Ion-exchanged Glass Research Articles

Gain anticipation of Ho3+ in ion-exchangeable germanate waveguide glasses

Efficient infrared emissions at ~ 1.2 and ~ 2.0 µm were recorded in Ho3+-single-doped and Ho3+/Yb3+-co-doped aluminum germanate glasses (NMAG), respectively. The maximum stimulated emission cross-sections for the ~ 1.2- and ~ 2.0 µm emissions were derived to be 2.3 × 10−21 and 5.8 × 10−21 cm2, respectively; then the gain cross-sections were further evaluated and the effective gains have been anticipated. In addition, the channel waveguide fabricated by K+–Na+ ion-exchanged method exhibited a complete single mode at 1.55 µm and the field diameters were identified to be horizontally 10.6 µm and vertically 6.7 µm. Effective amplified spontaneous emission at ~ 2.0 µm was recorded under 980 nm laser pumping. Broad bandwidth, large emission cross-section and perfect thermal ion-exchangeability indicate that Ho3+- and Yb3+-doped NMAG glasses are promising for the development of optical amplifier, tunable laser and light source operating at ~ 1.2 and ~ 2.0 µm.

Ag nanoaggregates as efficient broadband sensitizers for Tb3+ ions in silica-zirconia ion-exchanged sol-gel glasses and glass-ceramics

In this paper we report the study of down-shifting silica-zirconia glass and glass-ceramic films doped by Tb3+ ions and Ag nanoaggregates, which combine the typical spectral properties of the rare-earth-ions with the broadband sensitizing effect of the metal nanostructures. Na-Tb co-doped silica-zirconia samples were obtained by a modified sol-gel route. Dip-coating deposition followed by annealing for solvent evaporation and matrix densification were repeated several times, obtaining a homogeneous crack-free film. A final treatment at 700 °C or 1000 °C was performed to control the nanoscale structural properties of the samples, resulting respectively in a glass (G) or a glass-ceramic (GC), where tetragonal zirconia nanocrystals are surrounded by an amorphous silica matrix. Ag introduction was then achieved by ion-exchange in a molten salt bath, followed by annealing in air to control the migration and aggregation of the metal ions. The comparison of the structural, compositional and optical properties are presented for G and GC samples, providing evidence of highly efficient photoluminescence enhancement in both systems, slightly better in G than in GC samples, with a remarkable increase of the green Tb3+ PL emission at 330 nm excitation: 12 times for G and 8 times for GC samples. Furthermore, after Ag-exchange, the shape of Tb3+ excitation resembles the one of Ag ions/nanoaggregates, with a broad significant absorption in the whole UV-blue spectral region. This broadband enhanced downshifting could find potential applications in lighting devices and in PV solar cells.

Influence of different process conditions on mechanical, optical and surface properties of silver ion exchanged soda-lime silicate glass

Recently, surface modified functional glasses have been the focus of attention for researchers. Among the other surface modification methods, ion-exchange process has become prominent in terms of cost effectiveness of the process, ease of production, not causing damage to the glass matrix. The aim of this work is to investigate how certain ion exchange and further heat treatment processes affect the mechanical, optical and surface properties of soda-lime silicate glass. The glass samples have been subjected to ion exchange at 320 °C in a molten mixture of AgNO3 and NaNO3 with molar ratios of 2:98, 5:95, respectively and heat treatment under reducing atmosphere (Ar/H2 with a 5% H2 volume fraction mixture). The study is conducted in two parts. The first part involves a batch of characterization on the untreated and the treated glass samples. The characterizations include optical transmittance, absorbance and reflectance measurements by UV–vis-NIR spectrophotometer, FTIR analyses to examine surface properties. Scratch resistance with an increasing load and flexural strength measurements were conducted on the glass samples to determine the mechanical features of the glasses. The second part of the study includes the determination of possible corrosion mechanisms and optical properties changes of the glass surfaces after environmental test. Before and after the environmental test, optical transmission and colour analysis of the specimens were realized by UV–vis-NIR spectrophotometer, FTIR analyses were conducted on the surface of the silver ion-exchanged glass samples in order to observe corrosion reaction by using the reflection technique in the 400–4000 cm−1 wavenumber range. As a result of the study, glass samples with controllable optical, surface and mechanical properties by process parameters, containing silver nanoparticles and resistant to atmospheric conditions are obtained.

