Porous Glass Materials Research Articles

Monodisperse Porous Emitter Materials for Ion Electrospray Propulsion

Electrospray spacecraft propulsion typically uses commercially available porous glass materials for their emitter components. The quality of this emitter material is crucial to the operation of the thrusters, as nonuniformities in the pore distribution can lead to differential propellant flow rates, variation in tip geometries, and less-than-optimal performance of the thruster. The focus of this work is on the development of new porous materials that are more uniform and can mitigate these issues caused by nonuniformities present in current commercially available porous materials. A silica nanoparticle photo-curable resin solution is developed to create high-uniformity porous substrates to improve tip geometry and overall thruster performance.

Spectral Properties of Nanostructured Composite Glass Materials Activated by Yttrium in the Presence of Copper or Bismuth

Composite materials (CMs) based on porous glass matrices activated by yttrium in the presence of copper or bismuth are synthesized. It is established that, depending on the composition, the CM samples exhibit UV, blue-green, red, and infrared luminescence due to the presence of various centers, including Bi3+ and Cu+ ions, F centers in Y2O3, and molecular ions О3–2 associated with cation vacancies Y3+.

Physicochemical Substantiation of Obtaining Porous Glass Materials from Silica-Containing Raw Materials

Physicochemical Substantiation of Obtaining Porous Glass Materials from Silica-Containing Raw Materials

Synthesis of bioactive glass using cellulose nano fibre template

This study introduces a templating approach using a cellulosic suspension to create a porous SiO2–CaO–P2O5–Na2O bioactive glass material. Sol-gel approach was used as the synthesis method. Carbon nanofibers in suspension form was used as the templating material. The amount of CNF used in the experiment ranged from 5% to 25% by volume. The morphology, porosity, crystallinity of the combeite phase, mechanical and chemical properties of the BG samples were examined. The findings show that the templating method had no effect on the formation of the required functional elements, such as Si, Ca, Na and P. The porosity of the BG materials improves by 15% after templating compared to the neat sample. The formed pores were assumed to be homogenous based on the uniform adsorption and desorption BET profiles. The crystallization mechanisms during the sintering process were affected by the templating approach, indicating the need for a specific amount of template to be used in the preparation step. Both the sintering temperatures and the CNF content affected the formation of the combeite phase. The BG samples had excellent mechanical properties and are suitable for use in cancellous bone applications. As a result, this study shows a novel method for synthesizing porous bioactive glass materials via the sol-gel method and a CNF suspension as a template.

Effect of pore size on phase transitions in rubidium tetrachlorozincate nanoparticles in porous glass matrices

Effect of pore size on phase transitions in rubidium tetrachlorozincate nanoparticles in porous glass matrices

Influence of the Heat Treatment Conditions on the Elemental Composition and Spectral Properties of Composite Materials Based on Silicate Porous Glass Doped by AgI and Er3+ Ions

Composite materials (CMs) doped by AgI and Er3+ ions are synthesized based on high-silica porous glass matrices. The structures of the CMs are investigated by IR spectroscopy in the frequency range 1100–400 cm–1. The IR transmission spectra of the CMs exhibit bands corresponding to vibrations of the Ag–O, Ag–O–Ag, Er–O–H, and Er–O bonds. In addition, bands that are caused by the presence of Ag2O, AgI, and Er2O3 are found. Energy-dispersive X-ray spectroscopy shows that the conditions of treatment of CMs with heat have an effect on the concentration distribution of elements over the thickness of the samples.

Thermochemical Conversion of Waste Glass and Mollusk Shells into an Absorbent Material for Separation of Direct Blue 15 Azo Dye from Industrial Wastewater.

