Transparent Materials Research Articles

Glass catfish inspired subaquatic abrasion-resistant anti-fouling window fabricated by femtosecond laser electrodeposition

Abstract Transparent materials utilized as underwater optical windows are highly vulnerable to various forms of pollution or abrasion due to their intrinsic hydrophilic properties. This susceptibility is particularly pronounced in underwater environments where pollutants can impede the operation of these optical devices, significantly degrading or even compromising their optical properties. The glass catfish, known for its remarkable transparency in water, maintains surface cleanliness and clarity despite exposure to contaminants, impurities abrasion, and hydraulic pressure. Inspired by the glass catfish's natural attributes, this study introduces a new solution named subaquatic abrasion-resistant and anti-fouling window (SAAW). Utilizing femtosecond laser ablation and electrodeposition, the SAAW is engineered by embedding fine metal bones structures into a transparent substrate and anti-fouling sliding layer, akin to the sturdy bones among catfish’s body. This approach significantly bolsters the window's abrasion resistance and anti-fouling performance while maintaining high light transmittance. The sliding layer on the SAAW’s surface remarkably reduce the friction of various liquid, which is the reason that SAAW owns great anti-fouling property. The SAAW demonstrates outstanding optical clarity even after enduring hundreds of sandpaper abrasion, attributed to the fine metal bone structures bearing all external forces and protect the sliding layer of SAAW. Furthermore, it exhibits exceptional resistance to biological adhesion and underwater pressure. In a green algae environment, the window remains clean with minimal change in transmittance over one month. Moreover, it retains its wettability and anti-fouling properties when subjected to a depth of 30 meters of underwater pressure for 30 days. Hence, the SAAW prepared by femtosecond laser ablation and electrodeposition presents a promising strategy for developing stable optical windows in liquid environments.

Experimental study on interaction characteristics of explosive cracks under confining pressure and its comparison with free boundary results

The influence of confining pressure on the dynamic fracture mechanical behavior of deep rock masses is crucial in the exploitation of deep resources and the development of underground spaces. In this study, dynamic caustics experiments were conducted using transparent epoxy resin materials to investigate the crack propagation behavior and interaction mechanisms of double cracks under confinement. The experimental results indicate that biaxial confining pressure suppresses crack propagation, interaction between double cracks, and penetration. Without confining pressure, cracks do not penetrate until the relative vertical distance ΔH between crack tips is 20 mm, whereas with confining pressure, cracks cease to penetrate when the relative vertical distance between crack tips is 10 mm; however, interaction between crack tips still exists at this point. During the crack interaction stage, both fracture toughness and propagation velocity of crack tips exhibit significant fluctuations under no confining pressure conditions, whereas under confining pressure, both decrease rapidly. Additionally, under confining pressure conditions, the fluctuation range of crack propagation direction during crack interaction is relatively small. Confining pressure rapidly reduces the degree of stress concentration at crack tips, increases the rate of energy release at crack tips, and enhances the ability of dynamic cracks to resist the influence of other crack tips or crack surfaces. Under confining pressure, continuous Rayleigh waves are typically observed at crack tips due to an imbalance between stored strain energy and the energy release rate. These waves dissipate part of the strain energy, promoting crack deflection and branching.

Highly Refractive Transparent Half‐Heuslers for Near Infrared Optics and Their Material Design

AbstractAdvanced control of light focusing, reflection, and transmission is possible with highly refractive transparent materials; however, such materials are difficult to discover because of the negative correlation between the refractive index and the optical band gap. This study elucidates half‐Heuslers as highly refractive transparent materials, considering their densely packed crystal structures comprising both covalent and ionic bonds with d orbitals. Theoretical calculations revealed that 22 ternary half‐Heusler systems (αβγ) exhibited higher refractive indices with wider band gaps than conventional high‐refractive‐index‐transparent materials in the near‐infrared region. The key to achieving a high index and wide gap is aligning α‐d and β‐d levels within a small lattice frame given by small γ elements to the verge of forming Γ‐point conduction band minimum. Experimental examinations revealed that α and γ elements with low and high melting points are preferred for the thin‐film preparation of the well‐ordered half‐Heuslers. Highly refractive transparent half‐Heuslers and their material designs expedite post‐silicon technology for controlling near‐infrared light.

