Porous Glass Research Articles

Coexistence of Superconductivity and Magnetic Ordering in the In–Ag Alloy Under Nanoconfinement

The impact of the interface phenomena on the properties of nanostructured materials is the focus of modern physics. We studied the magnetic properties of the nanostructured In–Ag alloy confined within a porous glass. The alloy composition was close to the eutectic point in the indium-rich range of the phase diagram. Temperature dependences of DC magnetization evidenced two superconducting transitions at 4.05 and 3.38 K. The magnetization isotherms demonstrated the superposition of two hysteresis loops with low and high critical fields below the second transition, a single hysteresis between the transitions and ferromagnetism with weak remanence in the normal state of the alloy. The shape of the loop seen below the second transition, which closes at a low magnetic field, corresponded to the intermediate state of the type-I superconductor. It was ascribed to strongly linked indium segregates. The loop observed below the first transition is referred to as type-II superconductivity. The secondary and tertiary magnetization branches measured at decreasing and increasing fields were shifted relative to each other, revealing the proximity of superconducting and ferromagnetic phases at the nanometer scale. This phenomenon was observed for the first time in the alloy, whose components were not magnetic in bulk. The sign of the shift shows the dominant role of the stray fields of ferromagnetic regions. Ferromagnetism was suggested to emerge at the interface between the In and AgIn2 segregates.

Chiral Electrokinetic Phenomena in Single Nanopores

AbstractThe arrangement of solvent molecules and ions at solid–liquid interfaces determines electrochemical properties that are important in separations platforms, sensing technologies, and energy‐storage systems. Here we show that single glass and polymer pores in contact with propylene carbonate (PC) solutions of LiClO4 exhibit an effective surface potential that is modulated by the enantiomeric excess of the solvent. In particular, electrochemical and electrokinetic measurements of ionic transport through glass pipettes and polymer pores reveal that the effective surface potential is significantly lower in solutions prepared using enantiomerically pure PC than in solutions prepared using racemic PC. Both pore systems became positively charged in all racemic solutions examined in the range of LiClO4 concentrations between 1 mM and 100 mM, whereas solutions in (R)‐(+)‐PC induced a positive surface potential only at concentrations above ~5 mM. The effective surface potential is quantified through asymmetry in current–voltage curves and zeta‐potential measurements. Vibrational sum‐frequency‐generation experiments on LiClO4 solutions in racemic and enantiomerically pure PC indicate that the surface lipid‐bilayer‐like region in the former is more strongly organized than in the latter, dictating the favorable positions for lithium and perchlorate ions in each case. The more ordered molecular packing in the racemic liquid leads to accumulation of lithium ions on the outside of the bilayer, creating a higher effective positive charge. Our results highlight the extreme sensitivity of the interfacial potential on molecular organization of the solvent, and the relatively unexplored role that chirality can play in electrokinetic phenomena.

Borosilicate glass with low dielectric loss and low permittivity for 5G/6G electronic packaging applications

A phase-separated borosilicate glass, with a relative permittivity ranging from 3 to 3.5 and a loss tangent as low as 5.6 × 10−4, is presented for packaging applications for the next generation of mobile communications. Ionic polarizability for each borosilicate composition was calculated from the Clausius–Mossotti relationship for both the vitreous and crystalline structures, and the polarizability difference between the two is proportional to the dielectric loss. Small amounts of alkali modifier were added to improve the glass processability, and the loss tangent increased to the 1–7 × 10−3 range. The resulting glass is phase-separated, which has no impact in the millimeter-wave spectrum, as the wavelengths are considerably greater than the length scale of each immiscible phase.

Sunflower-disc-inspired vertical growth of 2D ZnIn2S4 on ultra-thin TiO2: Constructing a 3D porous photocatalytic glass film for ultra-efficient organic pollutant degradation

Thin-film catalysts show immense potential for photocatalytic applications due to their versatility and ease of recovery. However, their stability is often compromised by detachment and poor surface utilization. In this study, inspired by the architecture of sunflower discs, we present a novel 3D porous photocatalytic film by vertical growth of 2D ZnIn2S4 on ultra-thin TiO2/glass for ultra-efficient degradation of organic pollutants. Crucially, ZnIn2S4 nanosheets were vertically grown on the stable TiO2/glass substrate to form a 3D porous structure, and the vertical growth mechanism is demonstrated by DFT. In contrast, when directly grown on glass, only aggregated ZnIn2S4 spheres formed. The enhanced surface area of the 3D ZnIn2S4 structure allows for maximum light absorption, while the rapid separation and transfer of photogenerated charges follow a Z-scheme charge transfer mechanism in the ZnIn2S4/TiO2 heterojunction. This synergy significantly improves the photocatalytic performance, surpassing most previously reported semiconducting films.