The objective of the presented work was to convert waste glass and mollusk shells into a porous material for separation of the direct blue 15 azo dye from industrial wastewater. The porous glass material of specific pore size and surface area was prepared through a thermochemical reaction by reacting waste glass with mollusk shells, soda, and rock salt. The optimal reaction conditions were determined by adjusting the reaction time, reaction temperature, and relative amount of the reactants. The surface morphology, elemental composition, and functional groups of the material were studied through scanning electron microscopy (SEM), X-ray florescence spectroscopy (XRF), energy-dispersive X-ray spectroscopy (EDX), and Fourier transform infrared spectroscopy (FT-IR). Barrett–Joyner–Halenda (BJH) and Brunauer–Emmett–Teller (BET) methods were used to determine the pore size distribution and surface area of the porous material. The material consisted of different types of flakes, oval-shaped particles, and granules. In addition to the functionalized char, the porous material contained Si–O–Si, Si–O–Al, and Si–OH groups. Relatively better yield and pore size distribution were obtained at a reaction temperature of 800 °C and reaction time of 90 min. The fully characterized material was used to separate the blue dye from industrial wastewater. This porous material absorbed about 2.66 mg/g blue dye from wastewater after 20 min of treatment time. The adsorption data fit the Freundlich isotherm better than the Langmuir isotherm. The correlation coefficient of Freundlich isotherm varied from 0.93 to 0.98, which was slightly higher than the correlation coefficient of Langmuir isotherm.

Effects of porous material on transient natural convection heat transfer of nano-fluids inside a triangular chamber

This study numerically investigates the impact of porous materials, nano-particle types, and their concentrations on transient natural convection heat transfer of nano-fluid inside a porous chamber with a triangular section. The governing equations of the two-phase mixture model are separated on the computational domain and solved using the Finite Volume Method, taking into account the Darcy–Brinkman model for porous medium. It was observed that convection heat transfer inside the triangular chamber consists of three stages named initial, transient, and semi-steady. The features of each step are provided in detail. The results suggested that the use of a hybrid nano-fluid (water/aluminum oxide-cooper) inside a porous glass material and an increase in volume fraction of nano-particles have adverse effects on heat transfer rate. In contrast, as the nano-particle volume fraction of the single nano-fluid (water/aluminum oxide) inside the chamber increased, convection heat transfer rate improved. At the same time, it was observed that the use of both nano-fluids (single and hybrid) in the porous environment of the aluminum foam could improve convection.

“Restricted Geometry” Effect on Phase Transitions in KDP, ADP, and CDP Nanocrystals

The dielectric properties of composite materials prepared by the embedding of ferroelectrics potassium dihydrogen phosphate (KDP), cesium dihydrophosphate (CDP), as well as antiferroelectric ammonium dihydrogen phosphate (ADP) into porous glass matrices with an average size of through pores of 7, 46, and 320 nm have been studied. It was found that an increase occurred in the phase transitions temperature (TC) for embedded particles in comparison with corresponding bulk materials. Some possible mechanisms of influence of “restricted geometry” on the Curie temperature are discussed. Estimates of TC shifting as a result of the “pressure effect” caused by elastic stresses in embedded particles as well as the result of bias electric field influence arising due to the piezoelectric effect are made. The possibility of using the tunneling Ising model to explain the experimental results is discussed.

Metal-organic framework glasses with permanent accessible porosity

To date, only several microporous, and even fewer nanoporous, glasses have been produced, always via post synthesis acid treatment of phase separated dense materials, e.g. Vycor glass. In contrast, high internal surface areas are readily achieved in crystalline materials, such as metal-organic frameworks (MOFs). It has recently been discovered that a new family of melt quenched glasses can be produced from MOFs, though they have thus far lacked the accessible and intrinsic porosity of their crystalline precursors. Here, we report the first glasses that are permanently and reversibly porous toward incoming gases, without post-synthetic treatment. We characterize the structure of these glasses using a range of experimental techniques, and demonstrate pores in the range of 4 – 8 Å. The discovery of MOF glasses with permanent accessible porosity reveals a new category of porous glass materials that are elevated beyond conventional inorganic and organic porous glasses by their diversity and tunability.

