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[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
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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
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Multi-scale process simulation for additive manufacturing through particle filled vat photopolymerization
摘要： The majority of research into vat photopolymerization (VP), has been focused on experimental investigations of the influence of process and material parameters. In a specific application of the VP technique, where the resin is filled with particles, this empirical approach has its limitations. In order to fully understand the relation between process parameters and the material properties a detailed numerical analysis is needed. In this paper we present a multi-scale and multi-physical simulation approach to unravel such relations in the complex production process. Using a homogenization approach, the influence of the filler particles, in this case alumina, on the light scattering, conversion characteristics and resulting effective thermal and mechanical properties is determined. The effective composite material and scattering properties are then used as input in a process simulation framework. This enables prediction of key filled-VP characteristics at a structural level. A mesh sensitivity analysis at the component scale reveals that adequate predictions may be obtained with a rather course discretization, facilitating multi-physics VP part simulations.
关键词： Homogenization framework,Multi-physical modeling,Process simulation,Ceramics,Additive manufacturing,Vat photopolymerization,Multi-scale modeling
更新于2025-09-23 15:19:57
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The effect of spot overlap ratio on femtosecond laser planarization processing of SiC ceramics
摘要： Silicon carbide ceramics are widely used in many fields owing to their excellent mechanical properties such as good wear resistance, thermal stability, and chemical corrosion resistance. The laser planarization processing can effectively achieve the functional, practical, and engineering process, satisfying the demands of the assembly precision. Therefore, different spot overlap ratios were utilized to investigate the effect of femtosecond laser planarization processing on silicon carbide ceramic samples. Various scanning speeds and laser repetition frequencies were matched to achieve different spot overlap ratios under the premise of fixed laser incident angle and single pulse energy. Under different parameters, the ablation depth, surface roughness, surface morphology, oxidation, and residual stress were compared. The result showed that at the same spot overlap ratio, the ablation depth and surface roughness are basically maintained at a stable value despite the difference in the scanning speed and repetition rate. The surface oxidation phenomenon remarkably decreased at the spot overlap ratio less than 90%. The decrease in the overlap ratio leads to the transition of the low frequency nano-ripple and the high frequency nano-ripple, and the surface residual stress converted from tensile stress to compressive stress. Combining processing requirements with ablation quality, the parameters are divided into three parts to fit three processes based on the spot overlap ratios. The variation in the spot overlap ratios as the guidelines had good potential in guiding the parameter range selection.
关键词： Residual stress,Spot overlap ratios,Femtosecond laser,Silicon carbide ceramics,Planarization processing
更新于2025-09-23 15:19:57
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Excellent electrostrictive coefficient in bismuth sodium titanate-based ceramics via regulating degree of diffuseness and phase composition
摘要： Herein, the strain (S) with low hysteresis can be achieved in [Bi0.5(Na0.72K0.18Li0.10)0.5]0.995Sr0.005(Ti0.995Ta0.005)O3-BaZrO3-NaNbO3 ceramics by an electrostrictive effect, and an excellent electrostrictive coefficient (Q33) of ～0.037 m4/C2 can be obtained under an electric field of 60 kV/cm. The enhancement of the degree of diffuseness regulated by phase compositions can effectively promote the electrostrictive response and increase the Q33 value. A higher ratio of P4bm and a larger Ps in P4bm guarantee the good linear relationship between S and P2 (P represents polarization), where a larger Ps (P4bm) can effectively restrict the expression of ferroelectric state with the increase of electric fields (E). Consequently, high Q33 values (0.033–0.037 m4/C2) are nearly independent of the applied electric fields. Although the strain from the electrostrictive effect is not tremendous, the good linear relationship between S and P2 is meaningful to the accurate displacement control in displacement actuators.
