Ion-exchanged Glass Research Articles

Surface modification of ion-exchanged float aluminosilicate glass during deposition of amorphous alumina coatings by e-beam evaporation

The main objective of this study was to investigate the physico-chemical and mechanical properties of ion-exchanged float aluminosilicate glasses deposited the Al2O3 films. The concentration gradients of potassium (K), sodium (Na), aluminum (Al) and oxygen (O) elements near Al2O3 film/ion-exchanged glass interface were analyzed by electron probe X-ray micro-analyser (EPMA). Compared with the ion-exchanged glasses, the peak of potassium concentration profile in the ion-exchanged glasses deposited Al2O3 films decreases and moves from glass surface to the inner part. Potassium ion diffusion is accompanied by aluminum (Al) and oxygen (O) diffusion from Al2O3 film into the ion-exchanged glass during deposition. In-depth analyses are performed using micro-Raman spectroscopy on sample cross sections in the aim to investigate the microstructure variation of the ion-exchanged glasses after deposited Al2O3 film on it. The results show that the change of chemical composition throughout ion-exchanged glass surface region can cause a gradual change in microstructure and physical properties.

Nanoscale self-arranged layers of silver nanoparticles in glass

We characterized changes in the composition of subsurface layer of silver ion-exchanged soda-lime glass during annealing in hydrogen atmosphere. The formation of tens of nanometers distanced layers of silver nanoparticles in the glass at temperature of 300°C has been revealed. Performed numerical modeling of the process demonstrates a good qualitative agreement with the experiment. This is of interest for simple formation of 3D-optoplasmonic structures, Bragg gratings or photonic crystals.

Mechanical–Structural Investigation of Ion-Exchanged Lithium Silicate Glass using Micro-Raman Spectroscopy

Micro-Raman spectroscopy was used to determine the structural modifications occurring in a simple ion-exchanged glass. The base lithium silicate composition 30Li2O–70SiO2 was studied as it underwent ion exchange, Li+ ↔ K+, at six temperatures spanning the glass transition point. Using a well-developed relationship between the Si–O–Si bond angle, the Si–O bond length, and Raman shifts, the reduction in network molar volume and increase in compressive stress were estimated. On the basis of the effect of the ion-exchange temperature, the existence of a threshold energy below which the compressive stress manifests as the reorientation of silica tetrahedra only and above which the system relaxes by increasing the Si–O bond length is proposed. Finally, the linear network dilation coefficient is revisited in terms of these new data and an explanation given for its underestimation and overestimation of stress at low and high temperatures, respectively.

Nanoindentation Study of the Surface of Ion-Exchanged Lithium Silicate Glass

Variations in mechanical properties (stiffness and hardness) were measured as a function of case depth in ion-exchange glasses using nanoindentation. A simple silicate composition, 30Li2O–70Si2O, was exchanged (Li+ ↔ K+) at several different temperatures, below and above the glass transition, to evaluate the effect of exchange temperature on mechanical properties throughout the ion-exchange layer. Significant enhancements in Young’s modulus and hardness were found near the edge in ion-exchanged glasses and attributed to compressive stress and the mixed-alkali effect. Indent size effect-like behaviors were observed in the untreated and ion-exchange samples alike near the sample edge; this was explained by surface-condition sensitivity and compressive stress found within this region. The elastic recovery and resistance to plastic deformation were calculated to assess the effect of ion exchange on elastic and plastic mechanical responses. Microhardness measurements of the exchanged samples were also made for...

2D-patterning of self-assembled silver nanoisland films.

The paper is dedicated to the recently developed by the authors technique of silver nanoisland growth, allowing self-arrangement of 2D-patterns of nanoislands. The technique employs silver out-diffusion from ion-exchanged glass in the course of annealing in hydrogen. To modify the silver ion distribution in the exchanged soda-lime glass we included the thermal poling of the ion-exchanged glass with a profiled electrode as an intermediate stage of the process. The resulting consequence consists of three steps: (i) during the ion exchange of the glass in the AgxNa1-xNO3 (x = 0.01-0.15) melt we enrich the subsurface layer of the glass with silver ions; (ii) under the thermal poling, the electric field displaces these ions deeper into the glass under the 2D profiled anodic electrode, the displacement is smaller under the hollows in the electrode where the intensity of the field is minimal; (iii) annealing in a reducing atmosphere of hydrogen results in silver out-diffusion only in the regions corresponding to the electrode hollows, as a result silver forms nanoislands following the shape of the electrode. Varying the electrode and mode of processing allows governing the nanoisland size distribution and self-arrangement of the isolated single nanoislands, pairs, triples or groups of several nanoislands-so-called plasmonic molecules.