Properties of Bismuth-Containing High-Silica Glass Depending on the Bismuth Concentration and Heat Treatment. I. Spectral-Optical Properties

Bismuth-containing high-silica glass is synthesized by impregnating porous glass matrices in 0.01–0.5 M aqueous solutions of bismuth nitrate with the subsequent heat treatment at a temperature of 50–875°C. The dependences of the spectral-optical properties of the synthesized glass on the concentration of the doped bismuth (0.02–1.17 wt % Bi2O3) and heat treatment temperature are studied. It is found using the method of optical spectroscopy that bismuth is present in glass in different oxidation states—Bi3+, Bi2+, and $$\rm{Bi_5^{3+}}$$ clusters. Near infrared spectroscopy in the 7500–4000 cm–1 frequency range reveals that an increase in the temperature results in a gradual decrease in the intensity of the absorption bands due to the vibration of hydroxyl groups and water molecules adsorbed on the surface. The glasses (T ~ 50 and 400°C) exhibit bands at 4445–4443, 4433, and 4417–4415 cm–1, which correspond to the absorption of Bi+ ions.

Polymorphism of Ga-In alloys in nanoconfinement conditions

The results of acoustic investigations of the melting and crystallization of indium-gallium alloys of different compositions embedded in porous glass matrices with a pore size of 18 nm are presented. It was shown that the formation of the α and β crystalline modifications of gallium is possible depending on the alloy composition in nanopores. The fraction of β-Ga increased as the indium concentration in the alloy increased. Stabilization of β-Ga in conditions of confined geometry was revealed. Broadening of the melting region of the α phase of gallium and narrowing of the melting region of β-Ga, as compared with the corresponding bulk alloys, were observed.

Formation of filament structures of noble-metal nanoparticles in transparent dielectrics under the action of continuous laser radiation

The formation of filamentary structures (up to 5 mm in length and 5–90 mm thick) of gold and silver nanoparticles (NPs) was studied in porous Vycor glass and polymer material (crosslinked oligouretanmetakrilate) doped with appropriate organic and inorganic precursors of these metals (H[AuCl4] · 4H2O, AgNO3, Ag(hfac)COD) under the action of continuous laser radiation in the visible wavelength range of 5–100 mW power. The formation of such structures along the direction of a laser beam was observed both in the course of laser exposure and after it ended. The mechanism of self-assembling of filaments from metal NPs is rationalized by the photolysis of precursor molecules in the zone of irradiation, the release of metal atoms, and their assembly into NPs. The very process of particle assembly in the filaments are ordered by the effects of self-focusing of laser radiation on a micro lens arising in the matter and channeling it into a medium with a varying refractive index. The features of formation of filamentary structures in the matrices under laser irradiation with different wavelengths are discussed.

Examining porous bio-active glass as a potential osteo-odonto-keratoprosthetic skirt material

Bio-active glass has been developed for use as a bone substitute with strong osteo-inductive capacity and the ability to form strong bonds with soft and hard tissue. The ability of this material to enhance tissue in-growth suggests its potential use as a substitute for the dental laminate of an osteo-odonto-keratoprosthesis. A preliminary in vitro investigation of porous bio-active glass as an OOKP skirt material was carried out. Porous glass structures were manufactured from bio-active glasses 1-98 and 28-04 containing varying oxide formulation (1-98, 28-04) and particle size range (250-315μm for 1-98 and 28-04a, 315-500μm for 28-04b). Dissolution of the porous glass structure and its effect on pH was measured. Structural 2D and 3D analysis of porous structures were performed. Cell culture experiments were carried out to study keratocyte adhesion and the inflammatory response induced by the porous glass materials. The dissolution results suggested that the porous structure made out of 1-98 dissolves faster than the structures made from glass 28-04. pH experiments showed that the dissolution of the porous glass increased the pH of the surrounding solution. The cell culture results showed that keratocytes adhered onto the surface of each of the porous glass structures, but cell adhesion and spreading was greatest for the 98a bio-glass. Cytokine production by all porous glass samples was similar to that of the negative control indicating that the glasses do not induce a cytokine driven inflammatory response. Cell culture results support the potential use of synthetic porous bio-glass as an OOKP skirt material in terms of limited inflammatory potential and capacity to induce and support tissue ingrowth.

