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Effect of pre-existing nuclei on crystallization during laser welding of Zr-based metallic glass
摘要： In this study, experiments are carried out in laser welding of a Zr-based (Zr52.5Ti5Al10Ni14Cu17.9) bulk metallic glass (BMG), pre-existing nuclei nucleus density has significant influence on its crystallization behavior. Based on the classical nucleation/growth theory, it is concluded that a small amount of pre-existing nuclei in a BMG can shift the time-temperature-transformation (TTT) curve from a well-known ‘C-shape’ to a ‘ε-shape.’ This result provides fundamental understanding on why the shape of the TTT curve for a heating process is different from that for a cooling process for the same BMG. Two quality factors were defined as a measure of the effect of pre-existing nucleus density. By integrating the classical nucleation/growth theory with the heat transfer model, the evolution of crystalline phase during laser welding for a BMG with pre-existing nuclei was studied, and the modeling predictions compared favorably with the experimental results.
关键词： Crystallization,Nucleation and growth,Laser processing,Metallic glasses,Amorphous alloys
更新于2025-11-28 14:24:20
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Synthesis and characterization of Er3+/Cu+-codoped fluorophosphate glasses
摘要： NaPO3-ZnF2 binary fluorophosphate glasses doped with trivalent erbium and monovalent copper were synthesized by the conventional melting and casting method using ErF3 and CuCl as starting materials. The samples were systematically investigated using X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analysis. X-ray powder diffraction patterns confirmed that the as-prepared compounds were all amorphous. The glass transition temperature (Tg) was observed around 230°C by DSC analysis, while the thermal stability range (?T) was estimated to be between 90 and 140 °C. The measured value of the refractive index (n) was measured as 1.502 at a wavelength of 632.8 nm. Thermal annealing of the samples was performed at different temperatures above Tg for various heat-treatment times. During these steps, monovalent copper and sodium ions were expected to be reduced, forming metallic nanoparticles. This transformation lead to coloration changes, depending on the annealing time and temperature, with respect to the transparency of the glasses. These spectroscopic changes are related to the plasmonic effects induced by the presence of both Cu and Na metallic nanoparticles, which promote red shift due to absorption. The VIS-NIR absorption spectra of the prepared glasses were investigated in the frame work of standard Judd-Ofelt (J-O) theory, which was used to determine the J-O intensity parameters, radiative transition probabilities and branching ratios for Er3+ ions embedded in the glasses. The calculated intensity parameters (Ω2,4,6) were compared to those obtained for Er3+ in several other glasses.
关键词： Nanoparticles,Fluorophosphate glasses,Absorption,Judd-Ofelt theory,Optics
更新于2025-10-22 19:40:53
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Remarkable laser-driven upconverting photothermal effect of Cs3LnF6@glass nanocomposites for anti-counterfeiting
摘要： Currently, advanced security strategies have aroused widely interest in anti-counterfeiting field to ensure the authentic items difficult to be replicated. Herein, cubic Cs3LnF6 (Ln = Y, Yb, Lu, Sc) nanocrystals embedded glasses are successfully prepared via an in-situ glass crystallization strategy. Emitting centers, such as Eu3+, Er3+, Ho3+ and Tm3+, can be incorporated into the precipitated Cs3YF6, Cs3YbF6 and Cs3LuF6 crystal lattices but remain in glass matrix rather than in Cs3ScF6 crystals for large ionic radius mismatch between lanthanide activators and Sc3+ host ions. It is demonstrated that upconverting quantum yields of all the Yb/Er: Cs3LnF6@glass samples are higher than those of well-known cubic/hexagonal Yb/Er: α/β-NaYF4@glass samples. Specifically, Yb/Er: Cs3LuF6@glass exhibits a maximal quantum yield of ~0.30%, which is superior to Yb/Er: β-NaYF4 @glass (~0.19%). Impressively, Er: Cs3YbF6@glass shows a remarkable 980 nm laser-induced photothermal effect, leading to significant alteration of upconversion emissive color from red to green with increase of incident laser power. As a prototype of the concept for practical application, a series of luminescent patterns using Er: Cs3YbF6@glass upconverting inks are constructed by a screen-printing technique and show distinct laser-power-sensitive emissive colors, being feasible for high-level anti-counterfeiting. The present work exploits a new anti-counterfeiting strategy by developing highly efficient laser-induced upconverting photothermal materials.
