Characterization of glass surface damaged by alumina abrasive grains

The quality of an optical glass component is influenced by the presence of surface and subsurface defects generated by machining processes, especially lapping. However, the damaged area is characterized by roughness and crack layers that contribute to reduce the component's mechanical and optical performances. Evaluation of these defects leads to the obtainment of the best finishing technique for optical glass components.In this work, the effect of the lapping technological parameters (lapping time and alumina abrasive grain size) on the glass surface roughness as well as the depth of the damaged layer were determined. Furthermore, a proportionality constant between the total height of the roughness profile (Rt) and the subsurface damage layer was calculated. The damaged depth was characterized using mechanical techniques and microscopic analysis. The obtained results show an important damage of the glass surface, since the first few seconds of contact time between the surface and the grains. The increase of the lapping time gives rise to the propagation of this damage to reach its maximum and then a material removal rate is observed. At the end of the operation, a defined final surface roughness and a subsurface damaged layer are obtained. The proportionality constant between the subsurface damage layer and the total height of the roughness profile (Rt) was found to be 6.7 ± 0.8.     

Ion-beam deposition of tourmaline film on glass

Ion-beam deposition of tourmaline on glass substrate was investigated. X-ray fluorescence has been used to characterize surface composition of glass before and after deposition. The surface morphologies of glass were investigated by atomic force microscope. The crystallographic properties of the prepared films were evaluated by X-ray diffraction. Fourier infrared spectroscopy was used to determine infrared transmission. It is concluded that symmetrical island structure tourmaline film can be deposited on the glass substrate. The average size of the tourmaline grain is about 1 μm.     

Creep characterization of alumina particulate reinforced alumino-silicate glass

Compressive creep studies on alumino-silicate glass reinforced with alumina powders of 0.2 μm particle size as a function of volume fraction showed that there was a significant increase in the creep resistance by about an order of magnitude in the 20 vol.% composite. In order to study the effect of particle size on creep resistance, composites reinforced with 20 vol.% of 1.2 and 6.5 μm alumina particle size were also characterized. It was found that the composite with 1.2 μm particle sized reinforcement gave the highest creep resistance. All the composites exhibited Newtonian viscous creep and showed no strain hardening even at strains up to 10%.     

Surface biofunctionalization of nanostructured GeSbSe chalcogenide glass thin films

Thin nanostructured chalcogenide films were grown using the oblique angle deposition (OAD) technique and subsequently polymerized with thin poly(amino-p-xylylene) (PPX) films. Our objective was twofold, i.e., to use deposited polymeric thin films to allow the attachment of biomolecules to chalcogenide glass thin films, and at the same time, to increase surface area by OAD to enhance surface functionality. The effectiveness of this approach was evaluated by Fourier transform infrared spectroscopy (FTIR), together with a combination of fluorescent protein immobilization and confocal microscopy characterization. It is shown that the presence of amine groups on the surface of the polymer coated chalcogenide thin films yield a notable increment of surface coverage with proteins at large evaporation oblique angles which is expected to enhance detection performance of the film in biosensor applications.     

Electron beam probing of silica surface layers on alumina

The electron beam induced self-consistent charge injection and transport in a layered insulator SiO₂–Al₂O₃ is described by means of an electron–hole flight–drift model FDM and an iterative computer simulation. Thermal and field-enhanced detrapping are included by the Poole–Frenkel effect. The surface layer with a modified electric surface conductivity is included which describes the surface leakage currents. Furthermore, it will lead to particular charge incorporation at the interface between the surface layer and the bulk substrate. As a main result the time-dependent spatial distributions of currents j(x,t), charges ρ(x,t), field F(x,t), and potential V(x,t) are obtained. The spatial charge distribution with depth shows a quadro-polar plus–minus–plus–minus structure in nanometer dimension.     

Superscratch-resistant glass by means of a transparent nanostructured inorganic coating

Silica nanoparticles were synthesized by a reverse microemulsion method and deposited on soda-lime silica substrates. The deposition of these nanoparticles by dip-coating gave rise to close-packed layers, which significantly modify the scratch resistance of the surface. The silica nanoparticles are found to spread out the stress at the surface/indenter contact and to favor microductile behavior.     