Elastic-plastic deformation in ion-exchanged aluminosilicate glass by loading rate dependent nanoindentation

The elastic-plastic deformation in raw and ion-exchanged aluminosilicate glass is investigated by loading rate dependent nanoindentation. The nanohardness and Young's modulus of the raw and ion-exchanged glasses at different loading rate (100–20,000 μN.s−1) are explored up to a maximum load of 9000 μN. The nanoindentations are scanned with AFM to observe the morphology of the indents. The results show that Young's modulus of the aluminosilicate glass increases after ion exchange and that the nanohardness of the raw and ion-exchanged aluminosilicate glass increases linearly with the loading rate, when plotted on a double logarithmic axes. However, the nanohardness of the raw glass is more sensitive to the variation of loading rate. The compressive stress on the ion-exchanged glass can inhibit plastic deformation. These results are explained in terms of shear stress underneath the indenter and the number of the flow lines in the nanoindentations. These findings are useful for better understanding the dynamic contact-induced damage growth mechanisms of ion-exchanged glass.

Electrical and mechanical properties of Na2.8Ca0.1Al2Ga0.5P2.7O12 glass based electrolyte materials: Influence of Ag+ ion-exchange

Sodium super ionic conductor (NASICON) based glass is emerging as solid electrolyte material for Na-ion batteries. In the present study, we report the influence of Ag+ → Na+ ion-exchange process on the electrical, optical, structural and mechanical properties of NASICON type glass with a chemical formula of Na2.8Ca0.1Al2Ga0.5P2.7O12 (NCAGP). Ag+ ion exchange process was carried out by dipping NCAGP glass in AgNO3 molten salt at 300 °C for 15 min (IE15min) and 30 min (IE30min). The diffusion depth of Ag+ ions was measured to be about ~7 μm and ~25 μm for IE15min and IE30min samples, respectively. The dc conductivity values were obtained from base (NCAGP), IE15min and IE30min bulk glass samples through the complex impedance plots at a temperature range of 75 °C–200 °C. With the increase in ion-exchange time, the dc conductivity slightly diminished on account of marginally increase in activation energy (Ea) values. Optical absorption spectra for 30 min ion-exchanged glass revealed the localized surface plasmon resonance (LSPR) band, confirming the reduction of Ag+ ion to Ag0 metal with an increase in ion-exchange time from 15 min to 30 min. Presence of Raman vibrational peak at 233 cm−1 has also confirmed the formation of AgO bonds. The mechanical hardness values obtained through Vickers indentation method reveal enhanced hardness and crack resistance of bulk glasses with the ion-exchange treatment by causing compressive stress on the surface of NCAGP glass. The threshold load for the crack generation is increased from 0.5 kgf (4.9 N) to 2 kgf (19.6 N) after the ion-exchange treatment. Overall, improved mechanical and good electrical properties reveal the applicability of IE15min NCAGP glass as an electrolyte material for Na-ion batteries.

Efficient magneto-optical TE/TM mode converter in a hybrid structure made with a SiO2/ZrO2 layer coated on an ion-exchanged glass waveguide

The TE-TM mode conversion is an important requirement for magneto-optical waveguide devices. In this work, we report on the theoretical study of magneto-optical waveguides on an ion-exchanged glass waveguide. This study explores the possibility to realize a mode converter TE-TM on a hybrid structure. This hybrid device is made by coating a SiO2/ZrO2 layer doped with magnetic nanoparticles on an ion-exchanged glass waveguide. It has been analyzed by means of a beam propagation method for numerical solution of the full-vectorial wave equation. We have also used the transparent boundary condition. The mode converters TE-TM based on the Faraday rotation and modal birefringence are then numerically simulated. Depending on the increasing of nanoparticles volume fraction in the SiO2/ZrO2 layer and on decreasing the modal birefringence of the hybrid structure, the TE-TM conversion efficiency varies from several percent to several tens of percent.

Topological Origin of the Network Dilation Anomaly in Ion-Exchanged Glasses

Although ion exchange is commonly used to strengthen oxide glasses, the products usually reach just a small fraction of their maximum theoretical strength, due to the so-called atomic network dilation anomaly. Based on molecular dynamics simulations, this study reveals that the dilation anomaly is topological in origin. Surprisingly, glasses exhibiting an optimal (isostatic) atomic topology are found to be free of this anomaly. These results establish topological nanoengineering as a promising route to designing ultrastrong glasses, with significant implications for industry---and your next mobile phone.

A XANES investigation of the network-modifier cations environment before and after the Na+/K+ ion-exchange in silicate glasses

μ-XANES is used to study the modifications in the alkali and alkaline-earth environments induced by the Na+/K+ ion-exchange process in various Na –silicate glasses. The results indicate that the ion-exchange process induces a shortening of the NaO, CaO and MgO bond distances. The contraction of the NaO, CaO and MgO coordination shell allows a better accommodation of the K+ cations in the glass network and thereby leads to partial relaxation of the stress developed by the Na+/K+ ion-exchange. Nevertheless, despite the stress relaxation process, the K+ environment in the ion-exchanged glass is not equivalent to the one in Na,K–silicate as-melted glasses. Hence, this study clearly shows that the ion swapping forced K+ cations to occupy smaller sites which are not achievable via the melt quench route for glasses with the same K amount.

