氟氧硅酸盐玻璃钐离子的光谱参数计算和荧光光谱分析

本工作针对Sm3+掺杂氟氧硅酸盐(NBZASB)玻璃进行了制备合成,对玻璃的吸收和荧光光谱展开了测试与分析.根据吸收光谱进行了光谱参数的计算,获得了氟氧硅酸盐玻璃中Sm3+离子的晶场调节参数,进而计算得到各能级光谱参数,其中钐离子4G5/2能级到6H9/2和6H7/2到两个能级跃迁的自辐射跃迁几率分别为187 s-1和107s-1,荧光分支比分别达到47％和27％.在商用365 nm和254 nm紫外光激发下Sm3+掺杂NBZASB玻璃呈现明亮的橙红色光,发射光谱表明其最强发射峰位于600 nm.激发光谱表明,氟氧硅酸盐玻璃中Sm3+离子的有效受激波长范围覆盖了从345 nm紫外光到472 nm绿色光等六个激发峰的宽光谱区域,多种商用激光器、激光二极管及发光二级管都可以有效激发Sm3+掺杂NBZASB玻璃.     

Ce3+‐ and Dy3+‐Doped Oxyfluoride Borosilicate Glasses with Near White Luminescence

A series of Ce³⁺/Dy³⁺‐doped oxyfluoride borosilicate glasses prepared by melt‐quenching method are investigated for light‐emitting diodes applications. These glasses are studied via X‐ray diffraction (XRD), optical absorption, photoluminescence (PL), color coordinate, and Fourier transform infrared (FT‐IR) spectra. We find that the absorption and emission bands of Ce³⁺ ions move to the longer wavelengths with increasing Ce³⁺ concentrations and decreasing B₂O₃ and Al₂O₃ contents in the glass compositions. We also discover the emission behavior of Ce³⁺ ions is dependent on the excitation wavelengths. The glass structure variations with changing glass compositions are examined using the FT‐IR spectra. The influence of glass network structure on the luminescence of Ce³⁺/Dy³⁺ codoped glasses is studied. Furthermore, the near‐ideal white light emission (color coordinate x = 0.32, y = 0.32) from the Ce³⁺/Dy³⁺ codoped glasses excited at 350 nm UV light is realized.     

Luminescence of Eu‐Doped Transparent LuPO4 Glass‐Ceramics

Dual valence Eu‐doped transparent glass‐ceramics containing LuPO₄ nanocrystals were fabricated by melt‐quenching technique in air atmosphere. Their luminescent properties were systematically investigated by excitation, emission spectra, and decay lifetime measurements. The prominent Stark splitting, low forced electric‐dipole ⁵D₀ – ⁷F₂ transition and long decay lifetimes of Eu^{3 +} emission for glass‐ceramics reveal the incorporation of Eu^{3 +} into LuPO₄ nanocrystals. The enhanced Eu^{2 +} emission and reduction mechanism of Eu^{3 +} to Eu^{2 +} after crystallization are discussed briefly. Our results indicate that transparent LuPO₄ glass‐ceramics may find applications in photonics.     

Nd3+‐Doped Silicate Glasses as an Efficient Color Filter to Improve the Color Gamut of a White LED

Nd³⁺‐doped silicate glass (Nd‐glass) was employed as a color filter for a white LED based on red and green phosphor (RG‐LED), to manipulate the photoluminescence spectral shape and thus to provide a wider color gamut. The hypersensitive transition of Nd³⁺:⁴I_9/2→⁴G_5/2,²G_7/2 was adjusted via glass composition and Nd concentration, and improved absorbance as well as reduced the absorption bandwidth. The effective absorption of the Nd‐glass at ~580 nm reduced the spectral linewidth of the green and red emissions, improving the color reproduction range. The color gamut of the RG‐LED was improved from 75.3% to 81.6% NTSC by the introduction of Nd‐glass as a color filter. Reliability under high operating current and high temperature were also examined and discussed.     