Influence of carbon contamination on etched GaSb substrate on the quality of MBE-GaSb film and electrical transport through the film and the substrate

Undoped MBE-GaSb films were grown on undoped GaSb (100) substrates and the influence of carbon contamination on the etched GaSb substrate on the grown film were investigated. It was found that carbon contamination of the etched GaSb substrate was dependent on the chemical treatment method and produced stacking faults in the subsequent MBE growth of the GaSb film. Carbon contamination on the etched GaSb substrate degraded the quality of the GaSb film and affected ohmic characteristics between the film and the substrate. Substrate surface free of carbon contamination and thereby exhibitting no influence on the electrical transport through the film and the substrate could be reproducibly obtained by performing an oxide etch-off chemical treatment on the GaSb substrate.     

Influence of alumina addition on crystallization and texturing behavior of LaBGeO5 glass

The structure and crystallization behavior of glasses with 25La₂O₃ · 25B₂O₃ · 50GeO₂ composition, melted in platinum (P glass) and corundum (A glass) crucibles, were studied by DTA, X-ray diffraction and FTIR spectroscopy. The Al₂O₃ dissolved from corundum crucible in the A glass was estimated to be in the range 5–7 wt%. This alumina content had almost no influence on glass transition temperature but strongly affected the structure and crystallization behavior of the A glass. In fact, the P glass showed good texture-forming ability: high quality textured glass-ceramic plates based on stillwellite-like LaBGeO₅ crystals were easily obtained. On the contrary, the presence of alumina stabilized the A glass from which binary phases crystallize first, and only afterwards they are transformed in stillwellite by secondary crystallization: so in this glass texturing is hindered. Crystallization and texturing behavior of P and A glasses were well related to FTIR data. P glass contained both threefold and fourfold coordinated boron while in the A glass the presence of aluminum forced boron to assume almost exclusively threefold co-ordination. Hence the easier crystallization of stillwellite phase and the good textures obtained from the P glass contrary to the A glass, can be well understood since all boron atoms have tetrahedral co-ordination in stillwellite LaBGeO₅ crystal.     

Deposition of amorphous fluorosilane thin film on silicon surface: Atomic simulation

We utilized the Tersoff–Brenner potential form potential to investigate SiF₃ continuously bombarding silicon surface with energies of 10, 50 and 100 eV at normal incidence and room temperature by molecular dynamics method. The saturation of deposition yield of F and Si atoms on the surface is observed. A F-containing amorphous layer is formed whose thickness increases with incident energy. In the ejected gas-phase species, F, SiF and SiF₂ species increases with increasing incident energy, while the amount of SiF₃ species decreases.     

Redox profile of the glass surface

The redox profiles of tin, iron and sulfur at the float glass surface were determined on purposely cut samples by Electron Probe Micro Analysis (EPMA), X-ray Fluorescence mapping and X-ray Absorption Spectroscopy (XAS) at the micron scale. Going inward from the surface to the bulk, it was observed that (features do not depend on the glass thickness (holding time) though they extend over depths that vary from ca. 25 to 50 μm): (i) after a diffusion-driven decrease and prior to vanishing, the tin concentration passes through a local maximum (the tin hump), where stannous ions, which dominate the shallow layers, switch to stannic ions; (ii) the iron concentration decreases, passes through a minimum at the tin hump where iron is in the more reduced form (lowest Fe³⁺/Fe²⁺ ratio); it then increases and, after a hump which appears as a chemical echo of the tin hump, it reaches the bulk value; (iii) the concentration of sulfur increases up to reach the bulk concentration beyond the tin hump region. In a mixed S⁶⁺/S^2? form at the surface, sulfur is only in sulfate form in the bulk.In the case under study, the iron concentration is much too low to balance the redox reaction Sn²⁺ → Sn⁴⁺ that occurs at the tin hump. Sulfur is shown to play the role usually attributed to iron, according to the reaction4Sn²⁺ + S⁶⁺ → 4Sn⁴⁺ + S^2?The occurrence of that reaction is supported by the appearance of sulfide S^2? in the tin hump region with an appropriate concentration profile of a much stronger S^2?/S⁶⁺ ratio on the tin side than on the atmosphere side of the float glass. The conclusions drawn herein likely apply to the many cases in which the glass composition is similar as that encountered herein.     