Investigation on internal evolution process of slope under seismic loading: insights from a transparent soil test and shaking table test

Earthquakes are a primary factor in triggering slope instability and pose a serious threat to transportation. However, current research on the internal deformation of slopes under seismic loading remains limited. To investigate the effects of different seismic loadings on the evolution process and failure mode of slopes, a novel experiment combining transparent soil materials and shaking table tests was proposed in this study. Using a self-designed shaking table system, sine waves with amplitudes of 0.10 g, 0.15 g, and 0.20 g and frequencies of 3 Hz, 5 Hz, and 8 Hz were applied. Based on Particle Image Velocimetry (PIV) technology and non-intrusive monitoring techniques, displacement and velocity contour maps, whole-field average displacement and failure mechanism of the slope were analyzed. The results show that, as the vibration persists, the slope transitions from initial shallow linear sliding to overall circular arc sliding, exhibiting an obvious progressive traction failure mode. The evolution process of the slope could be divided into three phases: shallow low-speed sliding phase, overall rapid sliding phase, and overall low-speed sliding phase. Furthermore, the amplitude of seismic loading has a greater influence on slope deformation compared to its frequency. This novel experiment offers important insights into the internal evolution process of slopes under seismic loading.

Micro-welding of non-optical contact sapphire/metal using Burst femtosecond laser

Recently, welding of dissimilar material, such as transparent material to metal material, is widely used in aerospace, microelectronic packaging, medicine, etc. Ultrafast laser welding provides a new method for high-performance dissimilar material welding, in which the non-optical contact dissimilar material welding has become a new research hot spot. In this paper, we report the effective welding of Fe-36Ni with roughness as high as 1.1 µm to sapphire, which, to our knowledge, is the roughest dissimilar material welding achieved in ultrafast laser. A 238 fs, 1035 nm, 200 kHz Burst mode femtosecond laser (4 sub-pulses with a total energy of 132.5μJ) yields a smooth and uniform interface with a welding strength up to 11 MPa. In this context, the welding performance and mechanism of Burst mode and single pulse mode ultrafast laser are systematically analyzed. The relevant research results are expected to provide theoretical guidance for the welding of high-strength and high-stability dissimilar materials.

Micro-cracks generation and growth manipulation by all-laser processing for low kerf-loss and high surface quality SiC slicing

Low kerf-loss and high surface quality silicon carbide (SiC) wafer slicing is key to reducing cost, improving productivity, and extending industrial applications. In this paper, a novel all-laser processing approach is proposed by combining laser micro-cracks generation and growth manipulation. The first high fluence pulsed laser is applied to generate micro-cracks inside SiC, which increases its laser energy absorption. The second low fluence pulsed laser achieves the manipulation of micro-cracks growth and interconnection to separate SiC wafer. The optimal laser processing parameters are obtained to separate a 4H-SiC substrate at a thickness of 500 µm. The sliced surface is clean with average surface roughness (Sa) of 186 nm, standard deviation of 0.037, and kerf-loss of 915 nm. This laser slicing approach can be applied for high-hardness transparent material separation.

Angle-insensitive all-optical diodes in a large range of incidence by photonic heterostructure containing hyperbolic metamaterials

We theoretically and systematically investigate angle-insensitive all-optical diodes using photonic heterostructures composed of different one-dimensional photonic crystals containing hyperbolic metamaterials. Hyperbolic metamaterials comprise metals with high nonlinear coefficients and transparent dielectrics. The results indicate that the photonic heterostructure shows angle insensitivity in transmittance, transmission contrast, and the critical intensity of the threshold over a large range of incidence, achieving a high transmission contrast of approximately 0.93 between forward and backward incident light. This angle insensitivity originates from the phase-variation compensation effect in a basic unit composed of hyperbolic metamaterials and transparent dielectric materials under TM polarization. These results provide important reference values for future experiments.

