Ion-exchanged Silicate Glass Research Articles

Governing Functionality of Silver Ion-Exchanged Photo-Thermo-Refractive Glass Matrix by Small Additives

In this study, the influence of small additives on the spectral and optical properties of Na+–Ag+ ion-exchanged silicate glass is presented. Polyvalent ions, for example, cerium and antimony, are shown to reduce silver ions to atomic state and promote the growth of photoluminescent silver molecular clusters and plasmonic silver nanoparticles. Na+–Ag+ ion-exchanged and heat-treated glasses doped with halogen ions, such as chlorine or bromine, exhibit formation of photo- and thermochromic AgCl or AgBr nanocrystals. Growth of a silver nanoisland film on the glass surface was observed in the case of undoped sample. The presented results highlight the vital role of small additives to control properties of the silver nanostructures in Na+–Ag+ ion-exchanged glasses. Possible applications of Na+–Ag+ ion-exchanged glass ceramics include but are not limited to biochemical sensors based on surface-enhanced Raman scattering phenomena, temperature and overheating sensors, white light-emitting diodes, and spectral converters.

Thermal annealing and laser-induced mechanisms in controlling the size and size-distribution of silver nanoparticles in Ag+-Na+ ion-exchanged silicate glasses

Controlled precipitation of metal nanostructures into glassy matrices have demonstrated to be a valid way to synthesize materials suitable for photonics, optoelectronics and telecom purposes. However, the development of strategies for driving nanostructure formation, and then for tailoring the optical response of the metal doped systems, is still a challenge. Aiming at this, the present study focuses on silver state modification including nucleation/growth of Ag nanoparticles (NPs), manipulation of Ag NPs size and size-distribution in Ag+-Na+ ion exchanged silicate glasses undergone post-exchange treatments, such as thermal annealing and laser irradiation with different irradiation parameters. Raman and optical absorption spectroscopy analyses allow to follow the evolution of the Ag NPs precipitation process starting from the early stages of the overall mechanism, where the glassy matrix is permeated by a dense distribution of Ag0, Ag+ and small aggregates, which are the seeds for the formation of the larger particles upon energetic treatments. In these regards, it is observed that a proper choice of laser irradiation conditions, in terms of wavelength and pulse energy, has a direct impact on the occurrence of the overall clustering process, by specifically promoting Ag ion reduction as well as cluster nucleation, growth and fragmentation. This definitely paves the way to efficient strategies for the realization of optical materials based on controlled distribution of metal clusters with finely tuned structural and optical properties.

Precise residual stress profile in ion-exchanged silicate glass by modified contour method

In this work, the contour method is modified and used to precisely estimate the residual stress profiles in ion-exchanged aluminosilicate glasses, including the effects of non-homogeneous material properties. The method requires the precise measurements of the fracture surface’s topography and exploits fractographic features to mate and accurately determine the out-of-plane deformation after fracture. Residual stresses are computed from the out-of-plane deformation through a weight function approach rather than by numerical methods, as weight functions can easily account for concentration-dependent material properties. The stress profiles in aluminosilicate glass with three different molten salt soaking times were calculated and compared with the approximate profiles measured by optical waveguide. It was found that the optical waveguide’s estimations under-predicts the surface stress by as much as 10–30 %, likely due to the assumption that the stress optic coefficient is unaffected by the K+↔Na+ exchange.

Dendritic structures by glass electrolysis: Studies and SERS capability

We have grown silver dendrites by electrolysis of silver-to-sodium ion-exchanged silicate glass slides. The DC voltage of 150 and 300 V was applied to thin film coplanar electrodes deposited on the slide surface. Exposing the silver structures with weak etchant resulted in some increase in optical absorption and in the essential enhancement of Raman scattering, by the factor of ~106-107. The solid state nature of the glass-dendrite system provided stability of the formed structures, and the prepared SERS substrates did not require special conditions for storage, but a short etching before use.

