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Additive-Manufacturing of 3D Glass-Ceramics down to Nanoscale Resolution
摘要： Fabrication of a true-3D inorganic ceramic with resolution down to nanoscale (～ 100 nm) using sol-gel resist precursor is demonstrated. The method has an unrestricted free-form capability, control of the ?ll-factor, and high fabrication throughput. A systematic study of the proposed approach based on ultrafast laser 3D lithography of organic-inorganic hybrid sol-gel resin followed by a heat treatment enabled formation of inorganic amorphous and crystalline composites guided by the composition of the initial resin. The achieved resolution of 100 nm was obtained for 3D patterns of complex free-form architectures. Fabrication throughput of 50 × 103 voxels/s is achieved; voxel - a single volume element recorded by a single pulse exposure. A post-exposure thermal treatment was used to form a ceramic phase which composition and structure were dependent on the temperature and duration of the heat treatment as revealed by Raman micro-spectroscopy. The X-ray diffraction (XRD) showed a gradual emergence of the crystalline phases at higher temperatures with a signature of cristobalite SiO2, a high-temperature polymorph. Also, a tetragonal ZrO2 phase known for its high fracture strength was observed. This 3D nano-sintering technique is scalable from nanoscale to millimeter dimensions and opens a conceptually novel route for optical 3D nano-printing of various crystalline inorganic materials de?ned by an initial composition for diverse applications for microdevices designed to function in harsh physical and chemical environments and at high temperatures.
关键词： ultrafast 3D laser nanolithography,3D nanoscale optical printing,inorganic 3D structures,high-temperature glass-ceramic materials,calcination
更新于2025-09-04 15:30:14
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Photoluminescence features of new Eu <sup>3+</sup> -doped Gd <sub/>4</sub> Mo <sub/>7</sub> O <sub/>27</sub> phosphors synthesized using glass crystallization technique
摘要： New Eu3+-doped Gd4Mo7O27 crystals (the molar ratio of Gd2O3/MoO3 = 1/3.5) with a monoclinic structure C2/c (an inversion symmetry) were synthesized through the crystallization of xEu2O3-(18.89-x)Gd2O3-66.11MoO3-15B2O3-1Al2O3 glasses (x = 0.0472 and 1.889) and photoluminescence (PL) emissions of Eu3+ ions were measured for the first time. The crystallized glass with no Eu2O3 addition (x = 0) showed a blue color under the irradiation of ultra-violet light with a wavelength of λ = 254 nm, the emitting color of the crystallized glass with x = 0.0472 was pink, and that of the crystallized glass with x = 1.889 was orange. The charge transfer (CT) of O2-→Mo6+ providing broad peaks centered at around 325 nm was observed in the crystallized glasses. The peak intensity at 591 nm for the 5D0→7F1 transition of Eu3+ ions in the crystallized glasses with x = 0.0472 and 1.889 was very close to that at 615 nm for the 5D0→7F2 transition for the excitation of λex = 394.5 nm. We propose potential of Gd4Mo7O27 as a new host crystal for rare-earth-doped phosphors.
关键词： Eu3+-doping,Glass crystallization,Photoluminescence,Phosphor,Gd4Mo7O27
更新于2025-09-04 15:30:14
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Optical temperature sensor based on Sm3+ emissions in a fluorotellurite glass
摘要： The temperature dependence of the visible luminescence of a fluorotellurite glass doped with 2.5 mol% of Sm3+ ions was studied in order to use it as a high temperature sensing probe. For this purpose, the emission intensities of the levels from 4G5/2 to 6HJ (J = 5/2, 7/2, 9/2, 11/2) transitions were measured in a temperature range from 300 up to 650 K. The changes in the emission profiles were calibrated by means of the fluorescence intensity ratio technique. The maximum temperature value obtained for the thermal sensibility was 640 K which is in the range of other matrix glasses. The calibration curve was done by fitting the intensity ratio between the different peak emissions. Finally, a schematic design for the Sm3+ optical temperature sensor is presented and the calculations of the sensitivity have been obtained. In addition, the fluorotellurite glass has been structural characterized by SEM-EDX, Raman Spectroscopy and XRD in order to infer the local environment of Sm3+ ions. Furthermore, the Judd-Ofelt parameters have been calculated from the absorption spectra and derived branching ratios and transition probabilities have been computed as well.
