Glass Constituents Research Articles

Effective Atomic Numbers of Glass Samples

Effective atomic numbers are a term used to understand the interaction of a compound or material with radiation. In particular, this term is often used for materials with complex structures that can be expressed by a single fixed atomic number. If different elements in a material are present in different concentrations, the effective atomic number of the material can be calculated by considering the contribution of each element. This is a useful method to better understand the response of the material to radiation or the effect of radiation within the material. In particular, when radiation passes through or acts on the material, the effective atomic number plays an important role in determining factors such as the material's radiation exposure properties, absorption or scattering. Effective atomic numbers are used in radiation interaction analyses in various fields such as materials science, medicine, geophysics and industry. This concept is used to express in a simpler way the radiation properties of compounds in which different elements are combined. In this study, the effective atomic numbers of magnesium borosilicate glasses were investigated. Such studies are important in the field of materials science and glass technology because the chemical constituents of glass and their interactions play a decisive role in the properties of glass. Magnesium borosilicate glasses are often used in industrial applications. The properties of these glasses depend on the amount of elements they contain and their chemical structure. Effective atomic numbers can be used to understand the specific properties of a material. By determining the effective atomic numbers of the elements contained in the glass, this study aims to provide an important basis for understanding the properties of the material, such as radiation exposure, electrical properties or optical properties.

Advancements in Biomedical Applications of Calcium Phosphate Glass and Glass-Based Devices-A Review.

Calcium phosphate (CaP) glass has recently gained popularity as a promising material for a wide range of biomedical applications. Recent developments have seen CaP glasses moving from a passive implant material to an active degradable material, particularly as a major constituent of bioresorbable photonic devices. This holds great promise in advanced biomedical applications, since the main constituents of CaP glasses are present in the human body. In this review, the progressive advancements in the biomedical applications of calcium phosphate glass-based devices over the past 50 years are discussed. An overview of their role as reinforcing agents and the studies on doping their matrices for ion releasing and drug and gene delivery are reviewed. Recent applications of CaP glass and fibers in soft-tissue engineering and their potential for optical quality bioresorbable devices are then discussed along with the current challenges and potential future directions, emphasizing the promising role of CaP glass in the next generation of biomaterials. Considering their progress and potential in performing several biomedical functionalities over time, CaP glass-based devices hold promise for becoming enabling tools as an implantable, bioresorbable, multifunctional class of devices in future biomedicine.

Dissolution of simulated nuclear waste glass at high surface area to solution volume, high pH and 70 °C: comparison of international simple glass and SON68 glass.

Long-term static dissolution experiments, lasting up to ∼1500 days, were conducted on International Simple Glass (ISG) and SON68 glass under hyperalkaline pH, at 70 °C, and at a very high glass surface area to solution volume ratio. The study compared (1) glass dissolution kinetics, (2) secondary phase formation, and (3) the microstructure of the altered glass and secondary phase interface. Boron release indicated rapid initial dissolution followed by a slowdown mainly due to a significant pH drop. ISG reached a residual rate regime, while SON68 approached this regime near the experiment's end, with both glasses having similar final dissolution rates. Electron microscopy (SEM, TEM, EDS) of the reacted glass surfaces and the alteration products revealed nontronite formation on SON68, while C(A)SH phases and later rhodesite appeared on ISG, in addition to phillipsite-type zeolite formation observed in both experimental series. TEM observations revealed a porous, foam-like surface altered layer (SAL) near the pristine glass. SON68's SAL nanostructure, more complex than ISG's, had two porous zones, hindering water transfer and glass constituent release, in addition to a pH drop reducing silica network hydrolysis. TEM-EDS showed cation exchange and iron depletion in SON68's SAL, leading to nontronite formation. Secondary phases at the SAL-solution interface did not destabilize the SAL, and no alteration resumption was observed due to the pH drop below the threshold necessary for an alteration resumption due to zeolite formation. In conclusion, the combination of alkaline conditions and very high reaction progress does not lead to the dissolution of the glass by a dissolution-reprecipitation mechanism, as typically observed at much lower SA/V ratios. At the relatively mildly alkaline pH reached within the first year of the experiments, the diffusion of cations through the SAL becomes rate-controlling.