Extraction of nickel ions using nanoporous adsorbent material from waste glass

This study aims to create a porous glass adsorbent from waste glass to extraction nickel ions from its aqueous solution. The process involves converting waste glass to porous glass using 1:1:1:1 lime, sodium chloride, and sodium bicarbonate, followed by reacting with waste glass at 800 ˚C. The porous glass surface morphology, elemental composition, and functional groups, were analyzed using SEM, EDS, and FT-IR techniques.The outcome parameters used in this study are adsorbent dosage (10 g), contact time (150 min), heavy metal ion concentration (100 mg/l), and pH of 6. The adsorption capacity resulting from these parameters is 9.28 mg/g using the porous extract adsorbent for the extraction of nickel ions from its solutions. According to the findings. The proportion of Ni (II) ions extracted increased, coupled with a rise in the adsorbent dosage, heavy metal ion concentration, contact time, and pH. In addition, the Langmuir isotherm (R2 = 0.98,KL=0.072) has shown better performance than the Freundlich adsorption isotherm (R2 = 0.93,N=1.598) for the adsorption of the Ni(II) in this study.

Effect of restricted geometry on phase transitions in nanostructured sodium nitrate

The study of structure of nanocomposite material based on porous glass with 7 nm average pore diameter filled by sodium nitrate from the melt under pressure has been carried out by synchrotron radiation diffraction upon heating and cooling. The temperature evolution of the elastic peak lineshapes corresponding to the sodium nitrate structure has been analyzed, and it is shown, that in the “virgin” sample there are two types of nanoparticles with dendrite spatial organization and with fundamentally different characteristic sizes. The temperature dependences of the critical index β(T) for the structural transition in sodium nitrate have been obtained, and the crossover in this dependence for nanoparticles with a characteristic size of about 20 nm has been found at T∗ ∼ 445 K both upon heating and cooling. The temperatures of the structure and “melting – crystallization” phase transitions observed in this nanocomposite have been determined.

Development and Application of an Advanced Percolation Model for Pore Network Characterization by Physical Adsorption.

Physical adsorption is one of the most widely used techniques to characterize porous materials because it is reliable and able to assess micro- and mesopores within one approach. Challenges and open questions persist in characterizing disordered and hierarchically structured porous materials. This study introduces a pore network model aimed at enhancing the textural characterization of nanoporous materials. The model, based on percolation theory on a finite-sized Bethe lattice, includes all mechanisms known to contribute to adsorption hysteresis in mesoporous pore networks. The model accounts for delayed and initiated condensation during adsorption as well as equilibrium evaporation, pore blocking, and cavitation during desorption. Coupled with dedicated nonlocal-density functional theory kernels, the proposed method provides a unified framework for modeling the entire experimental adsorption-desorption isotherm, including desorption hysteresis scans. The applicability of the method is demonstrated on a selected set of nanoporous silica materials exhibiting distinct types of hysteresis loops (types H1, H2a, H1/H2a, and H5), including ordered mesoporous silica networks (KIT-6 and SBA-15/MCM-41 hybrid silica with plugged pores) and disordered mesoporous silica networks (hierarchical meso-macroporous monolith and porous Vycor glass). For all materials, a good correlation is found between calculated and experimental primary isotherms as well as desorption scans. The model allows us to determine key pore network characteristics such as pore connectivity and pore size distributions as well as a parameter correlated with the impact of pore network disorder on the adsorption behavior. The versatility and enriched textural insights provided by the proposed novel network model allow for a comprehensive characterization previously inaccessible and hence will contribute to further advancement in the textural characterization of novel nanoporous materials. It has the potential to provide important guidance for the design and selection of porous materials for optimizing various applications, including separation processes such as chromatography, heterogeneous catalysis and gas and energy storage.

Process Mapping of the Sol-Gel Transition in Acid-Initiated Sodium Silicate Solutions.