CdS and CdSe Quantum Dot-Embedded Silicate Glasses for LED Color Converter

Silicate glasses with CdS and CdSe quantum dots (QDs) were synthesized for application as an inorganic color converter for a 450-nm blue light-emitting diode (LED). CdO and ZnS (or ZnSe) were added, and heat treatment conditions were changed to control QD formation within the silicate matrix. Absorption spectra and high-resolution transmission electron microscopy confirmed the QD formation. Variations in absorption and photoluminescence (PL) spectra were observed with CdSe QD-embedded glasses when heat treatment conditions varied, whereas glasses with CdS QDs did not show noticeable variation. QD-embedded glasses were then mounted on top of a 450-nm LED chip to make a color-converted LED, and their electroluminescence and PL spectra as well as CIE color coordinates were investigated. The practical potential of QD-embedded glasses as an inorganic color converter has been observed, and their spectral properties were discussed.     

Eu3+ Doped Lithium Silicaborate Glasses for LED Application

Glass Physics and Chemistry - In the present study Eu2O3 doped Li2O–Si2O–B2O3 glasses (LSBE) were synthesized by the melt quench technique. The physical, thermal, and spectroscopic...     

Electric Field‐Induced Light Scattering in Eu‐Doped PMN‐PT Transparent Ceramics

Highly transparent Eu‐doped Pb(Mg_1/3Nb_2/3)O₃–PbTiO₃(PMN‐PT) ferroelectric ceramics were obtained by a two‐stage sintering method. Eu doping play a significant role in the domain structures of PMN‐PT ceramics and resulted in different light scattering responses under electric field. The dielectric behaviors, ferroelectric properties, and domain configurations in the ceramics with increasing Eu doping concentration were studied, which were consistent with the electric field‐induced light scattering responses.     

Conductivity Studies of Silver‐, Potassium‐, and Magnesium‐Doped Hydroxyapatite

We report the electrical transport properties of silver‐, potassium‐, and magnesium‐doped hydroxyapatites (HAs). While Ag+ or K⁺ doping to HA enhances the conductivity, Mg⁺² doping lowers the conductivity when compared with undoped HA. The mechanism behind the observed differences in ionic conductivity has been discussed using the analysis of high‐temperature frequency‐dependent conductivity data, Cole–Cole plots of impedance data as well as on the basis of the frequency dependence of the imaginary part (M″) of the complex electric modulus. The f_max of modulus M″ decreased in silver‐ and potassium‐doped samples in comparison with the undoped HA.     

Low‐Energy Ion‐Scattering Spectroscopy of Modified Silicate Glasses

Low‐Energy Ion‐Scattering (LEIS) spectroscopy is a technique with a unique sensitivity to the elemental composition of the top atomic layer of a solid surface. LEIS measurements of ternary silicate glasses modified with Na₂O, Cs₂O, CaO, and BaO show that the compositions of the as‐cast (melt) surface and the in‐vacuum fracture surface often differ. While the as‐cast surface is usually depleted of alkali ions (Na⁺ or Cs⁺) compared to the nominal (batch) glass composition, there is often strong accumulation of the same mobile cations on the fresh fracture surface. Depth profiles obtained by sputter etching reveal elemental concentration gradients normal to the glass surface. The final concentrations often fail to reach the nominal glass composition, suggesting the likely presence of preferential sputtering effects and thereby the distortion of the measured concentration gradient. At present, the lack of reliable standards and preferential sputtering effects in the LEIS of multicomponent glasses limit somewhat the absolute chemical composition and structural information that can be obtained with this otherwise unique and powerful method of surface analysis.     

Surface Analysis of Cr2O3‐, CoO‐, and Al2O3‐Doped Iron–Phosphate Glasses at High Temperature

Surface structures of iron–phosphate glasses were examined using X‐ray photoelectron spectroscopy (XPS). Cr₂O₃, CoO, and Al₂O₃ were introduced to the glass by the replacement of a part of Fe₂O₃, and the simulated fission products are also added. The obtained glasses showed high chemical durabilities by MCC‐1 test. In situ high‐temperature and room‐temperature XPS measurements were conducted on the polished sample surfaces and also those after 1‐week chemical durability test. Unique trends were observed in XPS spectra on heating and after the chemical durability test, respectively. Nature of the glass surface of iron–phosphate glasses was explained from the point of view of surface energy, and the origin of high chemical durability and the effect of chromium ions were discussed based on the changes on surface composition and valence states of transition‐metal ions.     

