Fused Silica Research Articles

Enhanced radiation resistance of Er3+/Yb3+ co-doped high-phosphorus silica glasses and fibers via phase-interface engineering

Enhanced radiation resistance of Er3+/Yb3+ co-doped high-phosphorus silica glasses and fibers via phase-interface engineering

Effect of dielectric material on the uniformity of nanosecond pulsed dielectric barrier discharge

Dielectric barrier discharge (DBD) is considered as a promising technique to produce large volume uniform plasma at atmospheric pressure, and the dielectric barrier layer between the electrodes plays a key role in the DBD processes and enhancing discharge uniformity. In this work, the uniformity and discharge characteristics of the nanosecond (ns) pulsed DBD with dielectric barrier layers made of alumina, quartz glass, polycarbonate (PC), and polypropylene (PP) are investigated via discharge image observation, voltage-current waveform measurement and optical emission spectral diagnosis. Through analyzing discharge image by gray value standard deviation method, the discharge uniformity is quantitatively calculated. The effects of the space electric field intensity, the electron density (N e), and the space reactive species on the uniformity are studied with quantifying the gap voltage U g and the discharge current I g, analyzing the recorded optical emission spectra, and simulating the temporal distribution of N e with a one-dimensional fluid model. It is found that as the relative permittivity of the dielectric materials increases, the space electric field intensity is enhanced, which results in a higher N e and electron temperature (T e). Therefore, an appropriate value of space electric field intensity can promote electron avalanches, resulting in uniform and stable plasma by the merging of electron avalanches. However, an excessive value of space electric field intensity leads to the aggregation of space charges and the distortion of the space electric field, which reduce the discharge uniformity. The surface roughness and the surface charge decay are measured to explain the influences of the surface properties and the second electron emission on the discharge uniformity. The results in this work give a comprehensive understanding of the effect of the dielectric materials on the DBD uniformity, and contribute to the selection of dielectric materials for DBD reactor and the realization of atmospheric pressure uniform, stable, and reactive plasma sources.

Elucidating the roles of electrolytes and hydrogen bonding in the dewetting dynamics of the tear film

This study explores the impact of electrostatic interactions and hydrogen bonding on tear film stability, a crucial factor for ocular surface health. While mucosal and meibomian layers have been extensively studied, the role of electrolytes in the aqueous phase remains unclear. Dry eye syndrome, characterized by insufficient tear quantity or quality, is associated with hyperosmolality, making electrolyte composition an important factor that might impact tear stability. Using a model buffer solution on a silica glass dome, we simulated physiologically relevant tear film conditions. Sodium chloride alone induced premature dewetting through salt crystal nucleation. In contrast, trace amounts of solutes with hydroxyl groups (sodium phosphate dibasic, potassium phosphate monobasic, and glucose) exhibited intriguing phenomena: quasi-stable films, solutal Marangoni-driven fluid influx increasing film thickness, and viscous fingering due to Saffman-Taylor instability. These observations are rationalized by the association of salt solutions with increased surface tension and the propensity of hydroxyl-group-containing solutes to engage in significant hydrogen bonding, altering local viscosity. This creates a viscosity contrast between the bulk buffer solution and the film region. Moreover, these solutes shield the glass dome, counteracting sodium chloride crystallization. These insights not only advance our understanding of tear film mechanics but also pave the way for predictive diagnostics in dry eye syndrome, offering a robust platform for personalized medical interventions based on individual tear film composition.

Chiral nematic composite coatings as a visual detection platform for formic acid with anti-water interference

Formic acid is an important industrial chemical but is toxic and corrosive. To benefit its qualified use and to avoid corrosion or injury from touching, rapid, portable and sensitive on-site sensing of formic acid is thus of considerable importance. Here, a photonic crystal coating sensor for formic acid visual detection is fabricated through the mild co-assembly of both biomass-based cellulose nanocrystals (CNCs) and hydroxypropyl-β-cyclodextrin (HPCD) on a quartz glass slide. Further surface modification by hexadecyltrimethoxysilane (HTDMS) with low surface energy significantly overcomes the inherent water intolerance of the CNC-HPCD composite while maintaining its chiral nematic structure. The resulting hydrophobic CNC-HPCD (H-CNC) sensing slide shows a distinct and rapid structural color change after formic acid stimulation, realizing the formic acid detection by naked eye. By virtue of its stable and repeatable water resistance, the H-CNC sensing slide enables the specific colorimetric detection of formic acid in water-containing environments for qualitative and even quantitative purposes. This study suggests that H-CNC has the potential to act as a high-performance sensing platform that is useful for the colorimetric detection of formic acid in some industrial products.