Fabricating large-scale porous bioactive glass bone scaffolds presents significant challenges. This study aims to develop formable, in situ setting scaffolds with a practical gelation time of about 10 min by mixing 45S5 bioactive glass with sodium silicate (waterglass) and an acid initiator. The effects of pH (2-11), waterglass concentration (15-50 wt.%), and acid initiator type (phosphoric or boric acid) were examined to optimize gelation kinetics and microstructure. A 10 min gelation time was achieved with boric acid and phosphoric acid at various pH levels by adjusting the waterglass concentration. Exponential and polynomial models were proposed to predict gelation times in basic and acidic environments, respectively. The optical properties of the gels were studied qualitatively and quantitatively, providing insights into gelation kinetics and structure. Acidic gels formed smaller particles in a dense network (pores < 550 nm) with higher light transmittance, while basic gels had larger aggregates (pores ~5 µm) and lower transmittance. As the waterglass concentration decreased, pore size and transmittance converged in both groups. The onset of gelation was detected around 8 min using the derivative of light transmittance. This work identifies the key factors controlling waterglass gelation and their impact on gel structure, enabling the tailored creation of formable, in situ setting bioactive glass bone scaffolds.

Fabrication of Spherical Colloidal Supraparticles via Membrane Emulsification.

Colloidal supraparticles are micrometer-scale assemblies of primary particles. These supraparticles have potential application in photonic materials, catalysis, gas adsorption, and drug delivery. Thus, the synthesis of colloidal supraparticles with a narrow size distribution and high yield has become essential. Here, we demonstrate membrane emulsification as a high-throughput approach for fabricating spherical supraparticles with a narrow size distribution and control over particle size and crystallinity. Spherical supraparticles with well-ordered surface structures are synthesized by generating emulsion droplets of an aqueous colloidal dispersion in fluorocarbon oil using a Shirasu porous glass membrane followed by the consolidation of particles through water removal within the emulsion. We systematically investigate process parameters, including the flow rate of the particle dispersion, the particle concentration, and the average pore diameter of the membrane, on the mean size and size distribution of the supraparticles, revealing key factors governing supraparticle properties and production throughput. A comparative evaluation with commonly employed methods highlights the advantage of membrane emulsification, which combines well-defined internal structure and controlled supraparticle sizes with comparably high yields on the order of tens of grams per day. Importantly, in contrast to widely used droplet-based microfluidics, membrane emulsification allows fabrication of supraparticles in nonfluorinated oil. Overall, membrane emulsification offers a simple yet versatile method for fabricating colloidal supraparticles with high quality and yield and may serve as a bridge between existing high-precision techniques, such as droplet-based microfluidics, and high-throughput processes with less control, such as spray-drying.

Inherent porosity of Zeolitic Imidazolate Framework-62 melt leading to formation of the porous melt-quenched glass

Porous glasses produced through melt-quenching of some selective metal organic frameworks like Zeolitic Imidazolate Framework-62 (ZIF-62) and ZIF-4 belong to the advanced functional materials because of their inherent porosity, ease of processing, high gas adsorption capacity and gas separation selectivity. We have delineated thermal induced modifications in the porosity features (pore size, size-distribution and pore density) of crystalline ZIF-62 from room temperature (RT) to its melt-state (> melting point, Tm) followed by its quenching, back to RT, carrying out the depth sensitive positron annihilation lifetime spectroscopy (PALS) measurements in-situ at varying temperatures (RT−Tm). On heating under vacuum, the pores' size as well as size-distribution of crystalline ZIF-62 increases up to ∼473 K as a consequence of removal of entrapped solvent molecules and nonuniform thermal expansion. At higher temperatures (∼473 −573 K), a reduction in pores’ size and size-distribution is observed due to the loss of long range ordering and volume collapse. On melting, ZIF-62 turns into a porous liquid having ∼1.4 times larger pores compared to its crystalline form. The quenching of this porous melt is fully irreversible, and results in the formation of a porous glass having the pores larger than its crystalline counterpart. The in-situ PALS investigation provides the first experimental evidence of inherent porosity in ZIF-62 melt existing at high temperature that has been predicted before through molecular dynamics simulation of the ZIFs-based melts.

Sound-absorbing properties of porous glass ceramics from zeolite-containing rocks

Sound-absorbing properties of porous glass ceramics from zeolite-containing rocks

Intermittent in-situ high-resolution X-ray microscopy of 400-nm porous glass under uniaxial compression: Study of pore changes and crack formation

Understanding the relationship between the structure of porous glasses and their failure behavior is crucial for developing reliable porous glasses for specific applications. In this study, we used nanometer resolution X-ray computed tomography (nano-CT) to image a controlled pore glass (CPG) with 400 nm-sized pores under in-situ uniaxial compression. Our results demonstrate that in-situ nano-CT is an excellent tool for identifying damage mechanisms in 400 nm pore glass. It allowed us to track changes in the shape of pores and pore walls during compression until the specimen failed. We also used computational tools to analyze the microstructural changes within the CPG sample, mapping displacements and strain fields. Additionally, we simulated the behavior of the CPG using a Fast Fourier Transform/Phase Field method. Both experimental and numerical data revealed local shear deformation occurring along bands, consistent with the appearance and propagation of ± 45-degree cracks.