Noise reducing elements filled with laminated safety glass (LSG) for use along railway lines

The main purpose of noise barriers is to shield the environment from unwanted sound. Along railway lines, noise barriers must also meet strict requirements for structural integrity, usability and fatigue safety. Furthermore, noise barriers should satisfy aesthetic criteria. Transparent noise barriers have less impact on the environment and are more widely accepted by the public. In Germany, PMMA (acrylic glass) is currently the only transparent material approved for railway noise reducing elements. Laminated safety glass (LSG) could be a viable alternative due to its high rigidity and transparency, comparatively low dirt accumulation and high chemical and physical resistance. However, it still needs to be demonstrated that LSG meets the strict requirements for use along railway lines. LSG is a type of laminated glass that has a splitter-binding intermediate layer of plastics. The multi-layered structure presents challenges regarding the proof of usability. MFPA Leipzig GmbH was commissioned by the German Centre for Rail Traffic Research at the Federal Railway Authority to develop and evaluate possible methods to prove the usability of LSG for noise barriers along railway lines. The paper presents the structure of the project, the main findings until now and the open challenges to be addressed.

Achieving coaxial photoacoustic/ultrasound dual-modality imaging by high-performance Sm: 0.72PMN-0.28PT transparent piezoelectric ceramic

As a promising new medical imaging method, photoacoustic imaging (PAI) has the advantages of optical resolution and acoustic depth of penetration. The transparent ultrasound transducer (TUT), as a novel device applied to PAI, can combine the laser and acoustic beam coaxially to improve the imaging quality. Transparent piezoelectric materials are the key to developing piezoelectric TUTs. However, due to the birefringence and light scattering caused by ferroelectric domains, it is very hard to prepare transparent piezoelectric materials with both high optical transmittance and excellent piezoelectricity. In this study, 2.5mol% Sm-doped 0.72Pb(Mg1/3Nb2/3)O3-0.28PbTiO3 (PMN-PT) ceramic with a piezoelectric coefficient d33 of 1460 pC N-1 and an optical transmission of 69% at Near-Infrared (NIR) is successfully prepared, and its optical, microstructure, ferroelectric and dielectric properties are fully studied. Subsequently, a 3 mm-diameter photoacoustic coaxial probe is fabricated, involving a transparent ultrasound transducer based on the prepared ceramic. The TUT has a center frequency (fc) of 18.5MHz, a −6dB bandwidth of 20%, and a high effective electromechanical factor (keff) of 0.62. In addition, the imaging capability of the miniature probe is firstly confirmed through PA/US dual-modality imaging of in-vivo animals and phantoms, which indicates that the proposed transparent piezoelectric ceramic has great potential for photoacoustic/ultrasound imaging.

PI-SiO2 aerogel as a versatile high transparent material for photothermal cooperative management

Effectively insulating against excessive heat generated by sunlight while also avoiding harmful ultraviolet (UV) and maintaining suitable levels of visible light transparency is vital for minimizing energy consumption and optimizing sunlight utilization. To address the challenge of photothermal collaborative management, the PI consisted of high fluorinated dianhydride and aliphatic diamine was used to effectively improve the performance of SiO2 aerogels. The resulting PI-SiO2 aerogels retain the characteristics of SiO2 aerogels, such as low density, high transparency between 82∼89 %, and excellent thermal insulation properties with an ultralow thermal conductivity range from 0.023 W/(m.K) to 0.028 W/(m.K). Meanwhile, the coarsened skeleton of aerogels can withstand the extreme temperature difference between −196 ℃ and 200 ℃ without brittle fracture and yellowing. In addition, PI-SiO2 aerogels exhibit the capability to absorb a significant proportion of UV light within the 200–400 nm, offering distinct advantages in transparent thermal insulation materials. The multifunctional PI-SiO2 aerogels can be used as candidate materials in the fields of architecture, automobile, electronics, solar energy and aerospace.