A substrate constituent Na-catalyzed growth of carbon nanotubes on glass substrate by atmospheric pressure PECVD

A growth mechanism of carbon nanotubes (CNTs) without any externally added catalyst is reported in this study. Instead of any externally added catalyst, the constituents of the used soda lime glass substrates seem to play the pivotal role in the growth of CNTs. XPS analysis of the synthesized CNTs reveal that among the various constituents of soda lime glass, sodium (Na) emerges as the primary catalyst for initiating CNT growth. The adopted PECVD technique involving an especially designed spiral-shaped fused hollow cathode source for generating the required atmospheric pressure plasma makes such synthesis easily feasible. The important key factors influencing CNT growth include substrate temperature and plasma pre-treatment of the substrate. Plasma pre-treatment of the substrate at an elevated temperature leads to the formation of catalyst nanoparticles on the surface of the substrate. This report features a detailed CNT growth mechanism proposed on the basis of optical emission spectroscopy and XPS analyses. To be precise, this study demonstrates a novel Na-catalysed synthetic approach for achieving uniform CNT growth on glass substrates without using any externally added catalyst, facilitating the preparation of clean CNTs.

Spectroscopy and absolute photoluminescence quantum yield of Eu3-doped zinc-tellurite glasses for solid state lightning applications

Spectroscopic properties of Eu3+-doped tellurite glass composed of 74 TeO2 + 15 ZnO +5 Nb2O5 + 5 TiO2 + 1.0 Eu2O3(mol %) have been investigated. Phonon energy of the host glass constituents that are linked up with the Eu3+ ions have been evaluated from the photoluminescence excitation spectrum which is found to be 760 cm−1. By utilizing the emission spectrum, the Judd-Ofelt (JO) intensity parameters (Ωλ, λ = 2 and 4) are calculated. The obtained JO parameters are utilized for evaluating the emission cross-sections (σ(λp)) of 5D0 → 7FJ (J = 1, 2 and 4) transitions. An intense emission at 613 nm due to the transition5D0 → 7F2is observed upon 465 nm excitation. Among these, the 5D0 → 7F2 (613 nm) transition has been exhibited the highest (σ(λp)) value and it found to be 2.11 × 10−22 cm2. For the 5D0 level, quantum efficiency (η) is corroborated theoretically as 58.4% and it is in line with absolute quantum yield of 56.7% obtained by Integrating sphere method. The results of Eu3+-doped TZNTEu1.0 glass are significant for the development of solid-state lighting devices at around 613 nm under the excitation of 465 nm.

Based on the CART Decision Tree Model of Prediction and Classification of Ancient Glass-Related Properties

Weathering occurs when glass interacts with the atmosphere. Ancient glass is susceptible to the influence of the burial environment. In the process of glass weathering, its composition ratio will be changed due to a large number of internal elements and environmental elements exchange. In this paper, Fisher's exact test and frequency analysis are used to test the glass pattern, type, color, and surface weathering respectively, and the conclusion is that there are significant differences between glass type and surface weathering, while there are no significant differences between pattern, color, and surface weathering. Then, the CART decision tree algorithm was used to classify the glass into weathered and unweathered, and a binary tree was established with 14 chemical components as characteristics. The average chemical composition of all the sampling points in the sibling nodes of the node where the weathering point is located was used as the predictive value of the chemical composition before the weathering point. Finally, the correlation analysis of the chemical constituents of high potassium glass and lead barium glass was carried out by hierarchical clustering method. In a high-potassium glass, silica is one category, and other chemical components are another category. In a lead-barium glass, silica and lead oxide are one category, and other chemical components are another category. Therefore, it can be considered that the chemical composition relationship of lead-barium glass is more complex.

Improved toxic and radioactive elements immobilization in tin slag-blended lithium aluminate borate glass