Strengthening of borosilicate glass by ion exchange for advanced ballistic impact behaviour

Borosilicate glass was reinforced via ion exchange to improve the ballistic impact resistance of transparent bulletproof materials. The optimal heat treatment conditions of ion-exchanged borosilicate glass with thicknesses of 4, 6 and 8 mm were 12, 15 and 17 min at 560°C, respectively. The flexural strengths of the reinforced glasses were 0.783 ± 0.018, 0.810 ± 0.014 and 0.835 ± 0.013 GPa, respectively. This improved on that of the parent material by a factor of 2.5. Light transmittance exceeded 91.1%. The bulletproof materials comprised one polycarbonate sheet, two multilayer defence films and strengthened glass. The thickness of the bulletproof material decreased by ~18%, from 28.80 mm for the original glass to 23.65 mm for the strengthened glass. The ballistic limit velocity improved by 14% from 851 (V50) to 972 (V0) m/s. The light transmittance of the material was 86.2%, confirming its potential use as a transparent bulletproof material.

Self-organized growth of small arrays of metal nanoislands on the surface of poled ion-exchange glasses

Self-organized metal nanostructures have been obtained by an original method on the surface of soda–lime glasses. The nanostructures are grown by heat treatment of poled glass substrates in hydrogen upon preliminary ion-exchange introduction of silver. The poling is produced with the aid of a profiled anode electrode. Using the proposed method, it is possible to grow separate metal nanoislands and ordered nanostructures of several islands on the glass surface. The islands are formed in submicron-sized unpoled regions as a result of self-assembly during out-diffusion of silver. Minimum spacing in linear groups of two or three silver islands is 20–30 nm at their characteristic size of about 100 nm. The proposed method allows nanoisland arrays and groups of a few islands to be grown and multiplicated.

二段階イオン交換ガラスにおける応力プロファイル測定方法の開発

二段階イオン交換ガラスにおける応力プロファイル測定方法の開発

Mechanical model to simulate buildup and relaxation of stress during glass chemical strengthening

A mechanical model comprising Hookean springs and Newtonian dashpots in a series configuration of a Maxwell element and a Voigt–Kelvin element is used to simulate the buildup and relaxation of stresses during ion exchange of glass. The spectrum of time constants for the dashpots spans from picoseconds to years. Good consistency is developed with molecular dynamic simulations published earlier.

Influences of preparation conditions on the formation and depth dispersion of Ag nanoparticles in soda–lime silicate glass

Influences of preparation conditions on the formation and depth dispersion of Ag nanoparticles in soda–lime silicate glass were systematically studied by using ultraviolet–visible (UV–vis) spectrophotometer, X-ray photoelectron spectroscope (XPS), electron microprobe analyzer (EMA) and transmission electron microscope (TEM). The results indicate that the dispersed depth of Ag nanoparticles mainly depends on the diffusion depth of Ag+ ions in the ion-exchanged glass, and Ag nanoparticles have a reduced volume-filling fraction (VFF) along the depth. The VFF of Ag nanoparticles increases with increasing the concentration of Ag+ ions in the glass, the annealed temperature and/or the annealed duration. Ag nanoparticles form easier in Fe-containing glass than in Fe-free glass. Annealing the ion-exchanged glass in H2 atmosphere favors the formation of Ag nanoparticles at a lower temperature and a shorter duration than in air. Ag nanoparticles display a narrow size distribution of 1–6nm in the annealed sample in air and a broad size distribution of 1–30nm in the annealed sample in H2 atmosphere. The formation mechanism of Ag nanoparticles in the ion-exchanged glass is discussed in detail.