Investigation of the thermal conductivity of SiO2 glass using molecular dynamics simulations

AbstractA recent study showed that generating local crystalline paths within a glassy matrix provides only a moderate increase in thermal conductivity until the path fills most of the total volume. It was indicated that percolation theory governs the thermal conductivity in such crystalline‐implanted glass composites. In this study, we use computer simulations to investigate the effect of partial vitrification by breaking structural order of silica crystals by local vitrification. Such locally vitrified crystal structures are made by the bond‐transposition method, where the extent of vitrification can be tuned. Also, we test melt‐quenching of three SiO2 crystalline structures (α‐quartz, coesite, and stishovite) to make silica glasses with different densities. The cooling rates and pressures were varied during the melting process in order to obtain glass structures with varied degrees of order. Our results show that the thermal conductivity of silica glasses calculated using Green–Kubo relation decreases rapidly as soon as the crystallinity is disturbed by bond transition or generated local glassy phase. This implies the phonon mean free path rapidly shrinks with even a small number of scatterers, regardless of the original polymorph. Through the investigation of the pressure effect, a strong proportional relation between the thermal conductivity and the density is found among all silica samples. Such correlation can be accounted by assuming a constant integral term in the Green–Kubo relation without the volume scaling, which is reasonable based on a weak dependence of κV on the density of silica glass except with a slight increase at low quench pressures. We hypothesize that when the quench pressure increases moderately, an increase of characteristic ring size tends to generate a more flexible SiO2 structure which results more phonon scattering. Green–Kubo modal analysis further shows that the contribution from modes at low frequencies is suppressed when SiO2 is melt‐quenched at higher pressure and vice versa.

Structure evolution of the silica glass under the vibration field through molecular dynamics simulations

AbstractSilica glass has found wide applications, including space shuttle windows, optical fibers, and deep ultraviolet light lens elements, due to its excellent optical, electrical, and mechanical properties. However, understandings of its structure change under the vibration field are limited in literature. In this work, the structure of silica glass and its behavior under the vibration field have been investigated through molecular dynamics simulations. The short and medium‐range structures, including coordination number, Qn species distribution, pair distribution function, and bond angle distribution, were analyzed. It was found that the overall and local structures of silica glass showed periodic changes under the vibration field. The root‐mean‐square displacements as well as the kinetic energies of the atoms in the system were further analyzed. The results show that there is a periodic transformation of kinetic and potential energies. In addition, the kinetic energy decreases and is converted into the thermal energy during the vibration, which is confirmed by the increase of the system temperature. This can explain the thermoelastic loss mechanism in energy dissipation from literature. This work reveals the structure evolution and energy change of glass under the vibration field from atomistic level, which provides important understandings for related researches.

Research on additive manufacturing technology of high solid loading silica glass slurry

In this work, digital light processing (DLP) 3D printing technology was used to fabricate transparent silica glass with complex structures. The effects of different particle sizes and mixing ratios of silica powders on the viscosity of the prepared slurries were investigated. The results showed that when 100–200 nm and 800 nm silica powders were mixed in a 1:4 vol ratio, the slurry exhibited the lowest viscosity. The highest solid loading of the slurry prepared with this mixed silica powder reached 75 wt%, with a viscosity of only 1245 mPa·s. The high solid loading slurry was subjected to 3D printing, debinding, and sintering treatment, and the transparent silica glass samples with complex structures was obtained.

