coefficient varies little, from 1.87×10-5 to 1.82×10-5. In addition, the Tg value achieved by DSC is higher than that of TMA, which gives out a reference for the measurement of characteristic temperature.
关键词： thermal properties,transmittance,characteristic temperature,Chalcogenide glasses
更新于2025-09-09 09:28:46
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Er-doped antimonite Sb2O3?PbO?ZnO/ZnS glasses studied by low-temperature photoluminescence spectroscopy
摘要： Antimonite glasses Sb2O3?PbO?ZnO/ZnS doped with ErCl3 within the range of 0.25-1.0% were prepared and investigated by means of transmission, photoluminescence excitation and photoluminescence (PL) spectroscopy. In the studied glasses, the wavelength of 522 nm was found to be the most suitable for PL excitation of Er3+ ions doped in both the NIR and VIS spectral ranges. The PL spectra excited by wavelengths at 522 and/or 514.5 nm were measured at room and low temperatures (4 K) in the wavelength range of 400–1700 nm. Low-temperature PL spectroscopy allowed us to observe both the broad luminescence of the host glass centered at around 1050 nm and the narrow emissions caused by Er3+ ions. Special attention was given to the wavelengths where the broad-band luminescence of the host overlaps with 4f–4f transitions within Er3+ ions. A broad PL band of the host glass was observed together with a superimposed narrow emission band at 985 nm (4I11/2? 4I15/2) and a narrow absorption dip at about 970 nm (4I15/2? 4I11/2). This absorption dip is a direct experimental evidence of energy transfer from the electronic structure of the host glass to 4f states of doped-in Er3+ ions. The strongest PL band at 1530 nm, representing transition from the lowest excited manifold 4I13/2 to the ground state manifold 4I15/2 was measured at 300 K and 4 K. The broadening at elevated temperature occurs primarily in the high energy part of the spectrum due to thermal excitation of electrons within the 4I13/2 manifold.
关键词： photoluminescence excitation spectroscopy,broad-band luminescence,low-temperature photoluminescence spectroscopy,erbium,antimonite glasses
更新于2025-09-09 09:28:46
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The structure of near stoichiometric Ge-Ga-Sb-S glasses: A reverse Monte Carlo study
摘要： The structure of Ge22Ga3Sb10S65 and Ge15Ga10Sb10S65 glasses was investigated by neutron diffraction (ND), X-ray diffraction (XRD), and extended X-ray absorption fine structure (EXAFS) measurements at the Ge, Ga and Sb K-edges. Experimental data sets were fitted simultaneously in the framework of the reverse Monte Carlo (RMC) simulation technique. Short range order parameters were determined from the obtained large-scale configurations. It was found that the coordination numbers of Ge, Sb and S are around the values predicted by the Mott-rule (4, 3 and 2, respectively). The Ga atoms have on average 4 nearest neighbors. The structure of these stoichiometric glasses can be described by the chemically ordered network model: Ge-S, Ga-S and Sb-S bonds are the most important. Long Sb-S distances (0.3–0.4 ? higher than the usual covalent bond lengths) are observed, suggesting that Sb atoms can be found in various local environments.
关键词： RMC,Structure,Ge-Ga-Sb-S,Diffraction,Chalcogenide glasses,EXAFS
更新于2025-09-09 09:28:46