Na+/K+ ion exchange in silicate glasses: Results from 17O 3QMAS NMR

The effect of Na+/K+ ion exchange on the distribution of the modifier ions and on their interaction with the oxygen atoms in the network is investigated in ternary Na,Mg- and Na,Ca- silicate glasses using 17O triple-quantum magic-angle-spinning nuclear magnetic resonance spectroscopy. The results indicate that the K+ ions preferentially exchange with the Na+ ions present in {Na,Ca}-NBO and {Na,Mg}-NBO environments, while the Na-NBO environment is not significantly affected. Remelting of the ion-exchanged glasses leads to a homogenization of the modifier ion distribution around the NBO sites. The dynamical site preference for the Na+/K+ ion exchange has far-reaching implications in our understanding of the alkali ion transport and more specifically of the mixed-alkali effect in silicate glasses.

Residual stress in ion-exchanged silicate glass: An analytical solution

The ion-exchanged residual stress profile influences both the strength and the wear-resistance of glass hence its description is of great importance. Currently, residual stress profiles of silicate glasses can only be estimated by numerical time-integration based on the known ionic concentration profile and the expected stress relaxation behavior of the glass. In this work, we derived and validated the constant coefficients analytical solution describing the residual stress profile in single-step ion-exchanged glasses. The proposed solution is based on Sane and Cooper's model and assumed that both the generalized Maxwell stress relaxation function applied and that a constant ionic inter-diffusion coefficient could accurately describe the behavior of the system. Furthermore, an analytical approximation for composition-dependent stress relaxation behavior of the glass was proposed. Examples of how the newly developed analytical description of the stress profile could be fitted through regression analysis to available residual stress data were also presented.

UV–Visible spectral conversion of silver ion-exchanged aluminosilicate glasses

Silver ion-exchanged was employed to introduce silver into the surface layer of aluminosilicate glasses. Effects of salt composition and annealing conditions on the distribution, valence and clustering states of silver were investigated through emission and excitation spectra measurement. It was found that isolated Ag+ ions, clusters of Ag2+ and Ag22+, and other mixed species of Ag+ ions and Ag0 atoms were present in the ion-exchanged glasses. Upon UV excitation (250–400nm), silver ion-exchanged glasses showed three distinct bands centers at 420nm, 480nm and 530nm, exhibiting great potential for the UV light down-shifting. Using the silver ion-exchanged glass as cover, quantum efficiency of α-Si solar cell in the 280–318nm spectral range was improved.

Trends in Effective Diffusion Coefficients for Ion-Exchange Strengthening of Soda-Lime-Silicate Glasses

Monovalent cations enable efficient ion exchange processes due to their high mobility in silicate glasses. Numerous properties can be modified in this way, e.g., mechanical, optical, electrical or chemical performance. In particular, alkali cation exchange has received significant attention, primarily with respect to introducing compressive stress into the surface region of a glass, which increases mechanical durability. However, most of the present applications rely on specifically tailored matrix compositions in which the cation mobility is enhanced. This largely excludes the major area of soda lime silicates (SLS) such as are commodity in almost all large-scale applications of glasses. Basic understanding of the relations between structural parameters and the effective diffusion coefficients may help to improve ion-exchanged SLS glass products, on the one hand in terms of obtainable strength and on the other in terms of cost. In the present paper, we discuss the trends in the effective diffusion coefficients when exchanging Na+ for various monovalent cations (K+, Cu+, Ag+, Rb+ and Cs+) by drawing relations to physico-chemical properties. Correlations of effective diffusion coefficients were found for the bond dissociation energy and the electronic cation polarizability, indicating that localization and rupture of bonds are of importance for the ion exchange rate.

High efficient luminescence of silver clusters in ion-exchanged antimony-doped photo-thermo-refractive glasses: Influence of antimony content and heat treatment parameters

Photo-thermo-refractive glass is now promising material for developing various elements and devices of photonics. The effect of variations in the Sb2O3 concentration in the photo-thermo-refractive glass composition on the spectral-luminescent properties of silver clusters formed with the low-temperature ion exchange is studied for the first time. The effect of temperature and duration of subsequent heat treatment of ion-exchanged glasses is investigated in detail. Silver clusters in the glasses are shown to possess broadband luminescence in the visible and NIR. Luminescent silver clusters in Sb-doped photo-thermo-refractive glasses reveal the absolute quantum yield up to 63% (λex=365nm), which can be used effectively for developing luminescent sensors, white LEDs, and down-convertors for solar cells.