Ever-increasing production of tin slag (TS) by various tin smelting industries in Malaysia remains a major environmental concern, wherein a large amount of naturally occurring radioactive materials (NORM) as wastes are dumped annually since 1982 due to the rare earth elements extraction-related activities. Based on this fact, we proposed some tin slag-included lithium aluminate borate (LAB) glass for improved immobilization of both toxic and radioactive elements present in waste using vitrification. These glasses of composition (50–0.5x)Li2O-xAl2O3-(50–0.5x)B2O3 (0.0 ≤ x ≤ 4.0 mol%) blended with 5, 15 and 30 wt% of TS were made by the standard melt-quenching method and characterized to determine their radioactive wastes immobilization potency. The obtained glasses were immersed in deionized water (DW) at 90 °C for up to 28 days to evaluate their durability. The weight loss of the samples was assessed by applying leaching tests. Inductively coupled plasma-optical electron spectra confirmed the ion exchange-mediate interdiffusion leaching of glass, indicating the presence of Li, Al, and Th in contacting water. The pH values of the solutions were increased from 7.00 to 11.93 with the increase in immersion time which was due to the leaching of Li (alkali metal) from the glass. FTIR spectra exhibited distinct absorption bands characteristics to the vibrations of various chemical functional groups like Al–O, B–O–B, BO4, BO3 and O–H stretching, confirming the association between radioactive waste and glass constituents. The observed bands at 850-1750 cm−1 and 3200 cm−1 corresponded to the vibration of the borate network and O–H bonds, indicating the occurrence of a leaching-mediated hydrolysis process. High-purity germanium gamma-ray spectroscopy was used to determine the radioactivity level of radionuclide (Bq g−1) in all samples powder. The radioactivity levels were found to be below the exempted waste limit set by IAEA safety standard for NORM wastes which is 1 Bq g−1 for 232Th and 238U and 10 Bq g−1 for 40K. In other words, the studied LAB glass containing NORM waste is suitable for conventional waste disposal as it is considered an ecologically safe material as other waste. The 90% reduction in radioactivity levels of the LAB glass containing TS compared to the TS itself indicated a successful dilution process of the studied glass, a part of excellent hydrolytic resistance characteristics. Therefore, it is suggested that the proposed LAB glass system in the present study is practical for NORM radioactive waste immobilization.

Influence of Oxidation on Structure, Performance, and Application of Metallic Glasses.

Owing to their unique structure and outstanding properties, metallic glasses are a novel class of structural and functional materials with vast application prospects. However, the metastable amorphous structures and chemical activity of metallic glass constituent elements lead to frequent oxidation during preparation, processing, and application. Comprehensively understanding the oxidation behaviors and underlying mechanisms of metallic glasses is essential for gaining knowledge of metallic glass structures and properties and for promoting engineering applications. Although many studies have examined these issues, more investigations are still required to explore potential industrial applications of metallic glasses. Here, recent research on metallic glass oxidation is consolidated by summarizing the oxidation influence on metallic glass structure, performance, and application and the possibilities and feasibility of oxidizing metallic glasses to reinforce materials or develop material systems are discussed.

Assessment of optical and fluorescence aspects of Er3+-doped multicomponent B2O3 glasses as active media for 1.532 μm near-infrared optical amplifiers

Current work principally provides an idea on controlling the Er3+: NIR (near-infrared) emission characteristics by changing a glass constituent and finding a suitable glass host favorable to design a novel C-optical band (1.53–1.565 μm) amplifier. By melting and rapid quench route, six transparent Er3+ (1 mol%)-doped B2O3-rich glasses having different single and mixed alkali ions were fabricated, and optical and fluorescence (visible and NIR) traits including Er3+ ion upper-levels 4S3/2 and 4I13/2 decay dynamics were inspected for such samples. At 1.4–1.65 μm wavelength range, an intense and wide NIR luminescence band centered at 1.532 μm (Er3+: 4I13/2 → 4I15/2 transition) has been obtained by a 980 nm laser diode pumping (4I15/2 → 4I11/2). NIR fluorescence Δλeff (effective bandwidth) varied depending on added single or mixed alkali ions, and a maximum Δλeff ∼74.66 nm was acquired for Er3+: Li ions constituting glass. For the 4I13/2 → 4I15/2 transition, σemi (stimulated emission cross-section) was evaluated using both Füchtbauer–Ladenburg and McCumber's theories. In all glasses, comparably, higher gain bandwidth (= 5.384 × 10−26 cm3) and peak σemiM (= 1.692 × 10−20 cm2) values have been attained for 4I13/2 → 4I15/2 transition in Li ions containing sample, and also this glass possesses the largest σabs (absorption cross-section) (= 1.459 × 10−20 cm2) for 4I15/2 → 4I13/2 transition. Further, at distinctive P (population inversion) values, gain spectra were computed, and all samples show C-optical band amplification beginning from P = 50%. All analyzed NIR fluorescence results indicate that Li ions having glass could be a potential gain medium for fiber amplifiers.