Influence of the synthesis route on optical and luminescence properties of glass-ceramic doped with europium ions

The production of transparent glass-ceramic materials often faces challenges, such as inhomogeneities, inclusions, uncontrolled crystallization and other defects that make glass ceramics unsuitable for fiber optics, for example. At the same time, the chosen chemical composition is valuable for its unique properties. The present study investigated the effect of different methods of synthesizing glass-ceramic silica-germanium-antimony matrices on their transmittance optimization and luminescence properties where the conventional melt-quenching route is insufficient in terms of the transparency and homogeneity of the material obtained. The effect of heat treatment on the studied properties was also considered. Full Text: PDF References G.A. Khater, E.M. Safwat, J. Kang, Y. Yue, A.G.A. Khater, "Some Types of Glass-Ceramic Materials and their Applications", Int. J. Res. Stud. Sci. 7(3), 1 (2020). DirectLink J. Deubener, M. Allix, M.J. Davis, A. Duran, T. Höche, T. Honma, et al., "Updated definition of glass-ceramics", J. Non-Crystalline Solids 501, 3 (2018). CrossRef W. Blanc, Y. Gyu Choi, X. Zhang, M. Nalin, K.A. Richardson, G.C. Righini, et al., "The past, present and future of photonic glasses: A review in homage to the United Nations International Year of glass 2022", Progr. Mat. Sci. 134, 101084 (2023). CrossRef P. Golonko, M. Kochanowicz, P. Miluski, M. Kuwik, J. Pisarska, W. Pisarski, J. Dorosz, M. Leśniak, D. Dorosz, A. Basa, J. Żmojda, "Glass-ceramic optical fibers with controlled crystallization of core doped with europium ions", Ceram. Int. S0272884224002955 (2024). CrossRef J. Zmojda, M. Kochanowicz, P. Miluski, A. Baranowska, A. Basa, R. Jadach, M. Sitarz, D. Dorosz, "The influence of Ag content and annealing time on structural and optical properties of SGS antimony-germanate glass doped with Er3+ ions", J. Mol. Struct. 1160, 428 (2018). CrossRef X. Liu, J. Zhou, S. Zhou, Y. Yue, J. Qiu, "Transparent glass-ceramics functionalized by dispersed crystals", Progr. Mat. Sci. 97, 38 (2018). CrossRef T.N.L. Tran, A. Chiasera, A. Lukowiak, M. Ferrari, "Eu3+ as a Powerful Structural and Spectroscopic Tool for Glass Photonics", Materials 15, 1847 (2022). CrossRef Z. Li, L. Tan, C. Chen, D. Zhou, L.R. Jensen, J. Ren, Y. Zhang, J. Qiu, Y. Yue, "The effect of melt-homogenization and heat-treatment on the optical properties of the rare earth doped oxyfluoride glass-ceramics", J. Non-Cryst. Solids 593, 121773 (2022). CrossRef D. Dorosz, M. Kochanowicz, R. Valiente, A. Diego-Rucabado, F. Rodríguez, N. Siñeriz-Niembro, et al., "Pr3+-doped YPO4 nanocrystal embedded into an optical fiber", Sci Rep. 14, 7404 (2024). CrossRef

In-plane thermal conductivity measurements of Si μ-cantilevers using the suspended thermo-reflectance (STR) technique.

The Suspended Thermoreflectance (STR) technique is described in this paper. This optoelectronic measurement tool performs thermal characterization of freestanding micro-/nanoscale materials. STR performs thermal mapping at the submicron level and produces unconstrained thermal conductivity unlike other optical measurement techniques where independent conductivity measurement is not possible due to their reliance on heat capacity. STR works by changing the temperature of a material and collecting the associated change in light reflection from multiple points on the sample surface. Reflection is a function of the material being tested, the wavelength of the probe light, geometry, and the composition of the specimen for transparent and quasi-transparent materials. In this article, Si μ-cantilevers are studied. In addition, a thermal analytical model is developed and incorporated with optical equations to characterize the conductivity of the Si μ-cantilevers. The analytical model is compared with a finite element model to check its applicability in the STR experiment and data analysis. To validate the technique, the thermal conductivity of 2 and 3 µm thick Si μ-cantilevers was determined using STR at a temperature range of 20-350K and compared to simulations using the equation of phonon radiative transfer and literature values.