关键词： Material characterization,Sm3+,Thermal sensitivity,Fiber optical temperature sensor,Tellurite glass
更新于2025-09-04 15:30:14
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Microleakage of conventional light-cure resin-based fissure sealant and resin-modified glass ionomer sealant after application of a fluoride varnish on demineralized enamel
摘要： Background International guidelines on the prevention of caries recommend sealing of the pits and fissures of the permanent molars. There is no evidence on which type of material is most effective on demineralized enamel. Aim To evaluate the microleakage of a conventional light-cured, resin-based fissure sealant (LCRBS), GrandiO Seal, and a resin-modified glass ionomer sealant (RMGIS), Vitremer, after application of a fluoride varnish, Bifluorid 12, on demineralized enamel. Design 80 human third molars were divided into eight groups. The groups combined the three study factors (1) type of enamel (intact or demineralized); (2) enamel non-varnished or varnished with Biflourid12; and (3) type of sealant (GrandiO Seal or Vitremer). The percentage of microleakage after thermocycling was measured using imaging analysis software. The Kruskal-Wallis plus Dunn tests were used to compare differences in microleakage in the different groups. Results The lowest microleakage was in the unvarnished groups, and was the same for GrandiO Seal and Vitremer. When varnish was applied, microleakage was greater in demineralized enamel than in intact enamel for both LCRBS and RMGIS. Conclusion The application of fluoride varnish on demineralized enamel increases the microleakage of both GrandiO Seal and Vitremer.
关键词： microleakage,demineralized enamel,resin-modified glass ionomer sealant,fluoride varnish,light-cure resin-based fissure sealant
更新于2025-09-04 15:30:14
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Controllable competitive nanocrystallization of La3+-based fluorides in aluminosilicate glasses and optical spectroscopy
摘要： Glass ceramic has been regarded as an alternative to traditional bulk materials such as single crystal and transparent ceramic. The nucleation/growth behavior of glass ceramic via crystallization is an important topic but is seldom studied so far. In the present work, a series of La3+-based oxyfluoride aluminosilicate glasses are designed to understand their nanocrystallization processes upon heating. Impressively, controllable LaF3, α-NaLaF4 and β-NaLaF4 phase-competitive crystallization in glasses is achieved and structural/spectroscopic characterizations confirm the key role of Al/Si ratio to determine the release of Na+ ions from glass network to participate in crystallization and phase transformation. Furthermore, the developed glass ceramics are evidenced to be ideal hosts for lanthanide dopants (such as Eu3+ and Yb3+/Er3+), which can effectively incorporate into the precipitated fluoride crystal lattices by substituting La3+ ions. As a consequence, incoherent LED-excitable upconverting devices are constructed to demonstrate their promising application as emitting media in display.
关键词： Luminescence,Glass ceramics,NaLaF4,Optical materials,Upconversion
更新于2025-09-04 15:30:14
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Structure and Properties of Gallium-Rich Sodium Germano-Gallate Glasses
摘要： Glass compositions in the gallium-rich region of the ternary GaO3/2-GeO2-NaO1/2 vitreous system are studied as a function of the Na/Ga cationic ratio (ranging from 1.30 to 1.61) for a fixed GeO2 content. Glass structures are investigated by 71Ga MAS-NMR, infrared and Raman spectroscopies, and the thermal, optical and physical properties are characterized. Vibrational spectra are interpreted with the help of density functional theory (DFT) calculations. Gallium oxide generally enters the germania network in four-fold coordination, however for Na/Ga ratio below unity, gallium cations tend to charge balance with the formation of 5- or 6-fold coordination units. When the amount of sodium is greater than gallium, non-bridging oxygens (NBOs) are formed preferably on germanate tetrahedral units. These structural descriptions are used to understand the evolution of glass properties such as glass transition temperature, density and refractive index.