Thermal annealing and laser induced structural rearrangement and silver state modification in Ag+-Na+ ion-exchanged silicate glasses studied by Raman spectroscopy

The structural modification of the host matrix induced by external treatments in ion-exchanged silicate glasses have not been studied rigorously, despite its importance in tailoring the performances of optical devices. Silicate glass layers prepared by Ag+-Na+ ion-exchange were annealed and irradiated with laser beam. The rearrangement of silica network and Ag clustering process during external treatments in silver-containing glasses were studied by Raman spectroscopy. Modifications of silica network microstructure in ion-exchanged and treated glasses were investigated by analyzing Raman band in between 700 and 1250 cm−1. External treatments result in the sequence of structural changes, which may be interpreted as the change in polymerizing units, appearance and disappearance of non-bridging oxygen centers in glass. The transformation of silver during external treatments was evidenced from the low-frequency Raman spectra. A final assignment of silica-network microstructure modifications due to cluster fragmentation with high energy laser irradiation is attained by using Raman spectral analyses.

Closed-form solution to the residual stresses in ion-exchanged silicate glass including concentration-dependent material properties

In this work, the closed-form solution to the residual stresses in ion-exchanged, silicate glasses accounting for composition-dependent material properties, is derived. The solution is applicable to physical systems where the self-diffusion coefficients of the exchanged, ionic species are nearly identical, such as for Na+ ↔ K+ in both soda-lime and alumino-silicate glass. In the proposed solution, the relaxation function is expressed in terms of the Prony series and the relaxation times, Young's modulus, and the dilation coefficient are assumed as analytic functions of the chemical concentration. A significant, practical aspect of this research is that the derived closed-form solution could be used to establish the relationship between the material properties and the local ion concentration through the regression analysis of experimentally-determined, residual stress profiles. Practical illustrations of how the relationship between the ion concentration and both the dilation coefficient and the relaxation times could be established in ion-exchanged, soda-lime glass are finally presented.

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.

PARAFAC analysis of IBIL spectra from silver ion exchanged glasses

In this work we present for the first time an application of PARAllel FACtor (PARAFAC) analysis to the investigation of Ion Beam Induced Luminescence (IBIL) spectra of Ag+↔Na+ ion exchanged silicate glasses, in order to check the possibility to obtain additional information on the formation of silver aggregates under ion irradiation by a proper statistical rearrangement of experimental spectra. We decomposed the data by PARAFAC taking into account both IBIL emission features and their evolution as a function of the time. Shape and trend under irradiation of the extracted components were correlated to silver concentration and aggregates in the investigated systems. Strength and weakness of this statistical approach applied to IBIL spectra recorded as a function of time were evidenced and discussed.

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.

Ag+↔Na+ ion exchanged silicate glasses for solar cells covering: Down-shifting properties

The suitability of the Ag+↔Na+ ion exchange process was tested for the production of luminescent cover glasses with down-shifting properties suitable for solar cells. The photoluminescence properties were investigated as a function of the preparation parameters (i.e., Ag salt bath concentration, post-synthesis annealing temperature and duration). The performance of the samples was tested by measuring the output power of a Si solar cell covered with the treated glass slides and exposed to a solar simulator radiation; the photoluminescence quantum yield of the best performing samples was also estimated.

Effect of gamma rays absorbed doses and heat treatment on the optical absorption spectra of silver ion-exchanged silicate glass

Samples of a commercial silicate glass have been subjected to ion exchange at 320°C in a molten mixture of AgNO3 and NaNO3 with molar ratio of 1:99 and 5:95 for 60min. The ion exchange process was followed by gamma irradiation in the dose range of 1–250kGy and heating at the temperature of 550°C for different time periods ranging from 10 to 582min. The spectral absorption in UV–Vis range of the Ag–Na ion exchanged glass was measured and used to determine the states of silver prevailing in the glass during the ion exchange, the gamma irradiation and the heat treatment. The gamma irradiation induced holes and electrons in the glass structure leading to the creation of a brown colour, and silver ions trapped electrons to form silver atoms. We observed the first stage of aggregation after irradiation, as well as after heating. The silver atoms diffused and then aggregated to form nanoclusters after heating at 550°C. A characteristic band at about 430nm was induced. The surface Plasmon absorption of silver nanoclusters in the glass indicated that the nanoclusters radius grew between 0.9 and 1.43nm with increasing of annealing time from 10 to 242min and then saturated. We also found that the size of aggregates depends on the value of gamma radiation absorbed dose. Contrary to what was expected, we found that 20kGy is the optimal absorbed dose corresponding to the larger size of the aggregates which decreases for absorbed doses above 20kGy.