Compressive failure and fragmentation of fused silica glass under quasi-static loading

This paper investigates the failure and post-failure fragmentation processes of fused silica glass cylinders under quasi-static compression, addressing the effects of surface finish on apparent strength. The compressive strengths of cylinders with side-polished sides under dry friction conditions (PSG-D) or lubricated conditions (PSG-L) were 2.52 GPa and 2.32 GPa, respectively. In situ observations showed that these specimens fractured from either the top or bottom contact surfaces, and that friction between the specimen and the loading anvil delayed the development of surface cracks. The unpolished rough side specimens (RSG-D) under dry friction conditions failed at a much lower level of 1.54 GPa, initiated by defects in the side surfaces. Specimens "explosively" fragmented upon failure. The propagation speed of the failure front ranged from 1800 to 2800 m/s. The average sizes and distributions of the fragments were determined through statistical analysis, with results showing reasonably close agreement with theoretical estimations.

Revealing Subsurface Damage Morphology and Patterns in areal Ultrashort Pulse Laser Machining of Glass

Material removal rates as well as surface and subsurface quality are key aspects for the industrial application of ultrashort pulse (USP) laser machining. However, revealing so-called subsurface damage (SSD) is challenging. The presented study visualizes and quantifies subsurface damage patterns in areal USP laser ablation of fused silica (FS) and glass N-BK7 (BK). For the first time, using high-resolution optical coherence tomography (OCT) as non-destructive and three-dimensional (3D) evaluation method, SSD morphologies of areal laser machining induced damages are analysed. Influences of laser wavelength, beam geometry and processed material are investigated. Discovered differences of damage morphologies and depth in FS and BK point out the relevance of selecting suitable process parameters. Based on the evaluation of volumetric OCT data, the authors were able to quantify damage morphologies using the surface texture ratio as well as power spectral density functions. One important finding for the quantification and comparability of damage depths in USP laser processing is the influence of applicable evaluation thresholds. In comparison to area thresholds of 0.001% being applicable to OCT measurements, more lenient thresholds of e.g. 1% commonly applied in destructive SSD measurement methods in average result in a reduction of measured damage depths by a factor of ~ 2. This potentially leads to an underestimation of damage depths depending on methods on thresholds used. The presented measurement and evaluation methods as well as gained process insights are important assets for the future optimization of low-damage USP laser micromachining of brittle materials. Moreover, the general applicability and relevance of OCT-based morphological damage analysis in laser material processing is shown.

Development of conductive carbon-based interdigitated electrode array integrated with microfluidic channel for blood glucose sensing

PurposeThis study aims to provide a microfluidic blood glucose sensing platform based on integrated interdigitated electrode arrays (IDEAs) on a flexible quartz glass substrate, adhering closely to pertinent electrochemical characterizations.Design/methodology/approachSensors are the key elements of the modern electronics era through which all the possible physical quantities can be detected and converted into their equivalent electrical form and processed further. But to make the sensing environment better, various types of innovative architectures are being developed nowadays and among them interdigitated electrodes are quite remarkable in terms of their sensing capability. They are a well-qualified candidate in the field of gas sensing and biosensing, but even their sensitivities are getting saturated due to their physical dimensions. Most of the thin film IDEAs fabricated by conventional optical lithographic techniques do not possess a high surface-to-volume ratio to detect the target specified and that reduces their sensitivity factor. In this context, a classic conductive carbon-based highly sensitive three dimensional (3D) IDEA-enabled biosensing system has been conceived on a transparent and flexible substrate to measure the amount of glucose concentration present in human blood. 3D IDEA possesses a way better capacitive sensing behavior compared to conventional thin film microcapacitive electrodes. To transmit the target biological analyte sample property for the detection purpose to the interdigitated array-based sensing platform, the design of a microfluidic channel is initiated on the same substrate. The complex 3D Inter Digital array structure improves the overall capacitance of the entire sensing platform and the reactive surface area as well. The manufactured integrated device displays a decent value of sensitivity in the order of 5.6 µA mM−1 cm−2.FindingsDevelopment of a low-cost array-based integrated and highly flexible microfluidic biochip to extract the quantity of glucose present in human blood.Originality/valuePotential future research opportunities in the realm of integrated miniaturized, low-cost smart biosensing systems may arise from this study.