Control of surface plasmon resonance in out-diffused silver nanoislands for surface-enhanced Raman scattering

We present the studies of self-assembled silver nanoislands on the surface of silver ion-exchanged glasses. The nanoislands were formed by out-diffusion of reduced silver atoms from the bulk of the glass to its surface. Control of silver ions distribution in the glass by thermal poling after the ion exchange allowed formation of relatively big, up to 250 nm, isolated silver nanoislands while without the poling an ensemble of silver nanoislands with average size from several to tens of nanometers with random size distribution was formed. The nanoislands were characterized using atomic force microscopy and spectral measurements. We used optical absorption spectroscopy for “random” nanoislands and dark field scattering spectroscopy for isolated ones, corresponding spectra showed peaks in the vicinity of 450 nm and 600 nm, respectively. The “random” nanoislands significantly enhanced Raman scattering from Rhodamine 6G, also the modification of Raman signal from deposited on the surface of the samples bacteriorhodopsin in purple membranes was registered.

Formation of metallic nanostructures on the surface of ion- exchange glass by focused electron beam

This paper presents a new method for formation of metallic nanostructures on the surface of ion-exchange glass. The method is based on the interaction of a focused electron beam with ions in ion-exchange glass. In experiments nanostructures with different shapes were obtained, depending on the electrons irradiation conditions.

Modes of silver nanoisland film growth on the surface of ion- exchanged glass

The behavior of silver nanoisland film growth on the surface of ion-exchanged glasses processed in the air and in hydrogen atmosphere is compared. The films grown in air degrade with the increase of processing time because of oxidizing. The growth of the film in hydrogen atmosphere tends to saturate with time due to the decrease in the flow of atomic silver towards the glass surface. This is because of the formation and growth of silver nanoparticles in the bulk of the glass, these nanoparticles being the preferable sink for silver atoms.

Dynamics of laser-induced radial birefringence in silver-doped glasses.

Silver ion-exchanged glass exhibits nonlinear optical properties upon interacting with intense light beams. The thermal effect due to the nanoparticles' light-absorption induces radial stress, and consequently, a radial birefringence on the glass surface. The induced birefringence possesses a topological charge of 1 in the transverse plane of the glass, i.e., cylindrical symmetry. Therefore, when the glass is illuminated with a circularly polarized light beam, a portion of the incoming beam flips its polarization handedness, since the plate is birefringent, and gains an orbital angular momentum of ±2 in units of the Planck constant. This is referred to as optical spin-to-orbital angular momentum conversion, and can be understood by means of the Pancharatnam-Berry phase. Here, we design a pump-probe setup to study and observe the dynamics of optical angular momentum coupling in real time. We show that this effect can be permanent or reversible, depending on the power and interaction time of the pump beam. In particular, an intrinsic power-dependent birefringence hysteresis is observed on the sample after interaction with and the relaxation of the irradiated point.

The influence of the conditions of ion exchange in CuSO4:Na2SO4 melt on the optical properties of surface layers of silicate glass

The influence of the temperature and duration of ion exchange in BK7 silicate glass in CuSO4:Na2SO4 melt on the optical properties of the glass surface layers has been investigated. It is shown that ion exchange occurs from the melt according to the Cu2+ ↔ 2Na+ scheme. Cu2+ ions penetrate the sample to a depth of about 1 µm. Reduction of Cu2+ ions near the glass surface gives rise to the Cu+ ↔ Na+ ion exchange in the glass. Measurements of refractive index profiles in the glass sample subjected to ion exchange have revealed the formation of two waveguides in the sample: near the surface and at a depth of more than 3 µm; the second waveguide is formed by Cu+ ions. It is shown that relatively low temperatures and short durations of ion exchange lead to the formation of copper molecular clusters Cun in glass. An increase of ion exchange temperature and duration leads to decomposition of molecular clusters with formation of Cu2+ ions.