Physical and Mechanical Properties of Barium Alkali Silicate Glasses for SOFC Sealing Applications

The physical and mechanical properties of two barium alkali silicate glasses were determined as a function of temperature. Their Young's modulus and Poisson's ratio were determined by resonant ultrasound spectroscopy; their viscosity, thermal expansion, and glass transition temperature were determined using a thermomechanical analyzer. The wetting behavior of the two glasses on alumina and 8 mol% yttria stabilized zirconia (8YSZ) substrates was determined by measuring contact angles in air as a function of temperature and time. Values of Young's modulus for both glasses were in good agreement with those predicted by the Makishima and MacKenzie model. The physical and mechanical properties of these glasses are discussed in the context of their potential use for sealing applications in solid-oxide fuel cells.     

Samarium‐Doped Oxyfluoride Glass‐Ceramic as a New Fast Erasable Dosimetric Detector Material for Microbeam Radiation Cancer Therapy Applications at the Canadian Synchrotron

There is a special need to develop a dosimetry technique with a large‐dynamic range and high‐spatial resolution to characterize the microstructured X‐ray beams used in microbeam radiation therapy (MRT) for cancer. We report the synthesis and characterization of oxyfluoride glass‐ceramic (SiO₂–Al₂O₃–CaF₂–CaO–SmF₃) plates, which contain trivalent‐samarium‐doped calcium fluoride (CaF₂:Sm³⁺) nanocrystals, for use as a dosimetric detector material, particularly for MRT applications. Our approach utilizes the extent of Sm³⁺→Sm²⁺ valence reduction caused by X‐ray irradiation as a probe of the X‐ray dose delivered; and confocal fluorescent microscopy is used to read out the distribution of valence reduction through the photoluminescence (PL) signal. Our study showed that the Sm³⁺→Sm²⁺ valence reduction takes place in CaF₂ nanocrystals, but not in the glass matrix. The Sm²⁺ shows PL emission predominantly due to the fast 4f⁵5d¹→⁷F₀ transition, which allows us to read out the detector plate at a high scanning speed. Further, our experiments showed that the detection dose range reaches several thousands of grays, and X‐ray dose distribution is detected at a micrometer scale. In addition, the Sm²⁺ signal can be erased either by heating the irradiated sample at a suitable high temperature or by exposing it to UV light; and the erased glass‐ceramic plate is reusable. The new Sm‐doped oxyfluoride glass‐ceramic with CaF₂ nanocrystals reported in this work shows potential for practical use in high‐dose and high‐resolution dosimetry for MRT.     

Structural Characteristics and Electrokinetic Potential of Silicate Porous Glasses Doped with Silver Iodide

Glass Physics and Chemistry - The structural (volume porosity, specific surface area, and average pore radius) and electrokinetic characteristics are studied for silicate and AgI-doped microporous...     

Network Rearrangement in AgI‐Doped GeTe4 Glasses

The structure of (GeTe₄)_1?x(AgI)_x (x = 0.15 and 0.25) glasses has been investigated by X‐ray and neutron diffraction as well as extended X‐ray absorption spectroscopy (EXAFS) and Raman spectroscopy. Large‐scale structural models have been obtained by fitting simultaneously the experimental datasets in the framework of the reverse Monte Carlo simulation technique (RMC). Short‐range order parameters have been calculated and compared with that of GeTe₄. Doping with AgI affects the structure of the host GeTe₄ matrix in two ways. First, while Te is essentially twofold coordinated in GeTe_4, its coordination number is as high as ~2.9 ± 0.3 for x = 0.25. The change is mainly due to the increased fraction of Te–Te bonds. Second, Ge atoms remain fourfold coordinated but the tetrahedral symmetry is distorted due to the elongation of some Ge–Te bonds. The incorporation of AgI in the GeTe₄‐based host covalent matrix and the Te coordination increase explains the enhanced thermal stability of (GeTe₄)_1?x(AgI)_x in the supercooled liquid‐state hindering the crystallization of Te found in case of GeTe₄ glass.     

Er3+ Ions‐Doped Germano‐Gallate Oxyfluoride Glass‐Ceramics Containing BaF2 Nanocrystals

Er³⁺ ions‐doped germano‐gallate oxyfluoride glass‐ceramic containing BaF₂ nanocrystals was prepared through conventional melt quenching and subsequent thermal treatment method. X‐ray diffraction patterns and transmission electron microscope images confirmed the formation of BaF₂ nanocrystals in glass‐ceramics. Preferential incorporation of Er³⁺ ions into the BaF₂ nanocrystals were confirmed by the absorption spectra and emission spectra, and enhanced upconversion emission and infrared emission were observed. Relatively high transmittance in the mid‐infrared region indicated great potential of this germano‐gallate oxyfluoride glass‐ceramics as host materials for the efficient mid‐infrared emission from rare‐earth ions.     