Thermodynamic Prediction of Spinodal Decomposition in Multi-component Silicate Glass for Design of Functional Porous Glass Materials

AbstractThe authors have investigated metastable phase separation in multi-component silicate glass for the fabrication of porous glass from multi-component slag. Spinodal decomposition forms an interconnected microstructure in glass spontaneously, and porous glass is obtained by leaching one of the decomposed phases with an acid solution. This porous glass can be used for a filter to remove impurities in polluted water or air. In this study, the metastable miscibility gap was predicted in multi-component silicate glass using thermodynamic analyses where glass was regarded as a super-cooled liquid phase. Occurrence of spinodal decomposition was observed in annealed glass, and it corresponded to the predicted miscibility gap. Then, we fabricated porous glass using spinodal decomposition in multi-component borosilicate glass and by removing one of the decomposed phases. Furthermore, for the creation of functional porous glass applicable for environmental purification, the spinodal decomposition was prepared in multi-component borosilicate glass containing titanium oxide based on the predicted metastable miscibility gap in multi-component silicate glass.

Bio-templated synthesis of mesoporous bioactive glass with a hierarchical pore structure

The bimodal porous structured mesporous bioactive glass (MBG) materials consisting of macropores were prepared using the natural Mediterranean sea sponge as macropored hard templates and P123 as mesopore soft templates, respectively. The macroporous structures of the natural Mediterranean sea sponge as macropored were replicated with the walls containing highly ordered MBG as well. Dexamethasone (DEX) was employed as a model drug and the release profiles showed that the dual porous materials had a sustained drug delivery capability. In addition, the materials had higher ability to induce hydroxycarbonate apatite (HAp) formation. Therefore, such highly ordered dual pore MBG materials might be used as a bioactive drug release system for preparation of bone implant materials.

Dielectric and mechanical relaxations in the vicinity of glass transitions in confined polar copolymers VDF/Te and VDF/Tr

The low-frequency elastic and dielectric properties of composite materials prepared by embedding of vinylidene fluoride–tetrafluoroethylene (V DF88/Te12) and vinylidene fluoride–trifluoroethylene (V DF60/Tr40) polar copolymers in porous glass matrices with a mean pore diameter of around 320 nm were investigated in the temperature range 150–330 K. Maxima of internal friction have been found near the glass transition temperatures Tg1 and Tg2 of the polymer amorphous fraction. Strong dielectric relaxation with characteristic time corresponding to the Williams–Landel–Ferry law was observed in the vicinity of temperature Tg1. An increase (≈10 K) of Tg1 temperature of the amorphous fraction of incorporated polymeric materials was detected. It was found that the low-frequency dielectric and mechanical losses in the vicinity of Tg1 are due to the same mechanism.

Preparation of highly porous cellular glass materials in the field of pyroxene crystallization

The work is devoted to sintering amorphous crystallizing glasses by slip technology with the aim of preparing highly porous cellular materials. Data are presented for the dependence of the intensity of diopside-like phase precipitation on the type of material subjected to crystallization. Attention is devoted to preparing and developing microstructure and physicochemical properties for specimens obtained after heat treatment. The materials developed may be used as substrates for catalysts of various physicochemical processes.

多成分系ガラスにおける分相現象の解析および同手法を利用した微細孔材創製の材料設計

多成分系ガラスにおける分相現象の解析および同手法を利用した微細孔材創製の材料設計

Dielectric relaxation in VDF60/Tr40 and VDF88/Te12 polar copolymers embedded in porous glass matrices

The dielectric properties of composite materials prepared by embedding P(VDF60/Tr40) and P(VDF88/Te12) polar copolymers in porous glass matrices with a mean flow-through pore diameter of around 320 nm were investigated in the temperature range 200–450 K. Strong dielectric relaxation, the characteristic time of which conformed to the Williams-Landel-Ferry law, was observed in the vicinity of glass transition point Tg of an amorphous fraction of polymer inclusions. An increase (≈10 K) in the Tg temperature of the amorphous fraction of incorporated polymeric materials was detected.