- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Enhanced luminescent properties of Tb3+-doped transparent oxyfluoride glass-ceramics containing YF3 nanocrystals
摘要： Tb3+-doped transparent oxyfluoride glass-ceramics (GC) containing YF3 nanocrystals have been fabricated via a traditional melt-quenching route with appropriate thermal-treatment. The microstructural, luminescent and optical properties of the synthesized material were investigated systematically. The precipitated particles in the glass phase of GC540 are YF3 nanocrystals with a mean size of around 20 nm, which has been confirmed and estimated by XRD and TEM. Compared with the precursor glass (PG), the emission intensity at 545 nm (5D4→7F5) of YF3: Tb3+-doped GC is significantly enhanced (under ultraviolet and X-rays excitation) and the lifetime of GC is longer. It can be confirmed that the preferential enrichment of Tb3+ in the precipitated low-phonon-energy YF3 nanocrystals can effectively reduce non-radiative transitions. The obtained results confirm that such Tb3+-doped YF3 GC might be useful as a novel X-ray scintillating material for slow event detection.
关键词： X-ray excited luminescence spectra,luminescent properties,YF3,Glass-ceramics
更新于2025-09-23 15:22:29
-
A novel Nd <sup>3+</sup> -doped MgO-Al <sub/>2</sub> O <sub/>3</sub> -SiO <sub/>2</sub> -based transparent glass-ceramics: towards excellent fluorescence properties
摘要： Generally, glass-ceramics have superior properties compared to their parent glasses. Here, we prepared a novel Nd3+-doped MgO-Al2O3-SiO2-based transparent glass-ceramics with excellent fluorescence properties. The effects of Nd2O3 content on the structure and properties of glass-ceramics were studied, aiming to provide a key guidance for preparing this transparent glass-ceramics. The results revealed that the glass stability increased originally and then decreased with increasing Nd2O3 content, so did the variation of wavenumbers in infrared spectra. And these glass-ceramics are mainly composed of cordierite with residual glassy phase. The three phenomenological intensity parameters (Ω2,4,6) and radiative properties were estimated by Judd-Ofelt theory, and the values of Ω2 first decreased and then increased with increasing Nd2O3 content. Three main emission peaks ascribed to the transitions from 4F3/2 to 4I9/2, 4I11/2, 4I13/2 at 898, 1057, 1330 nm were observed, respectively. The branching ratios for 4F3/2→4I11/2 transition increased as the Nd2O3 content raised, and the fluorescence lifetimes of the 4F3/2 level were found to increase first and then decrease with Nd2O3 content (from 181 to 726 μs). The excellent fluorescence properties indicate that this novel glass-ceramics can be used as a potential solid-state optical functional material for 1.06 μm laser emission.
关键词： MgO-Al2O3-SiO2,Judd-Ofelt theory,Nd3+-doped,Transparent glass-ceramics,Solid-state optical functional materials
更新于2025-09-23 15:22:29
-
Structural transformations and spectroscopic properties of Ni-doped magnesium aluminosilicate glass-ceramics nucleated by a mixture of TiO2 and ZrO2 for broadband near-IR light emission
摘要： Ni:MgAl2O4 spinel shows a reversible random Ni2t site redistribution with increasing temperature. With the aim of determining the influence of the structure evolution induced by heat-treatment on the nature of luminescence centers in NiO-doped spinel-based magnesium aluminosilicate glass-ceramics nucleated by a mixture of TiO2 and ZrO2, the detailed spectroscopic study of the initial glass during its heat-treatments at increasing and decreasing temperatures has been performed and accompanied by an XRD analysis and Raman spectroscopy. The initial glass was X-ray amorphous. Its optical spectrum is mainly formed by absorption of [5]Ni2t sites with a small amount of [4]Ni2t ones. Crystals of the nucleating catalyst, ZrTiO4, about 4 nm in size, appear during heat-treatment at 800 °C, while the absorption spectrum of Ni2t ions remains near unchanged. At 850 °C, spinel crystals with size of about 6 nm precipitate, which is accompanied by a broadband luminescence in the near-IR centered at 1330 nm with a bandwidth of 380 nm. At 950 °C, there is a slight reduction in intensity of absorption bands attributed to [6]Ni2t site redistribution with increasing temperature. A decrease in the amount of the [6]Ni2t luminescent centers is not accompanied by a decrease in the luminescence intensity because of the increased size of spinel crystals. Additional low-temperature heat-treatment does not lead to a redistribution between [6]Ni2t sites in spinel crystals in favor of [6]Ni2t ones. An increase of the luminescence intensity after low-temperature heat-treatment is associated with additional spinel crystallization.