Exploring the application of blue and red thermoluminescence for dating volcanic glasses

Tephras are significant markers in the stratigraphic record and play a key role in establishing paleoenvironmental and paleoclimate histories worldwide. Despite burgeoning research focused on tephra characterization and correlation techniques, there are still few techniques that allow for the direct dating of tephra, particularly below the lower age limit of K/Ar and Ar/Ar dating methods. In this study, we test different thermoluminescence (TL) dating approaches on the 4–11 μm volcanic glass constituents of three different independently different tephras. By comparing against independent age control, we demonstrate the utility of both blue (320–450 nm) and red (587–651 nm) TL emissions for dating volcanic glasses using single aliquot regenerative (SAR) dose techniques. We find that both blue and red TL emissions from the volcanic glass shards are dim but reproducible and show no evidence for significant sensitivity changes occurring between the natural TL and the first test dose during the SAR protocol. Fading tests on the blue TL signal show that g-values range from 1.6 ± 1.0 to 2.9 ± 1.1%/decade and are statistically indistinguishable with zero at 2σ for the red TL. Bleaching experiments show that both blue and red TL signals are sensitive to light exposure, with sensitivity corrected signals declining by ∼40% over a 2-h period. For all three tephras, both the fading-corrected blue and red SAR-TL ages are consistent with age expectation. These successful results demonstrate the effectiveness of TL techniques for determining the eruption ages of tephra deposits in primary position between ∼1 and at least 30 ka.

Static dissolution experiments under hyperalkaline conditions with dispersed and confined SM539 glass

In the context of the geological disposal of vitrified radioactive waste, cracks are expected at the full scale of the glass blocks. To simulate glass alteration in cracks, static dissolution experiments were conducted with confined SM539 glass powder, at 30 °C in a synthetic young cementitious water. Short and long-term glass dissolution rates were determined and compared with those measured in similar experiments with dispersed glass powder. A long-term rate ~ 10 times lower was found, which might be due to a limited access of the solution to the glass surface area, resulting in a much higher local SA/V and faster increase of local concentrations of leached glass constituents, with possibly a lower local pH. In both types of experiments, the altered glass powder was characterised by XRD and SEM-EDX. Some glass particles showed the presence of an amorphous multi-layer and of fibrous and spherical secondary phases.Graphical abstract

Machine learning guided study of composition-coefficient of thermal expansion relationship in oxide glasses using a sparse dataset

The coefficient of thermal expansion (CTE) is one of the important macroscopic properties of oxide glasses for diversified applications. The optimization of chemical composition is required to produce silicate glasses with desirable CTE for specific applications. The traditional composition optimization approach relies on a trial-and-error laboratory experimentation process which is highly time-consuming. In order to expedite the optimization process, a mathematical model need to be developed that can predict CTE with given oxide glass composition. For this purpose, an ever-increasing interest of worldwide science community have recently been witnessed in data-driven machine learning models. These models have shown interesting as well as encouraging results for many such applications. The present study focuses on building the random forest machine learning regression model for predicting CTE of silicate glasses. The mole fractions of glass constituents (Al2O3, B2O3, Na2O, MgO, CaO, BaO, and SiO2) are considered model input features for predicting CTE. The figures of merit used to evaluate of the model performance are regression coefficient (R2) and mean absolute percentage error (MAPE). The R2 and MAPE of the model are 0.95 and 8.44 respectively in predicting the CTE of unseen glasses, which demonstrate a reasonably good model performance. The model revealed that the mole fraction of Na2O has distinctively high feature importance compared to the rest of the constituents in predicting CTE. The feature importance of mole fractions of glass constituents other than Na2O lies in a narrow range.

Atmospheric Plasma Jet processing for figure error correction of an optical element made from S-BSL7

To meet the increasing market demand for optical components, Plasma Jet Machining (PJM) of Borosilicate Crown Glass (BCG), which can be an alternative to Fused Silica, is presented. Surface figure error correction was performed by applying reactive plasma jet etching, where a fluorine-containing microwave driven plasma jet is employed to reduce the figure error in a deterministic dwell-time controlled dry etching process. However, some of the glass constituents of BCG cause the formation of a residual layer during surface treatment which influences the local material removal. By heating the substrate to about TS = 325 °C to 350 °C during processing, the etching behavior can clearly be improved. Geometric conditions of the optical element nevertheless lead to a characteristic temperature distribution on the substrate surface, which requires an adjustment of the local dwell times in order to obtain the required material removal. Furthermore, the resulting local surface roughness is also influenced by the surface temperature distribution. It is shown that figure error can be significantly reduced by taking the local temperature distribution and resulting local etching rates into account. A subsequent polishing step smoothens roughness features occurring during etching to provide optical surface quality.