Vickers Indentation Cracking of Ion-Exchanged Glasses: Quasi-Static vs. Dynamic Contact

The indentation deformation and cracking responses of ion-exchanged glasses were measured using quasi-static and dynamic loading cycles. Two glass types were compared, a normal glass that deforms to a large extent by a shearing mechanism and a damage resistant glass that comparatively deforms with less shear and more densification. The quasi-static indentation cracking threshold for median/radial cracks for the ion-exchanged normal glass was determined to be 7 kilograms force (kgf), while the ion-exchanged damage resistant glass required loads exceeding 30 kgf. The increased cracking threshold of the damage resistant glass composition is attributed to the deformation mechanism, i.e. deformation with greater densification/less shear results in less subsurface damage and less residual stress. Both glass types were also subjected to dynamic indentation where the contact event time was more than 10,000 times shorter than the quasi-static condition. Under dynamic loading conditions, the cracking thresholds of the ion-exchanged normal and damage resistant glasses increased to greater than 50 kgf and greater than 150 kgf, respectively. The stress induced optical retardation was compared for quasi-static and dynamic indents made at sub-cracking threshold loads for both glasses. For indents made at the same sub-cracking threshold load in the normal glass, optical retardation mapping indicates less residual stress surrounding dynamic indents when compared to quasi-static indents. This suggests a rate dependence on the deformation mechanism in normal glasses with higher rates promoting densification in favor of shear. However, for damage resistant glass, the stress induced optical retardation is the same for indents made at both quasi-static and dynamic indentation rates.

Non-destructive stress measurement in double ion-exchanged glass using optical guided-waves and scattered light

Non-destructive stress measurement in double ion-exchanged glass using optical guided-waves and scattered light

The fabrication and gas sensing application of a fast-responding m-CP-PVP composite film/potassium ion-exchanged glass optical waveguide

A simply designed sensor was able to measure trimethylamine (TMA) gas down to a concentration of 0.1 ppb at room temperature, and its response and recovery times were 1.4 s and 5.6 s, respectively.

Effect of Al2O3 content on the mechanical and interdiffusional properties of ion-exchanged Na-aluminosilicate glasses

The effect of the variation in the Al2O3 content on select physical properties of pristine and ion-exchanged glasses in the systems: (75−x)SiO2mol%-25Na2O-xAl2O3 and (75−x)SiO2-15Na2O-10CaO-xAl2O3, are reported. The surface compressive stress, surface hardness and K+/Na+ exchange ratio increase, while the depth of the interdiffusion distance decreases, with increasing Al2O3 content. These trends are shown to be consistent with the compositional variation of the glass transition temperature and the molar volume, and their atomistic and thermodynamic bases are discussed.

Effects of HF etching on nanoindentation response of ion-exchanged aluminosilicate float glass on air and tin sides

The effects of hydrofluoric (HF) acid etching on the surface mechanical properties of the air and tin sides of an ion-exchanged aluminosilicate float glass are investigated. The hardness and Young’s modulus are experimentally measured using nanoindentation. These parameters increase to maximum values at the first 1 min of HF etching before they decrease. Higher values for hardness and Young’s modulus are observed at the tin side than at the air side. Changes in the compressive stress, surface structure, and potassium ion concentration with corrosion time are determined to interpret the variation in the surface mechanical properties. The results would be useful in guiding the etching and strengthening process of ion-exchanged float glass.

Hybrid integrated optical waveguides in glass for enhanced visible photoluminescence of nanoemitters.

Integrated optical devices able to control light-matter interactions on the nanoscale have attracted the attention of the scientific community in recent years. However, most of these devices are based on silicon waveguides, limiting their use for telecommunication wavelengths. In this contribution, we propose an integrated device that operates with light in the visible spectrum. The proposed device is a hybrid structure consisting of a high-refractive-index layer placed on top of an ion-exchanged glass waveguide. We demonstrate that this hybrid structure serves as an efficient light coupler for the excitation of nanoemitters. The numerical and experimental results show that the device can enhance the electromagnetic field confinement up to 11 times, allowing a higher photoluminescence signal from nanocrystals placed on its surface. The designed device opens new perspectives in the generation of new optical devices suitable for quantum information or for optical sensing.

Influence of Acid Etching on Wettability of Ion-exchanged Aluminosilicate Float Glass

Influence of Acid Etching on Wettability of Ion-exchanged Aluminosilicate Float Glass