Influence of surface topography on the multilayer film formation

The relationship between the topography of substrates and multilayer films deposited on these substrates (which are used in ring laser gyroscopes) has been investigated. The surfaces were studied by atomic-force microscopy. The statistical properties of the surface topography are analyzed within the approach based on a comparative analysis of the power spectral density functions of roughness calculated for the substrate and film. The degree of correlation between the substrate nanotopography and multilayer film is determined, and the influence of the substrate roughness on the optical characteristics of the deposited mirrors is established.     

The field-assisted penetration of a silver film into glass

The application of a DC field to a sodium-containing glass plate coated with a silver film causes Ag⁺ and Na⁺ ions to move toward the cathode, retaining the transparency of the glass. Characteristics of the process have been experimentally studied from various viewpoints: current and voltage versus time, fluorescence generation/annihilation, refractive index increase, spectral reflectivity characteristics, internal strain generation, volume increase, the weight of penetrated silver versus transported electric charge and concentration profiles. The dynamics of the process have been shown to be approximately linear. The linearity is considered to come from the following: (1) the resistance of a Ag-penetrated layer is much smaller than that of the whole of a glass plate and (2) Na⁺ ions are not piled up in the vicinity of the cathode-side surface.     

Silicon on spinel: The interaction between deposition constituents and the substrate surface

The examination of the growth of silicon on flame fusion and Czochralski spinel prior to complete coverage of the substrate provides information on the chemical interaction between the deposition constituents and the substrate material. The flame fusion spinel appears to be eroded primarily by silicon, while the Czochralski spinel is eroded by both hydrogen and silicon. The hole mobilities in (111) silicon deposited in helium on the Czochralski spinel are similar to the mobilities in (111) silicon deposited in hydrogen on the flame fusion spinel. The semiconducting properties of silicon on the Czochralski spinel are degraded by annealing the substrate in hydrogen, and are unaffected by annealing the substrate in helium. The substrate surface work damage appears to be removed as the result of reduction of the spinel by silicon during the deposition of silicon on the Czochralski spinel in helium. Both the electrical data of 1 μm thick films and the physical nature of the deposits prior to complete coverage of the substrate lead to the conclusion that the hole mobilities in silicon on spinel are limited primarily by the impurities introduced into the deposit by reaction of the substrate with the deposition constituents, and that the impurities are incorporated into the deposit mainly prior to complete coverage of the surface and are concentrated in a thin layer in the silicon near the silicon-substrate interface.     

Silicate nanoparticles by bioleaching of glass and modification of the glass surface

Bioleaching is examined as a low temperature (50 °C) soft chemical approach to nanosynthesis and surface processing. We demonstrate that fungus based bioleaching of borosilicate glass enables synthesis of nearly monodispersed ultrafine (∼5 ± 0.5 nm) silicate nanoparticles. Using various techniques such as X-ray diffraction, X-ray photoelectron spectroscopy and FTIR we compare the constitution and composition of the nanoparticles with that of the parent glass, and establish the basic similarities between the two. The bioleaching process is shown to enhance the non-bridging oxygen component and correspondingly influence the Si-O-Si network. The root mean square roughness of glass surface is seen to increase from 1.27 nm for bare glass to 2.52 nm for 15 h fungal processed case, this increase being equivalent to that for glass annealed at 500 °C.     

A new approach to thin film crystal silicon on glass: Biaxially-textured silicon on foreign template layers

We propose a new approach to growing photovoltaic-quality crystal silicon films on glass. Other approaches to film Si focus on increasing grain size in order to reduce the deleterious effects of grain boundaries. Instead, we propose aligning the silicon grains biaxially (both in and out of plane) so that (1) grain boundaries are ‘low-angle’ and have less effect on the electronic properties of the material and (2) subsequent epitaxial thickening is simplified. They key to our approach is the use of a foreign template layer that can be grown with biaxial texture directly on glass by a technique such as ion-beam-assisted deposition or inclined substrate deposition. After deposition of the template layer, silicon is then grown aligned to the template and subsequently thickened. Here, we outline this new approach to silicon on glass, describe initial experimental results and discuss challenges that must be overcome.     