Broadband Graphene/Glass Hybrid Waveguide Polarizer

In this letter, a broadband planar-lightwave-circuit-type graphene/glass hybrid waveguide polarizer has been demonstrated. The polarizing effect of the polarizer is based on the difference in the attenuation between the two orthogonally polarized guided modes. The buried depth and the width of the ion-exchange glass waveguide are optimized to 2.6 and $11.5~\mu \text{m}$ , respectively. The polarization extinction ratio of the polarizer is $\sim 27$ dB in the telecommunication band with $\sim 4$ -mm graphene coating length along the propagation direction. In addition, the polarization extinction ratio can be further increased by decreasing the chemical potential of the graphene film.

Grazing incidence small angle X-ray scattering study of silver nanoparticles in ion-exchanged glasses

The size and distribution of silver nanoparticles in ion-exchanged silicate glass induced by thermal treatments in air at different temperatures were investigated by means of grazing incidence small angle X-ray scattering technique, X-ray diffraction and optical absorption spectra. Silver–sodium ion exchange of soda-lime silicate glasses was done at 350°C for 240min, then the samples were treated by thermal annealing in air at different temperatures 400, 500 and 550°C, respectively, for 1h. After the annealing treatment above 400°C for 1h, smaller Ag nanoparticles occurred, together with bigger ones. Both dissolution of smaller Ag nanoparticles and diffusion of larger ones are discussed in these stages of annealing in this contribution.

Chromatic characterization of ion-exchanged glass binary phase plates for mode-division multiplexing.

Mode-division multiplexing (MDM) in few-mode fibers is regarded as a promising candidate to increase optical network capacity. A fundamental element for MDM is a modal transformer to LP modes which can be implemented in a free-space basis by using multiregion phase plates, that is, LP plates. Likewise, several wavelengths have to be used due to wavelength multiplexing purposes, optical amplification tasks, and so on. In this work we show that efficient monolithic binary phase plates for different wavelengths can be fabricated by ion-exchange in glass and used for MDM tasks. We introduce an optical characterization method of the chromatic properties of such phase plates which combines the inverse Wentzel-Kramers-Brillouin (IWKB) together with Mach-Zehnder and Michelson-based interferometric techniques. The interferometric method provides a measurement of the phase step for several wavelengths, which characterizes the chromatic properties of the phase plate. Consequently, it is shown that the IWKB method allows us to design and characterize the phase plates in an easy and fast way.

Interferometric angular characterization of ion-exchanged glass binary phase plates

An interferometric characterization of the phase angular shifting produced by rotation of an ion-exchanged glass binary phase plates is presented. The inverse WKB method is used as a starting point to fabricate the phase plates, because such a method can only characterize the phase shift for normal incidence of the light on the plate. A complete phase angular shifting characterization is made by a Mach-Zehnder interferometer where a four-step phase shifting method is used for acquisition of data and a modified Carre algorithm is applied to data processing. The theoretical phase shifting is calculated by using the phase accumulated by a plane wavefront propagating in an axial graded-index media modelling an ion-exchanged glass phase plate. Experimental results present a good agreement with theoretical predictions.

Development of a transparent, non-cytotoxic, silver ion-exchanged glass with antimicrobial activity and low ion elution

We investigated the antimicrobial, cytotoxicity, skin irritation, and ion elution behaviors of glass doped with silver ions with respect to its application to electronic equipment such as phones and tablet screens. The microbes tested were Escherichia coli, Staphylococcus aureus, and Penicillium funiculosum. AgNO3 powder was spread on both sides of aluminosilicate glass, and it was heated to 250–280°C for 10min. Under optimized heating conditions (260°C, 10min), the antimicrobial activity of ion-exchanged glass against bacteria and fungi was over 99.9% after 24 weeks. The glass failed to irritate the skin of experimental animals and was considered non-cytotoxic. The maximum amount of Ag ions that were eluted from the ion-exchanged glass into drinking water was measured at 0.037±0.003μgL−1, an amount which is several orders of magnitude below the standard limit of 0.1mgL−1 in drinking water. Ag ion-exchanged glass had characteristics suitable for use as a display screen, such as a light transmittance of 90% and a surface roughness of 0.704nm. Our findings suggest that glass doped with silver ions is more hygienic than non-doped glass is, and should be applied to display screens and glassware.