关键词： phase composition,degree of diffuseness,electrostrictive coefficient,bismuth sodium titanate-based ceramics
更新于2025-09-23 15:19:57
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Preparation, structural and functional properties of PbTiO3-δ ceramics
摘要： In the present study, oxygen deficient PbTiO3-d ceramics were prepared by solid state-reaction method. The formation of the pure perovskite phase with tetragonal structure was confirmed for the 800°C/2h calcined sample by using X-ray diffraction analysis at room temperature. Energy dispersive X-ray spectroscopy analyses confirm the creation of oxygen vacancies in the system for charge compensations, as demonstrated by the percentage of O atoms of ~53%. The complex impedance data reveals important contributions of the oxygen vacancies to the total dielectric response that are homogeneous distributed within the sample. The room temperature magnetic properties show a weak ferromagnetic character in all the samples that might be attributed to the oxygen vacancies defects and to surface effects.
关键词： oxygen vacancies,EDX spectra,magnetic properties,ceramics,dielectric properties
更新于2025-09-19 17:15:36
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Gel-casting of MgAl <sub/>2</sub> O <sub/>4</sub> transparent ceramics using a common dispersant
摘要： The ethanolaminic salt of citric acid (commercial name Dolapix CE 64) has commonly been used as a dispersant for colloidal based ceramic forming process. In this paper, a surprise was presented that MgAl2O4 spinel slurries consisting of MgAl2O4 spinel nanoparticles and Dolapix CE 64 gelled in air at room temperature spontaneously. The MgAl2O4 spinel slurries with high solid loading (54 vol %) were prepared with Dolapix CE 64 and the green body with up to 57 % relative density was obtained. MgAl2O4 transparent ceramics with small grain size (0.92 μm) and high transmittance (81.7 % at 600 nm) were fabricated after pre-sintering at 1500 ℃ and hot-isostatic sintering at 1550 ℃.
关键词： transparent ceramics,spinels,gelcasting,slurries
更新于2025-09-19 17:15:36
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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
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Facile microwave-assisted synthesis of Cr2O3 nanoparticles with high near-infrared reflection for roof-top cooling applications
摘要： Microwave-assisted solution synthesis was employed for the preparation of Cr2O3 nanoparticles using Cr(acac)3 and ethylene glycol. The optimum conditions for the completion of the reaction forming a green precipitate (yield-95%) were: irradiation for 40e60 min at 220 (cid:1)C solution temperature. The as-prepared sample was barely crystalline; annealing in air at above 300 (cid:1)C formed nanocrystalline Cr2O3, as shown by X-ray diffraction (XRD). High-resolution transmission electron microscopy (HRTEM) of the “700 (cid:1)C sample” con?rmed the well-crystallised Cr2O3 formation with ~37 nm average size. The as-prepared powder (bluish-green) showed high near-infrared (NIR) re?ectance, whereas the annealed samples showed bright-green re?ectance, whose International Commission on Illumination L*a*b* (CIE L*a*b*) values shifted towards the green region. The higher Dq/B value (3.76), suggested that Cr3t lies in a strong crystal ?eld. Stainless steel blocks covered with the as-prepared (intermediate) material reduced heating under sunlight by 5 (cid:1)C, indicating its suitability as an easily prepared tile coating for roof-top applications. The annealed samples are found suitable as an anti-dazzling coating for automobile windscreens and rear-view mirrors.
关键词： Chemical synthesis,Ceramics,Microwave-assisted synthesis,Oxide materials,Cr2O3 nanoparticles
更新于2025-09-19 17:15:36
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Effects of B-Site Substitution on Up-Conversion Luminescence and Ferroelectric Properties in Er3+-Doped Strontium Barium Niobate
摘要： An effective route to regulate up-conversion luminescence (UCL) and polarization properties has been developed in tetragonal tungsten bronze ferroelectrics of (Sr0.29Er0.01)Ba0.7Nb2-xMoxO6 (SBN-Ax, 0 ≤ x ≤ 0.1) and Sr0.3Ba0.7(Nb1.99-xMoxEr0.01)O6 (SBN-Bx, 0 ≤ x ≤ 0.1) ceramics. Through investigating the UCL spectra of SBN-Ax and SBN-Bx ceramics, markedly different enhancement effects of UCL intensity have been revealed which can be attributed to the peculiar structural feature of TTBs. Furthermore, temperature sensing, dielectric and ferroelectric properties have also confirmed to display B-site substitution-dependent intriguing behaviors.
关键词： ferroelectric,luminescence,Ceramics
更新于2025-09-19 17:15:36