Study on the Effect of Focusing Parameters of Ultrashort Pulses on the Process of Laser Welding of Transparent Materials with Metals

Study on the Effect of Focusing Parameters of Ultrashort Pulses on the Process of Laser Welding of Transparent Materials with Metals

A visible transparent infrared microwave compatible stealth metasurface with low infrared emissivity

Abstract This article proposes a visible transparent infrared microwave-compatible stealth metasurface with low infrared emissivity, aiming to integrate visible transparency, low infrared radiation, and broadband microwave absorption. The entire structure consists of a dual layer of infrared shielding layer (IRSL) and microwave absorption layer (MAL). Among them, IRSL adopts a frequency selective surface (FSS) structure with high-duty cycle dielectric-metal-dielectric (DMD) to obtain low infrared emissivity and high microwave transmittance. MAL combines the equivalent circuit method (ECM) and particle swarm optimization algorithm (PSO) to design a circular ring metasurface for broadband microwave absorption. To achieve better absorption performance, a transition layer (TL) is introduced to improve impedance matching between IRSL and MAL. Meanwhile, the use of transparent materials throughout the entire structure has the characteristic of visible transparency. In summary, this article proposes a multiband compatible stealth metasurface design method that can meet the stealth requirements of modern battlefields.

Starch-calcium inclusion complexes: Optimizing transparency, anti-fogging, and fluorescence in thermoplastic starch

With the increasing demand for anti-fogging transparent material and environmental concern, developing sustainable intrinsically hydrophilic and anti-fogging thermoplastic material is important. In this work, thermoplastic starch (TPS) films with good anti-fogging and optical properties were prepared via coordinative interactions with calcium chloride (CaCl2), zinc chloride (ZnCl2) and magnesium chloride (MgCl2). Among them, TPS with the incorporation of CaCl2 exhibited excellent anti-fogging and high optical transparency. Notably, the haze of TPS-0.2Ca just increased from 2.5 % to 3.8 %, with transparency remaining robust at 80 %. FTIR, XPS and 2D-WAXD results demonstrated the formation of inclusion complexes between Ca2+ and hydroxyl groups, which could modulate the hydrophobicity and hydrophilicity of TPS. Moreover, DMA, POM, and AFM results revealed that the formation of starch-calcium inclusion complex was crucial for achieving uniform intensity distribution, reduced crystalline areas, minimized light scattering, and decreased surface roughness, thereby contributing to the high transparency and low haze of TPS-Ca. Furthermore, TPS-Ca samples exhibited inherent fluorescent properties under UV light, showing the potential as disposable and eco-friendly fluorescence materials. This work provides new insights into design of sustainable TPS-based materials that combine robust antifogging performance with advanced optical property.

Biomimetic Transparent Slippery Surface for the Locomotion of Photocontrol Droplets and Bubbles.

Directed transportation and collection of liquids and bubbles play a vital role in the survival of ecosystems. Among them, the optical response control is widely used in the fields of microfluidic chips and chemical synthesis because of its high remote operation and fast response speed. However, due to poor light transmission, the development direction of traditional near-infrared (NIR) absorbing materials in the field of visualization is limited, and there are few reports of manufacturing an operating platform that can realize the directional movement of droplets/bubbles on a single platform. Here, a transparent photo-responsive PBFS platform is prepared for droplet and bubble manipulation by coating the etched glass substrate with Prussian blue (PB) nanocubes. When near-infrared (NIR) irradiation on the PBFS platform, PB nanocubes trigger heat production by photothermal means, due to the action of Marangoni force, the surface tension on the left and right sides of the droplets and bubbles is not uniform, forming a surface tension gradient, thereby driving the movement of the droplets and bubbles. The control platform has good application potential in the field of microchemical reaction and biomedical engineering and brings new solutions to the field of transparent photothermal materials.