关键词： Glass-ceramics,Luminescence,Spinel,Heat-treatment,Nickel,Absorption
更新于2025-09-23 15:21:21
-
Atomic picture of crack propagation in Li <sub/>2</sub> Oa??2SiO <sub/>2</sub> glassa??ceramics revealed by molecular dynamics simulations
摘要： Fundamental understanding of the interaction between glass and ceramic phases with a running crack and the mechanisms by which propagation is hindered or altered as compared to the precursor parent glasses remains elusive for the lithium disilicate glass-ceramics. We herein conduct extensive molecular dynamics simulations to reveal some atomic details that are otherwise extremely challenging to be probed by experiments. The results show that the crack propagation pathway in glass-ceramics is dramatically different as compared to the precursor parent glass. In glassy sample, clean crack branching seems to be triggered by multiple cavitation events ahead of crack tip. In glass-ceramic samples, however, branching is characterized by microcracks at multiple glass-nanocrystal interface sites, clean nanocrystal cleavage along certain crystalline plane, and even secondary cracks due to the percolation of multiple microcracks. Additionally, the nanocrystal distribution, total volume fraction, and aspect ratio also have pronounced effects on the propagation of a primary crack and can lead to very diverse crack patterns.
关键词： lithium disilicate glass-ceramics,crack branching,microcracks,crack propagation
更新于2025-09-23 15:21:01
-
Copper nanoparticles enhanced luminescence of Eu3+ doped lead tellurite glass ceramics
摘要： Structural, optical and magnetic properties of some lead tellurite glass ceramics doped with europium(III) ions and co-doped with fixed amounts of metallic copper nanoparticles (CuNPs) or copper(II) ions (via CuO) were investigated. Samples in the (Eu2O3)x·(TeO2)80·(PbO)(19.7-x)·(CuNPs)0.3 and (Eu2O3)x·(TeO2)80·(PbO)(19.7-x)·(CuO)0.3 systems with 0 ≤ x ≤ 10 mol% were obtained and investigated for the first time. Several techniques such as X-ray diffraction, UV-VIS, EPR and luminescence spectroscopies and density and magnetic susceptibility measurements were used in order to characterize the samples. XRD data show that the samples with low Eu2O3 contents (x ≤ 1 mol%) are amorphous while for higher europium oxide contents (x > 1 mol%) are glass ceramics. They also reveal that increasing the Eu2O3 content of samples the symmetry around the europium ions changes from face centered cubic to monoclinic. These symmetry changes are confirmed by the photoluminescence data. In addition, photoluminescence data show that the co-doping with metallic copper nanoparticles enhances the emission peaks of europium ions. UV-VIS absorption spectra show the presence of six coordinated copper (II) ions located at sites with a distorted octahedral symmetry. The EPR data confirm the presence of copper (II) ions in all the studied samples. Magnetic susceptibility measurements suggest the presence of europium ions in both their 3+ and 2+ valence states and evidence an important clustering tendency of europium ions even for low Eu2O3 contents.
关键词： EPR,UV-VIS,Photoluminescence,Magnetic susceptibility,Lead-tellurite glass ceramics,XRD
更新于2025-09-23 15:21:01
-
[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Fabrication and Characterization of New Phosphate Glasses and Glass-Ceramics Suitable for Drawing Optical and Biophotonic Libers
摘要： Rare earth doped phosphate glasses are attractive materials for the engineering of photonic devices, due to their easy processing, good thermal stability, excellent optical properties and high rare-earth ions solubility [1]. Besides, phosphate glasses with a P2O5 content of 50 mol% have been shown to be suitable for fiber drawing. It is well known that if the rare-earth ions are located in crystalline phase of desired nature and structure, the spectroscopic properties of the glasses can be enhanced [2]. Therefore, efforts have been focused on the development of new glass-ceramics (GCS) obtained from the heat treatment of glasses, as these engineered materials possess some of the glass properties (large flexibility of composition and geometry) but also some advantages of the RE-doped single crystals (high absorption and emission as well as long lifetimes). In this presentation, we will first discuss how new active phosphate glasses can be prepared with a bioactivity functionality and their composition tailored to enhance their spectroscopic properties. We will show that the heat treatment does not necessarily lead to the bulk precipitation of rare-earth doped crystals (see figure 1). Therefore, we will present a new route to prepare rare-earth doped crystals containing glasses using the direct doping method (schematic presented in Figure 2). We will review the main challenge with this novel route of preparing glasses, related to the survival and dispersion of the particles in the glasses. Finally, we will demonstrate that some of the promising glasses can be drawn into optical fibers with broad luminescence over 70 nm of bandwidth and also into biophotonic fiber in the prospect of developing an innovative biosensor.
关键词： glass-ceramics,biophotonic fibers,phosphate glasses,rare-earth ions,optical fibers
更新于2025-09-23 15:19:57
-
Effects of raw material ratio and post-treatment on properties of soda lime glass-ceramics fabricated by selective laser sintering
摘要： A reliable method for fabricating soda lime glass-ceramics by selective laser sintering was demonstrated. The effect of the ratio of glass powder to epoxy resin and sintering process on the properties and microstructure of glass-ceramics was investigated. Research shows that: with the improvement of glass powder proportion, sintering shrinkage rate declined and mechanical strength could be improved gradually. When the mass ratio of glass powder and epoxy resin powder was 18:1 and heat-holding at 740℃ for 3 h, the shrinkage rate of the sample was 21.11% and the bending strength reached 95.45 MPa. Therefore, this research laid a foundation for 3D printing to fabricate high performance and complex structure glass-ceramics.