Ion beam modification of glass surface properties

This paper presents a general review of the effects, including H decoration of defects, induced by ion implantation of silicate and fluoride glasses. Ion implantation into glasses results in network damage and in compositional changes. Compositional changes are due to internal electric field formation, radiation enhanced diffusion processes and preferential sputtering, connected to different stopping power (electronic or nuclear) regimes of the incident particles. Such effects create modifications in the mechanical, optical and chemical properties of the glasses.     

Gas barrier characteristics of a polysilazane film formed on an ITO-coated PET substrate

With the aim of developing a high-performance gas barrier material, a polysilazane film was applied to an indium tin oxide (ITO)-coated organic PET substrate (i.e., the ITO and polysilazane films were formed sequentially on the PET substrate), and its properties were evaluated. The resulting material exhibits favorable gas barrier characteristics (oxygen permeability 0.02 cc/m² day, water vapor permeability 0.15 g/m² day) and performs well as a gas barrier. By controlling the atmosphere during heat treatment when forming the polysilazane film, it is possible to form a highly transparent film with good gas barrier performance. Since this material also conducts electricity due to the presence of the ITO film, it can be used to implement various advanced functions.     

Effect of surface treatments on the chemical durability and surface composition of soda-lime glass bottles

Chemical analyses show that water and 1% KHCO₃ solutions extract material that resembles the bulk glass composition for both untreated and treated soda-lime bottles although much less material is extracted from treated bottles. Also, fluorine appears to be deeply dispersed at perhaps 1% concentration in a fluorocarbon-treated glass surface. Electron spectra obtained before and after ion milling detected no fluoride and indicated calcium and some sodium depletion for fluorocarbon-treated surfaces, and a depletion of calcium as well as sodium for sulfur-treated surfaces. There also is evidence from electron spectra of some sodium and calcium depletion in untreated glass surfaces.     

The pentacene films on the glass/ITO surface: structure and optical properties

Abstract

The structure, morphology and optical transmittance spectra of pentacene films on the (glass/ITO) surface were studied. The films were grown by two methods - the thermal vacuum deposition (TVD) and pulsed laser deposition (PLD). The electron diffraction pattern from thermally deposited pentacene films confirms their polycrystalline structure while the diffraction pattern of PLD-coated layers has a diffusion character. The results obtained showed that layers deposited by the TVD method has an optical spectrum that is characteristic for the pentacene film in contrary to the layers deposited by the PLD method. It is found a sensitivity of the optical transmittance of pentacene films to the ammonia action, which may be used for development the optical gas sensor.     

The surface layer formed on zinc-containing glass during aqueous attack

The glass-water interaction is reviewed via an outline of the processes of bulk dissolution, selective leaching and surface enhancement. Special attention is paid to the nature and effects of surface films. Glasses of three compositions, each containing about one-fifth by weight Zn, are subjected to aqueous attack. Solution analysis confirms the roles of Na, Si and Zn in leaching, dissolution and surface enhancement, respectively. Proton-induced X-ray emission corroborates Zn enhancement in the glass surface and X-ray photoelectron spectroscopy fixes the Zn build-up to the first few nanometres. Powder X-ray diffraction examination identifies the specific structures of hemimorphite and Zn orthosilicate while transmission electron microscopy finds such phases to be distributed in a largely amorphous matrix. Infrared spectra are consistent with the presence of a modified silicate structure and additionally indicate that water is loosely bound in the reacted surface layer. Attack of a non-Zn glass by a Zn-containing solution shows the ion in solution produces a Zn surface layer while attack of a Zn glass by a Zn complexing solution shows a Zn layer forms preferentially to complexation. Hence Zn, in either the solid or solution, induces a thin, protective, solvated and partially crystalline silicate zone on a glass under aqueous attack.