关键词： Anticounterfeit,Nanocomposites,Upconversion,Lanthanide ions,Photothermal effect,Luminescent glasses
更新于2025-10-22 19:38:57
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Comparative investigations of gadolinium based borate glasses doped with Dy3+ for white light generations
摘要： Gadolinium-based borate glasses doped with Dy3+ ions were developed by melt quenching technique for white light generation. The title glasses were examined by XRD, optical absorption spectra and Photoluminescence spectra. From photoluminescence emission spectra, the higher intensity peak was observed at 575 nm (4F9/2 → 6H13/2) for present glass samples. The experimental decay rate (τexp) of 4F9/2 transition of Dy3+ ions were found to be a decline in increasing of Dy2O3 content. The Inokuti-Hirayama (IH) model is used to explain the non-exponential decay time by putting S=6, which confirmed that the energy is transfer through cross-relaxation is of dipole–dipole nature among the Dy2O3. The values of color coordinates match with the range of white light of chromaticity (CIE) diagram. The color chromaticity coordinates (u, v) and color correlated temperature (CCT) values for present glasses were correlated with standards, which are closely related to the standard, therefore, the prepared glasses might be helpful for different photonic applications such as white LEDs.
关键词： luminescence,glasses,borate,spectra,Gadolinium
更新于2025-09-23 15:23:52
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HMD-based cover test system for the diagnosis of ocular misalignment
摘要： The diagnosis of ocular misalignment is difficult and needs examination by ophthalmologists and orthoptists. However, there are not enough qualified personnel to perform such diagnoses. The eye position check is in part systematized. With this check system, we can detect not only the symptoms but also the angle and the extent of strabismus. However, the types of strabismus that can be detected with this technique are limited to exotropia. The purpose of this study is to develop a simplified check system to screen at least the presence of strabismus apart from the type of strabismus or amount of ocular deviation. First, we digitalized the check process. Specifically, we digitized the elemental technology, i.e., the cover–uncover function, required for automation of the typical cover test for eye position check. Furthermore, we developed and implemented an abnormality determination process and evaluated the performance of the system through this experiment, the results of which indicated a higher detection capability than the conventional cover test performed by ophthalmologists and orthoptists.
关键词： 3D glasses,Abnormality of eye position,Digitalization of check process,Cover-uncover test
更新于2025-09-23 15:23:52
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Optical, structural and luminescence properties of oxyfluoride phosphate glasses and glass-ceramics doped with Yb3+
摘要： The impact of Al2O3 and Y2O3 addition on the structure, Yb3+ luminescence and crystallization is investigated for glasses in the P2O5-SrO-Na2O system. Although the addition of Al2O3 and Y2O3 leads to a more connected phosphate network as evidenced using IR and Raman spectroscopies and increases the glass transition temperature, it does not affect strongly the site of the Yb3+. The addition of Al2O3 and Y2O slightly decreases the rate of the glass crystallization. Surface crystallization occurs upon heat treatment. Crystallization was confirmed by the presence of sharp peaks in the XRD patterns of the glasses. Independently of the glass composition, multiple different crystalline phases precipitate in the glasses upon heat treatment. The precipitation of the Na1O7P2Yb1 crystal phase leads to an increase of the excited state 2F5/2 lifetime of Yb3+ and also of the bandwidth of the Yb3+ emission band centered at 1μm.