In Situ Optical Extinction Measurement for Locally Control of Surface Plasmon Resonance During Nanosecond Laser Irradiation of Silver Ion Exchanged Silicate Glass

Online UV/visible extinction measurement have been achieved during nanosecond Nd:YAG laser irradiation at 532 nm of a silver-exchanged silicate glass after each shot. We have explained the evolution of the integrated spectral evolution with the help of a few observed spots after the laser/glass interaction and completed them by optical and surface measurements. This optical method allows to in situ follow silver ions precipitation in nanoparticles (NPs) and the consequently surface plasmon resonance evolution (SPR). In this study, we focus on the interest of this method for one silver-exchanged soda-lime glass by direct observation of the sample surface. Scanning electron microscopy measurement and optical microscopy were used to identify the various ablation mechanisms. Profilometry was used to evaluate the material distribution and the surface roughness evolution (Rms parameter). Thus, we explain the silver NPs effect on glass matrix at various micrometric scales according to the deposited fluence and silver concentration.

Correction to “Spectroscopic Investigation of Structural Rearrangements in Silver Ion-Exchanged Silicate Glasses”

Correction to “Spectroscopic Investigation of Structural Rearrangements in Silver Ion-Exchanged Silicate Glasses”

Multivariate analysis of Ion Beam Induced Luminescence spectra of irradiated silver ion-exchanged silicate glasses

A multivariate analysis is used for the identification of the spectral features in Ion Beam Induced Luminescence (IBIL) spectra of soda-lime silicate glasses doped with silver by Ag+–Na+ ion exchange. Both Principal Component Analysis and multivariate analysis were used to characterize time-evolving IBIL spectra of Ag-doped glasses, by means of the identification of the number and of the wavelength positions of the main luminescent features and the study of their evolution during irradiation. This method helps to identify the spectral features of the samples spectra, even when partially overlapped or less intense. This analysis procedure does not require additional input such as the number of peaks.

Spectroscopic Investigation of Structural Rearrangements in Silver Ion-Exchanged Silicate Glasses

The silver ion environment and the microstructural rearrangement of Ag+–Na+ ion-exchanged glasses were investigated by means of micro-Raman and photoluminescence spectroscopies. The samples were produced by immersing borosilicate glasses in NaNO3:AgNO3 molten salts baths with different molar ratios of silver nitrate. The modifications of the silica network microstructure were inspected by analysis of the Raman peak at about 1100 cm–1, and the evolution with the silver concentration at the glass surface of the spectral components related to the different silica tetrahedral groups was studied. The formation of silver metal nanoparticles was inferred from the occurrence of the low-frequency Raman peak due to confinement of acoustic vibrations in metal clusters, and their dimensions were evaluated from the position of its maximum. In the light of the structural analyses performed by means of Raman spectroscopy, a final assignment of the different luminescence bands of silver embedded in silicate glasses was a...

Structural Changes of Ag+–Na+ Annealed Ion-Exchanged Silicate Glasses Scanning Electron Microscopy, Far-Infrared Reflectivity, UV-Visible Absorption, and TEM Investigation

The effect of silver ionic exchange on the glass structure in a molten bath at 350 °C was presented in a previous paper Catan et al. [1] (J NonCryst Solids 354:1026–1031, 2008). In this paper, the experiment is driven for a temperature near 310 °C, the eutectic of a 10% AgNO3–NaNO3 molten salt. The various exchanged silicate glasses are further annealed to obtain silver particles in the matrix. Infrared spectroscopy combined with UV/Visible spectroscopy and scanning electron microscopy analysis allowed to correlate the silver-ion penetration and particle formation with the degree of polymerisation of the silicate network. The previous results have demonstrated an insertion of silver ions in the glass structure that is about 10% higher than the departure of sodium ions. Infrared results obtained after ion exchange have proved that local alterations lead to a higher degree of depolymerisation of the silicate network. Here, the annealing of the samples promotes the formation of silver nanoparticles, the infrared measurements prove that the aggregation is correlated to a repolymerisation of the silicate network. Transmission electron microscopy (TEM) is used to evaluate the distribution size of the silver particles after annealing and to correlate it to the evolution of the absorption curves. The TEM observations prove that the particle are below the incident wavelength but shape factor could lead to scattering contribution when particle growths and to absorption spectra evolution.