关键词： Selective Laser Sintering,3D printing,Glass-ceramics,Sintering
更新于2025-09-23 15:19:57
-
Crystallization and spectroscopic characterizations of binary SrO-B2O3 glasses doped with LiF, NaF, CaF2, or TiO2
摘要： Glasses based on the basic chemical composition of binary strontium borate (SrO 50-B2O350 mol%) together with samples containing dopant (2%) with one of the fluorides (LiF, NaF, CaF2) or TiO2 have been synthesized through the routinely melting and annealing technique. Collective structural, optical, and thermal properties have been measured for the prepared glasses. X-ray diffraction and SEM measurements were carried out for their corresponding glass-ceramics which were synthesized by controlled thermal heat treatment with two-step regime. FT infrared absorption spectra reveal composite vibrational modes in the mid-range 400–1600 cm?1 which are related to the co-presence of both triangular and tetrahedral borate building units in their particular different wavenumber sites. The low dopant level did not make any distinct variations in the IR spectra. X-ray diffraction patterns elucidate the formed crystal phases after crystallization mainly strontium metaborate and other related borate phase and the LiF shows no distinct variation while NaF2 and CaF2 induce the formation of additional crystalline Na-containing or Ca-containing phases besides the formation of NaF or fluorite (CaF2). TiO2 acts as a nucleating agent and also separate as rutile. The crystallization behavior has been correlated with the assumption of the tendency of SrO to induce phase separation in the host binary borate glass and controlled heat treatment initiates the separation of strontium metaborate crystalline phase in the base binary SrO-B2O3 in accordance with its composition and the role of dopants is found to be varying with the type of dopant. The measured thermal expansion parameters of the prepared glasses reveal variations in their values for transformation and softening temperatures depending on the type of added dopant. The changes in the thermal expansion coefficients in the different parts of the thermal curves are related to the ability of the network to absorb lattice expansion through bending of the bonds. The uniform observed ultraviolet absorption bands are related to traces of iron (Fe3+) ions present as impurities.
关键词： LiF,CaF2,NaF,Thermal expansion,FTIR optical spectra,SrO.B2O3 glass,Glass-ceramics,TiO2
更新于2025-09-19 17:15:36
-
Controlled nanoa??crystallization of IR frequencya??doubling Cd <sub/>4</sub> GeS <sub/>6</sub> crystal in chalcogenide glass
摘要： Crystallization of IR frequency-doubling nanocrystals in chalcogenide glasses is a promising approach to achieve novel nonlinear optical materials. However, controllable glass crystallization remains challenging. In this study, IR-transparent chalcogenide glass-ceramics containing novel Cd4GeS6 IR frequency-doubling na- nocrystals (about 60-80?nm) are fabricated through controlled nano-crystallization. Nanocrystalline structure of the Cd4GeS6 nano-crystallized glass-ceramics is inves- tigated in detail through X-ray diffractometer, field emission scanning electron mi- croscope, and Raman scattering techniques. The structural similarity of [Cd4GeS6] polyhedron in the network structure of as-prepared glass is found to be responsible for the nucleation of Cd4GeS6 crystal. A unique microstructure of Cd4GeS6 nanocrys- tals embedded GeS2 phase-separated structure is discovered in samples thermally treated at high temperatures (370°C and 380°C). This study would not only shed more light on glass crystallization mechanism but also provide a feasible approach for the design and fabrication of new IR frequency-doubling materials through glass crystallization.
关键词： Cd4GeS6,microstructure,glass-ceramics,chalcogenide glasses,crystallization
更新于2025-09-19 17:13:59
-
Perovskite quantum dots growth in situ in transparent medium for short wavelength shielding
摘要： High energy ultraviolet (UV) and blue light (short wavelength) radiation is proved to be harmful to human eyes, skin, and biological genomes. However, developing effective shielding materials providing protect from short wavelength is still a great challenge. Here, Eu3+-doped CsPbBr3 embedded in a transparent glass medium is proved to shield the short wavelength from 200 to 475 nm with high performance, which is prepared by a facile and efficient melting-quenching technique. The uniform distribution of the CsPbBr3 quantum dots (QDs) growth in situ from the transparent glass matrix ensures the high transmittance (> 90%) at the long wavelength (520-800 nm). In addition, the excellent short wavelength shielding ability of the Eu3+-doped CsPbBr3 glass ceramics (EGC) is demonstrated even suffered with accelerated weathering tests as long as 480 h. Moreover, the cell viability of A549 cells is well preserved thanks to the completely blocked blue light by the as-obtained EGC, which unambiguously demonstrates the promising application of EGC as short wavelength shielding materials.
关键词： perovskites,glass-ceramics,short wavelength shielding,quantum dots
更新于2025-09-19 17:13:59