Enhanced Thermostability,Thermo‐Optics,and Thermomechanical Properties of Barium Gallo‐Germanium Oxyfluoride Glasses and Glass‐Ceramics

Serial substitutions of BaF₂ for BaO in BaO–Ga₂O₃–GeO₂ glasses were performed, and the effects of the substitutions on the glass properties were investigated. The glass transition temperature, density, refractive index, thermo‐optics coefficient, and figure of merit for thermal shock decreased with the replacement of oxygen by fluorine. On the other hand, the glass‐forming ability increased. Fluorine substitution removed the absorption band of hydroxyl near 2.9 μm. Raman scattering spectroscopy was used to characterize the fluorogermanate glasses. The crystallization process of the glass‐ceramics under different heat‐treatment conditions was also investigated using differential scanning calorimetry, X‐ray diffraction, scanning electron microscopy, and atomic force microscopy. The thermal and mechanical properties were improved by controlling the crystal size of the near‐ and middle‐infrared transparent glass‐ceramics.     

A Unique Approach to Characterization of Sol‐Gel‐Derived Rare‐Earth‐Doped Oxyfluoride Glass‐Ceramics

Using the sol‐gel route Nd³⁺‐doped oxyfluoride glass‐ceramics were prepared. LiYF₄ and YF₃ crystals were deposited in the glass‐ceramics and their size, distribution, and amount ratio were varied by changing the compositions and heating temperatures. The incorporation of Nd³⁺ ions into both the fluoride crystals was confirmed by the high‐resolution elemental mapping of the glass‐ceramics. The incorporated Nd³⁺ ions showed up and down conversion photoluminescence whose properties were obviously different among the samples. The preliminary site analysis for Nd³⁺ ions was carried out using a unique approach associated with the Prony series approximation. Finally, the approach was found to be useful for the analysis of materials that are structurally complicating.     

UV-Visible and IR Spectroscopic Studies of Gamma Irradiated Transition Metal Doped Lead Silicate Glasses

Lead silicate (LS) glasses of the basic composition PbO 75%, SiO₂ 25% together with samples containing (∼0.1%) of transition 3d metal oxides (Ti→Cu) were prepared. UV/VIS optical analysis for as prepared and after successive gamma irradiated samples were used to shed more light on the structural modifications that occur due to different dopants and different irradiation doses. The UV-Vis. spectral analysis for undoped glass shows induced absorption bands at 205–400 nm which are assumed to be correlated with the base host glass and dopant transition metal ion doped glasses and dose of irradiation. The positions of the bands are observed to change slightly by gamma irradiation due to the combined effect of induced defects from the host base glass or the transition metal added. Gamma irradiation is observed to cause a decrease in the intensities of the IR absorption bands of the prepared samples accompanied by losing sharpness. These features are related to more amorphicity or disorder by irradiation or to the possible changes in bond angle or bond length in the building groups arrangement.     

Mechanism for the Radiolytically Induced Decomposition of Soda–Silicate Glasses

A mechanism is proposed for the radiolysis which occurs in soda-silicate glasses when they are irradiated. The mechanism is consistent with the observations of the reaction products which are produced and the rates at which the decomposition proceeds.     

Ga–Sb–S Chalcogenide Glasses for Mid‐Infrared Applications

In this study, a novel chalcogenide glass system, Ga–Sb–S, is reported. The glass‐forming ability, the physical properties, and the structure are investigated; and the potential applications of the glasses are evaluated. The compositions consisting of ~3%–10% Ga, ~29%–37% Sb, and ~57%–63% S can form glasses. The glasses have a wide transparent window of ~0.8–14 μm, high linear refractive indices of ~2.62–2.70 (@10 μm), high third‐order nonlinear refractive indices of ~12.4 × 10^?14 cm²/W (@ 1.55 μm), low phonon energy, and large rare earth solubility. These favorable properties make them promising materials for mid‐infrared applications such as thermal imaging, nonlinear optics, and lasers.