Silver Structure Environments in Ion-Exchanged Silicate Glasses Studied by X-ray Absorption Fine Structure

X-ray absorption fine structure (XAFS) technique was used to analyze structural geometry of Ag atoms introduced into soda-lime silicate glass and soda aluminosilicate glass by ion-exchange method. The results show that Ag+ ion in soda aluminosilicate glass takes a coordination number of 1.6 with a Ag-O distance of 2.20 A when the ion-exchange ratio x is smaller than 0.47 and of 2.28 A when x is larger than 0.47. The introduced Ag+ ions are stabilized at the non-bridge oxygen (NBO) sites when x is lower than 0.47. The Na+ ions in AlO4 (O4 represents the bridging oxygen) sites are exchanged by Ag+ ions after all Na+ in NBO sites are replaced. The disorder of Ag-O coordination increases gradually with increasing x from 0.24 to 0.47 in soda aluminosilicate glass and increases dramatically when x is larger than 0.47. Ag+ ions takes a coordination number of 1.6 in the ion-exchanged soda-lime silicate glass and of 1.3 after subsequently thermal treatment with the same Ag-O distance of 2.14 A. Debye-Waller factor (DWF) of Ag-O coordination in soda aluminosilicate glass is higher than that in soda-lime silicate glass. Small Ag cluster has a reduced interatomic distance and a larger DWF. Ag nanoparticle in sample Ag-7 is in a state of tensile stress.

Stability of core-shell nanoparticles formed in a dielectric medium

We report the time evolution of declustering phenomenon of metal nanoclusters of size less than 2nm grown in a glassy medium. The clusters are found to be of core shell in structure and the shell formation is inevitable and accompanied by the clusters of such smaller size. Clusters having two different size distributions are grown during the aging period of the sample showing surface plasmon resonant (SPR) absorptions peaked at the wavelengths ∼460 and ∼600nm. We explain the formation of secondary clusters and the cluster decay process based on the SPR of silver clusters formed in an ion-exchanged silicate glass using a generalized Mie scattering theory and a supporting thermodynamic description.

Copper in glazes of Renaissance luster pottery: Nanoparticles, ions, and local environment

Following the recent finding that luster decorations in glazes of historical pottery consist of copper and silver nanoparticles dispersed in a glassy medium, the glaze in-depth composition and distribution of copper nanoparticles, copper ions, and their local environment have been studied in original samples of gold and red luster. The study has been fully carried out by nondestructive techniques such as Rutherford backscattering spectrometry, ultraviolet and visible spectroscopy, x-ray fluorescence, and extended x-ray absorption fine structure (EXAFS). Elemental analyses indicate that gold decorations are characterized by silver and copper, while red decorations by copper only. The color is determined mainly by metal nanoparticles. Specifically, silver nanoparticles determine the gold color, while the red color is determined by nanoparticles of copper. EXAFS measurements, carried out at the Cu K edge, indicate that in both gold and red luster copper is mostly the oxidized form (Cu+ and Cu2+) with a large prevalence of Cu+. States and local environment of copper ions are similar to those found in copper–alkali ion-exchanged silicate glass samples. This strongly supports the view that luster formation is mediated by a copper– and silver–alkali ion exchange as a first step, followed by nucleation and growth of metal nanoparticles.

Molecular dynamics investigations of silver diffusion in glass

Ion-exchanged sodium silicate glasses are studied by means of molecular dynamics computer simulations with empirical potentials. The sodium is partly exchanged by silver. This results in the generation of Ag particles after reduction of the Ag ions and subsequent annealing. The theoretical calculations investigate the modification of the glass structure and especially by the diffusion processes and mechanisms. A quantitative analysis of the diffusion is performed by calculating and interpreting the mean square displacement, as well as the velocity autocorrelation functions. The validity of these results is supported by long time simulations.