Bismuth-Doped Fiber Lasers and Amplifiers Operating from O- to U-Band: Current State of the Art and Outlook

The development of unique optical materials that provide amplification and lasing in new wavelength ranges is a major scientific problem, the solution of which is becoming the basis for the emergence of new optical technologies, which are primarily targeting the expanding of operating wavelengths in silica glass. In fact, one of the notable advances in the field of fiber optics over the past two decades has been the production of a new type of laser-active fibers (namely bismuth-doped fibers), which has made it possible to cover previously inaccessible (for rare-earth-doped fibers) spectral ranges, in particular O-, E-, S-, and U-telecom bands. The advance in this direction has led to further growth of the technological capabilities in the telecom industry for amplification and generation of optical radiation in various wavelength bands, which will result in the near future to overcoming the problem known as “capacity crunch” by means of expanding the data transmission range. Recently, bismuth-doped fibers have been actively studying in order to improve their characteristics, which would allow for efficient implementation of optical devices based on bismuth-doped fibers (BDFs) with deployed telecommunications systems. This is one of the dynamically developing areas, where progress has already manifested in form of emergence of new achievements, in particular commercially available various types of BDFs, as well as a series of novel fiber-optic amplifiers for the O- and E-bands. In this review, a number of scientific studies that have already led to a noticeable progress in the field of optical properties of BDFs and the practical implementation of optical devices (lasers and amplifiers) based on them are presented and discussed, with much attention to the achievements of recent years.

Experimenting the effectiveness of waste materials in improving the compressive strength of plastic-based mortar

The reduction in compressive strength (CS) of cementitious composites incorporating waste plastic is the main concern limiting its applicability in the building sector. Using industrial wastes as cement substitutes to enhance the CS of plastic mortar is a sustainable approach. This study used fine powdered waste materials such as silica fume (SF), marble powder (MP), and glass powder (GP) in plastic-based mortar for their effectiveness in enhancing CS. Plastic mortar specimens were cast using plastic waste in 5–25 % contents as sand replacement by mass, and their 28-day CS was recorded as a reference. SF, GP, and MP were utilized in plastic mortar mixtures separately in proportions of 5–25 %, with a 5 % increment, substituting cement by mass. These waste powders were also used in combinations of two (SF+GP, SF+MP, and GP+MP) and three (SF+GP+MP) in plastic mortar mixtures. Moreover, prediction models were built using the experimental database for the CS of plastic mortar. Gradient boosting and bagging ensemble machine learning (ML) techniques were chosen for model development. The decrease in CS was limited by substituting SF, GP, and MP for cement in plastic mortar. It was determined that the most effective substitution levels for SF, GP, and MP in plastic mortar, according to the strength enhancement, were 15, 10, and 15 wt.% of cement, respectively. The ML models closely matched experimental results, and in terms of R2 and error evaluations, bagging model outputs were more accurate than gradient boosting. The gradient boosting and bagging models had R2 of 0.89 and 0.94, respectively, with average absolute errors of 0.87 and 0.65 MPa.

Experimental study on the keyhole dynamic evolution and porosity formation during laser welding of Ti-6Al-4V alloy

Keyhole dynamic evolution significantly affects laser welding quality. For observing the keyhole’s dynamic behaviors directly, a sandwich workpiece that consists of a piece of quartz glass and a piece of Ti-6Al-4V alloy is used in experiments of this study, and the dynamic behaviors of the keyhole are recorded with a high-speed camera. The experimental results show that, in the first 5 ms of welding, the depth and width of the keyhole increase linearly and, at about 70 ms, a relatively stable keyhole is formed. A keyhole typically exhibits the shape of a “7” character in a short period after it forms. At this stage, the laser beam is reflected by the wall of the keyhole repeatedly until it reaches the bottom, which results in some tiny pore formations in the middle part of the keyhole. In subsequent welding, the collapsing and rebuilding process of the keyhole are observed, and big pores are formed at the bottom of the keyhole. The results of this research are helpful to understand the mechanism of the keyhole dynamic evolution and porosity formation during titanium alloy laser welding.