关键词： nucleation and growth,Yb3+ doped phosphate glasses,Raman & Infrared spectroscopies,Yb3+ luminescence properties,heat treatment
更新于2025-09-23 15:22:29
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Transverse phonons and intermediate-range order in Sr-Mg fluorophosphate glasses
摘要： Vibrational and ultrasonic spectroscopies have been employed to study the composition and polarization dependence of the vibrational and elastic properties of the pseudo-binary mixed fluoride-phosphate glass-forming system xSr(PO3)2-(1-x)(0.62MgF2-0.38AlF3) with x: 0, 0.04, 0.06, 0.1, 0.15, 0.2, 0.3, 0.4, 0.8, 0.9 and 1. Composition-induced alterations in the short-range order have been quantitatively followed by means of Raman and IR spectroscopies. The analysis has shown that the incorporation of the phosphate groups in the fluoride network results in a less interconnected network with suppressed rigidity. The specific amorphous materials have been used as a model system in terms of wide glass-forming ability to elucidate the effect of variation in connectivity between the fluoride and phosphate sub-networks on the Boson peak nature. Emphasis has been given in the low-frequency Raman phenomenology, which in conjunction with the elastic properties allowed us to establish a possible link between the Boson peak and the transverse phonons in these glasses.
关键词： phonons,amorphous materials,oxide glasses,Boson peak,elastic properties,Raman spectroscopy,ATR spectroscopy
更新于2025-09-23 15:22:29
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Structure and Crystallization of Glasses in the MnNbOF5–BaF2–InF3 System
摘要： Glasses of the MnNbOF5–BaF2–InF3 system were prepared. The structure, thermal behavior, and crystallization of these glasses were studied by IR and Raman spectroscopy, differential scanning calorimetry (DSC), X-ray powder diffraction, and microscopy. The ions form a mixed glass network. Glass crystallization occurs in one or two steps depending on the component ratio. The major crystal phases are Ba3In2F12 and BaNbOF5. The obtainability of transparent crystal-glass samples in MnNbOF5–BaF2–InF3 glasses via heat treatment is shown.
关键词： fluoride glasses,structure,crystallization,oxyfluoride glasses
更新于2025-09-23 15:21:21
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The effect of boron substitution for aluminium on the microstructure of calcium fluoro-aluminosilicate glasses and glass-ceramics
摘要： Calcium fluoro-aluminosilicate (4.5SiO2-3Al2O3-1.5P2O5-3CaO-2CaF2) glasses have significant applications in the medical and dental fields. However, due to the biological hazard of aluminium in the human body, this study focused on the influence of boron substitution for aluminium on the structure and properties of a series of substituted glasses and their correlated glass-ceramics. The results indicated that by increasing the amount of boron, the density of glasses and their glass-ceramics both decreased, whereas the number of bridging oxygens in the glasses increased. The glass transition temperature and the crystallization temperature remained almost unchanged for the glasses with a boron substitution of less than 25 mol%. Boron formed oxygen bridges in all glasses in the form of BO3 triangles and BO4 tetrahedra. Reducing the Al content in glasses, had an effect on the morphology and orientation of the fluorapatite crystal phase formed.
关键词： Mullite,Fluorapatite,Boron-Substitution,Calcium fluoro-aluminosilicate glasses
更新于2025-09-23 15:21:21
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Effect of Eu3+ ions on optical and fluorescence studies of Nd3+ ions doped zinc-lithium fluoroborate glasses
摘要： Nd3+ single and Nd3+/Eu3+ co-doped ZnF2-LiF-Na2CO3-Bi2O3-H3BO3, zinc lithium fluoroborate (ZLFNBiB) glasses with good optical properties have been prepared by high temperature melt-quenching method. The single and co-doped samples exhibiting emission bands centered at 874, 1058 and 1330 nm under the excitation of 808 nm laser diode (LD). The photoluminescence spectra for co-doped glasses were recorded under the 394 and 464 nm of xenon lamp as excitation sources. The Judd-Ofelt intensity parameters were calculated from optical absorption spectrum and radiative parameters from the emission spectrum of 0.5 mol% of Nd3+ doped glass. The large stimulated emission cross-section and branching ratio values are evaluated and compared with the other Nd3+ doped systems, the energy transfer from Eu3+ to Nd3+ ions is observed and thoroughly discussed from NIR emission spectra (λexc = 394 nm) of co-doped glasses. The decay profiles are recorded for all the concentrations of co-doped samples and the experimental lifetimes (τexp) were obtained from the decay profiles. The binding energy and Urbach energy values of prepared glass samples were calculated and discussed.
关键词： Spectroscopic properties,Fluorescence,Energy transfer,Lifetime.,Nd3+/Eu3+-co-doped glasses
更新于2025-09-23 15:21:21