Multicompartment microparticles of SBM triblock terpolymers: Morphological transitions through homopolymer blending

AbstractBlock copolymers (BCPs) have recently been explored in spherical confinement to form internally structured microparticles. While the behavior of AB diblock copolymers in confinement is comparably well studied, knowledge on confined ABC triblock terpolymers is still rather sparse. The latter are especially interesting as the third block allows the formation of a broader variety of multicompartment microparticles (MMs), but their synthesis is often realized through sequential polymerization, which can be work intensive and challenging. Here, we demonstrate that blending linear ABC triblock terpolymers with homopolymers is a versatile and straightforward method to tune the microphase behavior in MMs. We systematically blend polystyrene-block-polybutadiene-block-poly(methyl methacrylate) (SBM or PS-b-PB-b-PM) with homopolymers of hPS, hPB, or hPM, to study the feasibility of this approach to replicate specific morphologies or access new ones. We utilize Shirasu Porous Glass (SPG) membrane emulsification and evaporation-induced confinement assembly (EICA) to produce narrowly size-dispersed MMs with defined inner structure. We analyze the MMs with dynamic light scattering (DLS), as well as transmission and scanning electron microscopy (TEM, SEM). We show that the resulting blend morphologies can be identical to those of the unblended SBM at same composition and that, depending on the location in the ternary microphase diagram, one SBM morphology can be converted into multiple different morphologies. Graphical Abstract

Rapid phenol mineralisation in a low-pressure dead-end light transmitting photocatalytic membrane reactor (LT-PMR)

Photocatalytic membrane reactors (PMRs) are widely studied for wastewater decontamination but reactions are too slow for scaled up application. This PMR study proposes a novel operation involving rapid decontamination in just one pass through the confined space within the membrane. This approach was demonstrated for the first time by light transmitting PMR (LT-PMR), conveniently receiving UV LED light (λpeak = 365 nm) via the permeate side to the photocatalyst P25 TiO2 microfiltration membrane coated on porous glass. A 93 % reduction in model contaminant phenol concentration from a 10 mg/L feed occurred at a flux of 4.7 L/m2/h. The phenol degradation occurred without any additional residence time from external vessels or recirculation. Phenol was almost entirely mineralised, confirmed by total organic carbon (TOC) measurements, with trace by-products identified by high pressure liquid chromatography (HPLC) analysis. Mass transfer and reaction rate constants from Langmuir-Hinshelwood modelling were comparable to literature. Highest reaction rates occurred at lowest permeate phenol concentrations, highlighting potential to destroy recalcitrant pollutants persisting through established treatments. LT-PMR is therefore an effective and practical process that very rapidly destroys phenol. Further work to explore improved flux by enhanced light transmission, tailored catalytic materials and demonstration on other pollutants and water matrices is warranted.

Micro-PIV of viscoelastic fluid flow in microporous media

The present experimental investigation combines the bulk flow properties of polymer solutions and measurable rheological parameters as they flow through a distinctive micro-porous structure, with micro-PIV (micro-particle image velocimetry) to measure the velocity distribution and velocity fluctuations within individual pores of a novel porous glass structure. To investigate the effects of fluid elasticity at pore scale, aqueous solutions of a polyacrylamide (PAA) & polyethylene oxide (PEO) in the concentration range of 50–200 ppm, which were characterized in both shear and extensional flows using shear and capillary break-up extensional rheometers (CaBER) respectively, were used as working fluids. The velocity field measurement includes the velocity magnitude and fluctuation intensity in several different pores within the porous material across a Weissenberg number Wi range of approximately 0.01 to 1 for each of the test fluids. The global averaged fluctuation intensity increases with Wi but the critical value, which indicates the onset of significant unsteadiness (i.e. well above noise floor/Newtonian baseline) within the flow at pore scale gives an approximately constant value of Wi≈0.4, which is almost 40 times higher than the value that is observed in the pressure-drop measurements for the data to rise above the Newtonian base line. We therefore postulate that the enhanced pressure-drop behaviour of the bulk flow may not be due to local velocity fluctuations within the pores but due to mean flow effects, at least over a significant portion of the data (up to Wi≈0.4).