Phase Separation of ϵ‐Fe2O3 and BaFe12O19 in a Synthesis Combining Reverse‐Micelle and Sol‐Gel Techniques

AbstractEpsilon iron oxide (ϵ‐Fe2O3) and magnetoplumbite barium ferrite (BaFe12O19) are well‐known hard ferrites. For one synthesis method of ϵ‐Fe2O3, combining reverse‐micelle and sol‐gel techniques, Ba ions are used to accelerate the formation of nanorod‐shaped ϵ‐Fe2O3. On the other hand, in synthesis of BaFe12O19 both Ba and Fe ions are used to form the final product. However, the coexistence of these two ferrites has not been reported by any synthesis. Herein, we investigated the effect of Ba ions on the final product for the synthesis combining reverse‐micelle and sol‐gel techniques. At a low Ba ion ratio of [Ba]/[Fe]=0.2, ϵ‐Fe2O3 nanorods are formed, while at higher Ba ion ratios ([Ba]/[Fe]=0.4, 1, 2), BaFe12O19 appears. The phase diagram at 1000 °C shows that at a Ba ion ratio of [Ba]/[Fe]=1, the ratio of ϵ‐Fe2O3 and BaFe12O19 is almost 1 : 1. The diagram shows intermediates between these two phases do not form, indicating a phase separation of ϵ‐Fe2O3 and BaFe12O19. During the sintering process of this synthesis, initially perovskite‐type Ba2Fe2O5 and γ‐Fe2O3 nanoparticles form. Then, in areas where γ‐Fe2O3 nanoparticles are gathered around Ba2Fe2O5 and react, BaFe12O19 is formed, whereas in areas lacking Ba2Fe2O5, ϵ‐Fe2O3 nanorods are formed within Ba‐ion containing silica glass.

Nd3+-doped double-clad fluoro-sulfo-phosphate fiber for a compact kilohertz-linewidth single-frequency laser

The utilization of single-frequency fiber lasers spans critical domains including gravitational wave detection, coherent optical communication, and atomic physics. Glass fibers doped with rare earth ions serve as pivotal gain media for them, and the quest for advanced fiber matrices is paramount. Herein, a newly developed Nd3+-doped AlF3-Na2SO4-KPO3-Zn(PO3)2 glass is reported. The glass showcases exceptional attributes including high anti-crystallization stability (>150∘C), elastic modulus (75 GPa), chemical durability (8.1×10−7g⋅cm−2⋅min−1), Nd3+ concentration (>1020ions/cm3), broad effective linewidth (45 nm), and extended lifetime (465 µs), surpassing those of conventional silica and phosphate glasses. Moreover, a custom-designed double-clad Nd3+-doped fiber with a net gain coefficient of 3.2 dB/cm at 1064 nm is fabricated, and single-frequency laser output with a narrow linewidth of 11 kHz has been obtained utilizing a 1.4-cm-long fiber, indicating the potential of this fiber as a promising gain medium for ultra-narrow-linewidth single-frequency fiber lasers.

Sub-Micron Replication of Fused Silica Glass and Amorphous Metals for Tool-Based Manufacturing.

The growing importance of submicrometer-structured surfaces across a variety of different fields has driven progress in light manipulation, color diversity, water-repellency, and functional enhancements. To enable mass production, processes like hot-embossing (HE), roll-to-rollreplication (R2R), and injection molding (IM) are essential due to their precision and material flexibility. However, these processes are tool-based manufacturing (TBM) techniques requiring metal molds, which are time-consuming and expensive to manufacture, as they mostly rely on galvanoforming using templates made via precision microlithography or two-photon-polymerization (2PP). In this work, a novel approach is demonstrated to replicate amorphous metals from fused silica glass, derived from additive manufacturing and structured using hot embossing and casting, enabling the fabrication of metal insets with features in the range of 300nm and a surface roughness of below 10nm. By partially crystallizing the amorphous metal, during the replication process, the insets gain a high hardness of up to 800 HV. The metal molds are successfully used in polymer injection molding using different polymers including polystyrene (PS) and polyethylene (PE) as well as glass nanocomposites. This work is of significant importance to the field as it provides a production method for the increasing demand for sub-micron-structured tooling in the area of polymer replication while substantially reducing their cost of production.