Glass Powder Additive on Recycled Polypropylene Filaments: A Sustainable Material in 3D Printing.

This study aimed to characterize the effect of a glass powder additive on recycled polypropylene (rPP) materials from food packaging to be used as filaments in material extrusion (MEX) 3D printing applications. The composite filaments studied were rPP filaments with glass powder (GP) additive in the 2.5%, 5%, and 10% fractions. As a baseline, the filaments made of pure virgin PP and rPP without additive were used. The filament that has been successfully made is then printed into a tensile test specimen and an impact test to observe its mechanical properties. Fourier-transform infrared spectroscopy (FTIR) characterization was also carried out to determine the effect of chemical bonding and thermal characterization using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The results of FTIR characterization on the sample rPP + 10% do not show a typical peak shift of PP, but give rise to new peaks at wavenumbers of 1000 cm−1 (Si-O-Na), 890 cm−1 (Si-H) and 849 cm−1 (O-Si-O), which indicate the typical peaks of the glass constituent compounds. In the thermal characteristics, the addition of GP shows the improved stability of mass changes to heat and increases the melting temperature of rPP. The ultimate tensile strength and Young’s modulus for rPP-based specimens with 10% GP additive showed an increase of 38% and 42% compared to PP specimens. In addition to the improved mechanical strength, the addition of GP also reduces the bending deformation, which can be well controlled, and reduces curvature, which is a problem in semicrystalline polymer-based filaments.

Investigating the Recycling Potential of Glass Based Dye-Sensitized Solar Cells-Melting Experiment.

The effects of climate change are becoming increasingly clear, and the urgency of solving the energy and resource crisis has been recognized by politicians and society. One of the most important solutions is sustainable energy technologies. The problem with the state of the art, however, is that production is energy-intensive and non-recyclable waste remains after the useful life. For monocrystalline photovoltaics, for example, there are recycling processes for glass and aluminum, but these must rather be described as downcycling. The semiconductor material is not recycled at all. Another promising technology for sustainable energy generation is dye-sensitized solar cells (DSSCs). Although efficiency and long-term stability still need to be improved, the technology has high potential to complement the state of the art. DSSCs have comparatively low production costs and can be manufactured without toxic components. In this work, we present the world’ s first experiment to test the recycling potential of non-toxic glass-based DSSCs in a melting test. The glass constituents were analyzed by optical emission spectrometry with inductively coupled plasma (ICP-OES), and the surface was examined by scanning electron microscopy energy dispersive X-ray (SEM-EDX). The glass was melted in a furnace and compared to a standard glass recycling process. The results show that the described DSSCs are suitable for glass recycling and thus can potentially circulate in a circular economy without a downcycling process. However, material properties such as chemical resistance, transparency or viscosity are not investigated in this work and need further research.

Protonation tuned dipolar order mediated 1H→13C cross-polarization for dissolution-dynamic nuclear polarization experiments

A strategy of dipolar order mediated nuclear spin polarization transfer has recently been combined with dissolution-dynamic nuclear polarization (dDNP) and improved by employing optimized shaped radiofrequency pulses and suitable molecular modifications. In the context of dDNP experiments, this offers a promising means of transferring polarization from high-gamma 1H spins to insensitive 13C spins with lower peak power and lower energy compared with state-of-the-art cross-polarization schemes. The role of local molecular groups and the glassing matrix protonation level are both postulated to play a key role in the polarization transfer pathway via an intermediary reservoir of dipolar spin order. To gain appreciation of the mechanisms involved in the dipolar order mediated polarization transfer under dDNP conditions, we investigate herein the influence of the pivotal characteristics of the sample makeup: (i) revising the protonation level for the constituents of the DNP glass; and (ii) utilizing deuterated molecular derivatives. Experimental demonstrations are presented for the case of [1–13C]sodium acetate. We find that the proton sample molarity has a large impact on both the optimal parameters and the performance of the dipolar order mediated cross-polarization sequence, with the 13C signal build-up time drastically shortened in the case of high solvent protonation levels. In the case of a deuterated molecular derivative, we observe that the nearby 2H substituted methyl group is deleterious to the 1H→13C transfer phenomenon (particularly at low levels of sample protonation). Overall, increased solvent protonation makes the dipolar order governed polarization transfer significantly faster and more efficient. This study sheds light on the influential sample formulation traits which govern the dipolar order-controlled transfer of polarization and indicates that the polarization transfer efficiencies of deuterated molecules can be boosted and reach high performances simply by adequate solvent protonation.