On tailored microstructure in AA 2024 alloy during in-situ microwave casting

In the present study, application of microwave energy was explored for tailoring the microstructure in AA 2024 alloy through directional solidification route. Microwave transparent (alumina) and absorbing (graphite) mould materials were utilized to investigate the effect of microwave interaction (electric and magnetic field components) with AA 2024 alloy on microstructure evolution in terms of dendrite size distribution and formation of eutectic phase. Results showed more pronounced eutectic phase gradient was developed using alumina mould. On the other hand, a more uniform distribution of the eutectic phase and grain size was observed with graphite mould. The development of the eutectic phase gradient is attributed to the effective microwave interaction with the AA 2024 alloy melt during solidification. This is primarily associated with the formation of an additional flux at the solid-liquid (S/L) interface of the alloy under the effect of magnetic field and an enhancement in diffusion flux due to mass transport caused by electric field component of microwave. Formation of AlCu, Al2Cu, and Al2CuMg intermetallic phases in both alumina and graphite mould casts was confirmed. Significantly higher hardness was observed at the higher eutectic phase sites within the alumina mould cast, whereas graphite mould casts exhibited better tensile properties.

Transparent, Antibiofouling Window Obtained with Surface Nanostructuring.

Biofouling is one of the key factors which limits the long-term performance of seawater sensors. Common measures to hinder biofouling include toxic paints, mechanical cleaning and UV radiation. All of these measures have various limitations. A very attractive solution would be to prevent biofilm formation by changing the surface structure of the sensor. This idea has been implemented successfully in various settings, but little work has been done on structuring optically transparent materials, which are often needed in sensor applications. In order to achieve good antibiofouling properties and efficient optical transparency, the structuring must be on the nanoscale. Here, we investigate a transparent, antibiofouling surface obtained by patterning a semihexagonal nanohole structure on borosilicate glass. The nanoholes are approximately 50 nm in diameter and 200 nm deep, and the interparticle distance is 135 nm, allowing the structure to be optically transparent. The antibiofouling properties of the surface were tested by exposing the substrates to the microalgae Phaeodactylum tricornutum for four different time intervals. This species was chosen because it is common in the Norwegian coastal waters. The tests were compared with unstructured borosilicate glass substrates. The experiments show that the nanostructured surface exhibits excellent antibiofouling properties. We attribute this effect to the relative size between the structure and the biofouling microorganism. Specifically, the small dimensions of the nanoholes, compared to the biofouling microorganism, make it more difficult for the microalgae to attach. However, lubrication of the substrates with FC-70 perfluorocarbon resulted in contamination at a rate comparable to the reference substrate, possibly due to the chemical attractiveness of the alkane chains in FC-70 for the microalgae.

Topography prediction at boundaries between sub-regions in the 5-axis milling of Plexiglas based on dimension reduction method

Sub-regional milling has become an important machining method in the production of free-form surface parts. However, due to complex tool paths, irregular surface topography can occur at the region boundaries, which in turn affects the performance of the part such as the light transmission, optical distortion and mechanical strength of non-metallic transparent material etc. It is vital for manufacturers and researchers to study the forming mechanism of topography at boundaries and then to control it to get the high quality of the machined surface. Therefore, this paper thoroughly investigates the formation of surface topography at the boundary of sub-regions in the five-axis machining process. First, the boundaries of sub-regions are classified. Simultaneously, swept surfaces of the cutting edge, taking into account the process parameters and tool path, are constructed. Then, the surface topography is calculated using an improved model based on dimension reduction theory. Furthermore, through simulation and experiments, the predicted surface topographies agree well with the measured ones. Finally, some conclusions are listed and the method in this paper can provide a reliable basis for manufacturing high-quality parts.

Elucidating the origin of laser induced nonlinearities in propagation inside transparent medias: A comparative numerical study of silicon and fused silica

Abstract The creation of localized bulk modification using femtosecond pulses inside semiconductors like silicon (Si) is quite challenging whereas it is not difficult to achieve it for dielectric material like fused silica (FS). So, this report addresses the fundamental origin of this issue. By taking simple numerical approach, it has been found that in FS we can deliver stronger fluence due to self-focusing on higher power level as compared to Si. The origin for the above lies on the spatial-temporal pulse-splitting behavior which is dominant in case of FS at the focus, whereas for Si it is only effective after focus. We have also considered the influence of plasma and Kerr terms to elucidate the reason behind such nonlinearities. For FS case, omission of Kerr term dominates whereas for Si the influence of each term does not significantly create self-focusing like FS under a similar focusing condition. This study could make an important guideline for researchers to understand the complexity of laser-matter interaction in transparent materials specifically being studied by many laser processing industries.