Hydrothermal Dissolution of Reactive Silica Materials in Sodium Hydroxide Lyes

AbstractReactive silica materials like vitreous silica or cristobalite were dissolved at temperatures between 100 and 220 °C for up to 7 days in NaOH lyes. The liquid and solid reaction products were analyzed chemically. Sodium water glasses with silica concentrations of up to 27 wt % and molar SiO2/Na2O ratios of up to 3.7 were obtained. The experimental data were evaluated by an approximation algorithm. The initial size reduction rates ranged between 0.1 and 7 µm h−1, depending on the temperature and the choice of starting materials. Correlations between thermodynamics and kinetics were discussed.

Preparation of Langmuir-Blodgett Films from Quinoxalines Exhibiting Aggregation-Induced Emission and Their Acidochromism.

The development of aggregation-induced emission (AIE)-exhibiting compounds heavily relies on our evolving comprehension of their behavior at interfaces, an understanding that still remains notably limited. In this study, we explored the preparation of two-dimensional (2D) sensing films from 2,3-diphenylquinoxaline-based diazapolyoxa- and polyazamacrocycles displaying AIE via the Langmuir-Blodgett (LB) technique. This systematic investigation highlights the key role of the heteroatom-containing tether of 2,3-diphenylquinoxalines in the successful fabrication of Langmuir layers at the air-water interface and the transfer of AIE-emitting supramolecular aggregates onto solid supports. Using both diazapolyoxa- and polyazamacrocycles, we prepared AIE-exhibiting monolayer films containing emissive supramolecular aggregates on silica, mica, and quartz glass and characterized them using ultraviolet-visible (UV-vis) and photoluminescence (PL) spectroscopies, atomic force microscopy (AFM) imaging, and fluorescence microscopy. We also obtained multilayer AIE-emitting films through the LB technique, albeit with increased complexity. Remarkably, by employing the smallest macrocycle N2C3Q, we successfully prepared LB films suitable for the visual detection of acidic vapors. This sensing material, which contains a much lesser amount of organic dye compared with traditional drop-cast films, can be regenerated and utilized for real-life sample analysis, such as monitoring the presence of ammonia in the air and the freshness of meat.

Manufacturing fused silica hemispherical resonators using polymer glass suspension and replication molding

This work introduces a new method for manufacturing fused silica (FS)-based hemispherical resonators (HSRs) using a printable polymer glass mixture and replication molding. This process involves 3D printing to create the mold, followed by the casting of a photo-reactive pre-polymer glass mixture. This technique allows us to produce complex 3D geometries and offers faster production of resonators compared to other traditional methods. In this study, we manufactured three devices and successfully identified resonance modes with two (N = 2), three (N = 3) and four (N = 4) nodes/antinodes in all three HSRs, demonstrating the repeatability of our new manufacturing method. The highest quality factor of 482 k was achieved for the N = 3 resonance mode using the ring-down method. Some of the key advantages of our method include producing multiple devices efficiently with relatively good surface quality, making it a viable option for producing high-precision devices in the future. Our new fabrication technique results in a device surface roughness of ∼100 nm (measured over an area of 250 μm × 250 μm) and manufacturing yield of over 90%. Moreover, all the steps involved in this method can be completed outside of a specialized cleanroom environment.

Effect of magnetron sputtering power on the properties of the AlO X monolayer and AlO X /MgF2 bilayer anti-reflection films

The AlO X monolayer anti-reflection (MLAR) films and the AlO X /MgF2 bilayer anti-reflection (BLAR) films were deposited on high-purity glasses with magnetron sputtering. We investigated the influences of sputtering power on the O/Al molar ratio, microstructure, and optical properties of the AlO X MLAR films and AlO X /MgF2 BLAR films. The results showed that a too high or a too low sputtering power was detrimental to the preparation of the high-quality films, which could only be obtained when the sputtering power was 115 W. However, the sputtering power did not affect the crystallinity of the films, all of which were amorphous. When the sputtering power was 115 W, the high-purity AlO X MLAR film exhibited an O/Al molar ratio of 2.27:1, a refractive index of 1.426, and an average transmittance (T avg: average transmittance of the quartz glass deposited the film, hereinafter the same) of 94.03% within 300–1100 nm wavelength range. The T avg of AlO X /MgF2 BLAR film with a power of 115 W was 94.99%, which was 1.92% higher than that of the glass substrate. And it improved the cell’s photoelectric conversion efficiency (PCE) by 3.19%.