Kilowatt power scaling of an intrinsically low Brillouin and thermo-optic Yb-doped silica fiber [Invited

The performance of optical fibers is dependent on both the fiber design and the materials from which it is made. While much of the development over the past few decades has focused on fiber geometry and microstructuring, more recent analyses have shown clear benefits of addressing parasitic nonlinearities at the origins of their light–matter interactions. Reported here are results on intrinsically low Brillouin and thermo-optic core fibers, fabricated using modified chemical vapor deposition. Specifically, fibers in the Yb-doped A l 2 O 3 − P 2 O 5 − B 2 O 3 − S i O 2 system are developed based on how each glass constituent affects the material parameters that enable both stimulated Brillouin scattering (SBS) and transverse mode instability (TMI). One fiber, developed to be very heavily doped, exhibited thermo-optic and Brillouin gain coefficients up to ∼ 3 d B and 6 dB below conventional laser fibers, respectively. A second fiber, designed to approximate a commercial double-clad laser fiber, which necessitated lower doping levels, was output power scaled to over 1 kW with an efficiency over 70% and no observed photodarkening under conventional testing. Design curves for the enabling material properties that drive TMI and SBS also are provided as functions of compositions as a tool for the community to further study and develop intrinsically low-nonlinearity fiber lasers.

Designer Glasses—Future of Photonic Device Platforms

AbstractThe intentional inclusion of key atomic elements in a purpose designed glass helps to achieve unprecedented control over the ultrafast laser written circular waveguide morphology and refractive index change. Behavioral response of glass constituents to ultrafast laser in 14 different commercial silicate glasses having various compositions are studied. Viscosity, aluminum to alkaline earth+alkali ratio, and total silicon content within the glass are the prime control factors for producing waveguides with high circularity and refractive index change. Drawing on this knowledge, the designer glass is successfully fabricated from an empirical formula that facilitates maintaining circular waveguide morphology, high refractive index over fast feed rates, and amorphous composition.

Coating of bioactive glass on magnesium alloys to improve its degradation behavior: Interfacial aspects

The preferable mechanical properties of Mg alloys along with excellent compatibility with human bone have established their applicability as implant biomaterials. However, a higher corrosion/degradation rate of Mg alloys in body fluids limits its biomedical applications. In this direction, surface modification and coating are explored as appropriate strategies to mode the degradation rate of Mg alloys. The constituents of bioactive glass (BG) provide strength, bio-inertness and bone bonding capability. Hence, researchers have explored the coating of BG on Mg alloys and investigated chemical, mechanical and biological properties of the coated alloys. In this review, we have made an attempt to compile the literature works done on the coating of BG on Mg alloys and its features. Underlying interfacial aspects of the coated substrates towards the degradation behavior are highlighted. The way forward to further improve the coating characteristics of BG coated Mg alloys are remarked.

Role of the La/K Compositional Ratio in the Properties of Waveguides Written by Fs-Laser Induced Element Redistribution in Phosphate-Based Glasses.

The local modification of the composition of glasses by high repetition femtosecond laser irradiation is an attractive method for producing photonic devices. Recently, the successful production of waveguides with a refractive index contrast (Δn) above 10−2 by fs-laser writing has been demonstrated in phosphate glasses containing La2O3 and K2O modifiers. This large index contrast has been related to a local enrichment in lanthanum in the light guiding region accompanied by a depletion in potassium. In this work, we have studied the influence of the initial glass composition on the performance of waveguides that are produced by fs-laser induced element redistribution (FLIER) in phosphate-based samples with different La and K concentrations. We have analyzed the contribution to the electronic polarizability of the different glass constituents based on refractive index measurements of the untreated samples, and used it to estimate the expected index contrast caused by the experimentally measured local compositional changes in laser written guiding structures. These estimated values have been compared to experimental ones that are derived from near field images of the guided modes with an excellent agreement. Therefore, we have developed a method to estimate before-hand the expected index contrast in fs-laser written waveguides via FLIER for a given glass composition. The obtained results stress the importance of considering the contribution to the polarizability of all the moving species when computing the expected refractive index changes that are caused by FLIER processes.