关键词： germano-gallate glasses,infrared,vibrational spectroscopy,glass structure,71Ga NMR spectroscopy
更新于2025-09-04 15:30:14
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Quartz-enhanced conductance spectroscopy for nanomechanical analysis of polymer wire
摘要： Quartz-enhanced conductance spectroscopy is developed as an analytical tool to investigate dynamic nanomechanical behaviors of polymer wires, in order to determine the glass transition temperature (Tg). A polymethyl methacrylate (PMMA) microwire with a diameter of 10 lm was bridged across the prongs of a quartz tuning fork (QTF). With the advantage of QTF self-sensing as compared with micro-cantilevers or other resonators, the resonance frequency and Q factor can be directly determined by means of its electrical conductance spectra with respect to the frequency of the external excitation source (dI/dV vs f), and therefore, no optical beam is required. The Tg of the PMMA microwire was determined by the maximum loss modulus of the QTF, calculated from the resonance frequency and the Q factor as a function of temperature. The measured Tg of the PMMA is 103 (cid:2)C with an error of 62 (cid:2)C. Both heating/cooling and physical aging experiments were carried out, demonstrating that the technique is both reversible and reproducible.
关键词： PMMA,polymer wire,quartz tuning fork,nanomechanical analysis,glass transition temperature,Quartz-enhanced conductance spectroscopy
更新于2025-09-04 15:30:14
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Glass transition temperature of PMMA/modified alumina nanocomposite: molecular dynamic study
摘要： In this study, the effect of alumina and modi?ed alumina nanoparticles in a PMMA/alumina nanocomposite was investigated. To attain this goal, the glass transition behavior of poly methyl methacrylate (PMMA), PMMA/alumina and PMMA/functionalized alumina nanocomposites were investigated by molecular dynamic simulations (MD). All the MD simulations were performed using the Materials Studio 6.0 software package of Accelrys. To obtain the glass transition temperature, the variation of density versus temperature was obtained. The temperature at which the slope of the density-temperature curve observably changes is de?ned as the glass transition temperature (Tg). The effect of alumina nanoparticles on the Tg was related to the free volume and the mobility of chain segments and the interaction between the alumina nanoparticles and the polymer. The mobility of the chain segments was investigated based on the mean square displacement and radius gyration. The results show that the incensement the Tg of the PMMA/functionalized alumina nanocomposite is more than that of the PMMA/alumina nanocomposite due to the modi?cation of the alumina nanoparticles.
关键词： molecular dynamic,nanocomposite,glass transition temperature,gyration radius
更新于2025-09-04 15:30:14
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Improvement in the amine glass platform by bubbling method for a DNA microarray
摘要： A glass platform with high sensitivity for sexually transmitted diseases microarray is described here. An amino-silane-based self-assembled monolayer was coated on the surface of a glass platform using a novel bubbling method. The optimized surface of the glass platform had highly uniform surface modifications using this method, as well as improved hybridization properties with capture probes in the DNA microarray. On the basis of these results, the improved glass platform serves as a highly reliable and optimal material for the DNA microarray. Moreover, in this study, we demonstrated that our glass platform, manufactured by utilizing the bubbling method, had higher uniformity, shorter processing time, lower background signal, and higher spot signal than the platforms manufactured by the general dipping method. The DNA microarray manufactured with a glass platform prepared using bubbling method can be used as a clinical diagnostic tool.
关键词： glass platform,bubbling method,self-assambled monolayer,DNA microarray
更新于2025-09-04 15:30:14
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Achieving enhanced pH sensitivity using capacitive coupling in extended gate FET sensors with various high-K sensing films
摘要： Sensing properties of various high-k sensing membrane, such as SnO2, HfO2, ZrO2, and Ta2O5, in dual gate extended-gate field-effect transistor (EGFET) were investigated. By adapting the dual-gate structure, high sensitivity exceeding the conventional Nernstian limit on sensitivity (59.15 mV/pH at 25 °C) was realized due to capacitive coupling effect. As a results, it was confirmed that dual-gate EGFET with Ta2O5 sensing membrane which has high permittivity shows the highest sensitivity of 478.0 mV/pH as well as excellent hysteresis voltage and drift rate characteristics.
关键词： Glass EG detector,Dual gate poly-Si TFT transducer,High-k membrane,Highest sensitivity,Capacitive coupling,EGFET pH sensor
更新于2025-09-04 15:30:14