Multiple layers, porous surface, and their role in increasing the efficiency of photocatalytic coating on (DD3, DD3+ZrO2) ceramics and glass

Magnesium-doped zinc oxide thin films were dip-coated onto porous ceramic and glass substrates under identical conditions (50 layers, same doping ratio). Structural, morphological, and photocatalytic properties were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), UV–visible spectrophotometry, and confocal microscopy. XRD analysis indicated a shift in peak positions towards higher angles, increased grain size, and lattice distortion on both substrates. Unique flower-shaped crystalline granulates were observed exclusively on the ceramic substrate (DD3Z). The energy gap decreased on the ceramic and increased on the glass substrate. The photocatalytic activity was evaluated using an aqueous orange II solution, showing significantly higher decomposition (80 ± 0.53 % after 6 h) on the ceramic compared to the glass substrate (30 %). The enhanced performance on ceramic substrates, particularly with DD3+ZrO2, was attributed to increased microporosity, surface roughness, and active material incorporation, facilitating greater photocatalytic efficiency. The findings suggest promising applications of these materials for efficient and cost-effective photocatalysis, with potential for reuse after thermal treatment at 500 °C.

A high-performance digital polymerase chain reaction chip integrated with nanorods-decorated microchannel plate

Abstract In this paper, we report on a digital PCR chip integrated with microchannel plate (MCP) for the quantification of DNA molecules. MCP, a highly porous glass membrane, is employed here as microreactors. The density of the microreactors reaches up to 1600 mm−2 with a total number of 40,000 chambers each in 100 pL volumes embedded in a 5 × 5 mm2 MCP, which is 100 times larger than that of the conventional microfabricated chips. In addition, the MCP is functionalized with ZnO nanorods to enhance the fluorescence signal. The dynamic range is noted as 105 and the detection limit of λDNA is determined to be 1.4 copies/μL.

Synthesis of Bulk-Nucleated Glass–Ceramics and Porous Glass–Ceramic Composites through Utilization of Fly Ashes

Synthesis of Bulk-Nucleated Glass–Ceramics and Porous Glass–Ceramic Composites through Utilization of Fly Ashes

A sol-gel templating route for the synthesis of hierarchical porous calcium phosphate glasses containing zinc

Hierarchical porous phosphate-based glasses (PPG) have great potential in biomedicine. Micropores (pore size <2 nm) increase the surface area, mesopores (pore size 2–50 nm) facilitate the absorption and diffusion of therapeutic ions and molecules making them ideal controlled delivery systems, while macropores (pore size >50 nm) facilitate the movement and diffusion of cells and fluids. In addition, the bioresorbability of PPG allows for their complete solubility in body fluid, alongside simultaneous formation of new tissue. Making PPG via the traditional melt-quenching (MQ) synthesis method used for phosphate-based glasses (PG), is not straightforward. Hence, we present here a route for preparing such glasses using a combination of sol-gel (SG) and templating methods. Hierarchical PPG in the P2O5–CaO–Na2O system with the addition of 1, 3 and 5 mol % of Zn2+ were prepared with pore dimensions ranging from the micro-to the macro scales using Pluronic 123 (P123) as a surfactant. The presence of micropores (0.30–0.46 nm), mesopores (1.75–9.35nm) and macropores (163–207 nm) was assessed via synchrotron-based Small-Angle X-ray Scattering (SAXS), with the presence of the latter two confirmed by Scanning Electron Microscopy (SEM). Structural characterisation performed using 31P solid state magic angle spinning nuclear magnetic resonance (MAS NMR) and Fourier Transform Infrared (FTIR) spectroscopies shows the presence of Q2, Q1 and Q0 phosphate species with a predominance of Q1 species in all compositions. Dissolution studies in deionised (DI) water confirm that controlled release of phosphates, Ca2+, Na+ and Zn2+ is achieved over a period of 7 days. In particular, the release of Zn2+ is proportional to its loading, making its delivery particularly easy to control.

Controllable growth of Ce3+-doped fluoride nanocrystals (LaF3/KLaF4) in fluorosilicate glass

Controllable growth of nanocrystals (NCs) in optical glasses is essential to impart photonic functions for demanded applications. Here, Ce3+-doped KLaF4 and LaF3 fluoride NCs are controllably precipitated in a fluorosilicate glass via adjusting the duration and temperature of thermal treatment. The presence of phase separation in the precursor glass (PG) is derived from molecular dynamics (MD) simulations, and serves as the driving factor for the crystallization of fluoride NCs. The phase separation of PG, NCs distribution, microscopic morphology and particle size of NCs precipitated in the nano-glass composites (nano-GCs) are investigated by analytical transmission electron microscopy (TEM). Structural and spectroscopic characterizations confirm the influence of the thermal treatment on the crystalline species in the nano-GCs. The developed nano-GCs exhibit intense X-ray excited luminescence with an excellent linearity with the X-ray dosage and a good thermal stability, making them suitable for radiation detection and medical imaging applications.