Silicate Glasses Research Articles

UVC Up-Conversion and Vis-NIR Luminescence Examined in SrO-CaO-MgO-SiO2 Glasses Doped with Pr3.

The application of ultraviolet-C light in the field of surface treatment or photodynamic therapy is highly prospective. In this regard, the stable fluorescent silicate SrO-CaO-MgO-SiO2-Pr2O3 glasses able to effectively convert visible excitation on the ultraviolet praseodymium emission were fabricated and examined. An unusual wide-range visible-to-UVC up-conversion within 240-410 nm has been achieved in Pr3+-doped glasses, revealing their potential advantage in different sophisticated disinfection technologies. The integrated emission intensity was studied as a function of light excitation power to assess a mechanism attributed to UVC luminescence. Especially, it was revealed that the multicomponent silicate glass qualities and praseodymium 3PJ excited state peculiarities are favorable to obtaining useful broadband ultraviolet up-converted luminescence. The glass dispersion qualities were determined between 450-2300 nm. The impact of praseodymium concentration on Vis-NIR spectroscopic glass qualities was evaluated employing absorption spectra, emission spectra, and decay curves of luminescence associated with two involved praseodymium excited states. Especially, efficient interionic interactions can be inferred by investigating the decrease in 1D2 state experimental lifetime in the heavily doped samples. Examination of absorption spectra as a function of temperature implied that excitation at 445 nm should be quite effective up to T = 625 K. Contrary to this, temperature elevation gives rise to a moderate lowering of the visible praseodymium luminescence.

Determination of Crack Resistance of the Cover and Slide Glass by Indentation Method with the Visualization Using Atomic Force Microscopy

Crack resistance of two types of glass was studied – cover glass (0.17 mm thick) and slide glass (2 mm thick) using an improved technique through the use of the probe methods, which makes it possible to increase the accuracy of determining the crack resistance of glass. Colorless silicate glass was used. Crack resistance was determined by the Vickers pyramid indentation method. Microstructure of glasses surface and deformation region after indentation were studied using an atomic force microscope. Mechanical properties of glasses were determined by nanoindentation. Surface relief of a glass slide is rougher than that one of a cover glass. Roughness Rz for a cover glass is less than for a slide glass. Specific surface energy value of 0.26 N/m is higher for the slide glass compared to the coverslip. One elastic modulus value E of the cover glass is 48 GPa, and that one of the slide glass is 58 GPa. The microhardness value H is almost the same for by the glasses and amounts to 6.7 GPa for a slide glass and 6.4 GPa for a cover glass. Atomic force microscope images of deformation region after indentation with a Vickers pyramid show that the first cracks appear at a load of 1 N on the slide glass, and at 2 N on the cover glass. At a load of 3 N, the cover glass is destroyed. Based on the results of crack resistance calculations it was found that critical stress intensity coefficient KIC values are 1.42 MPa∙m1/2 for a glass slide, and 1.10 MPa∙m1/2 for a cover glass.

Influence of PbO/CuO ratio on phase composition, microstructure, melt wettability and recyclability of copper slag

An estimated 30 % (∼11 million metric tons/year) of copper slag is still landfilled globally. Fayalitic copper slags are well-characterized, and they can be recycled into multiple safe end-products. Conversely, the major type of copper slag produced in Europe is lead-rich and warrants a deep understanding of phases present in it, properties, adverse environmental implications, and potential recycling strategies. The objective of this study is to thoroughly investigate such industrial slags by XRF, XRD, Mössbauer spectroscopy, SEM-EDS, novel automated image analysis using Aphelion, hot stage microscopy (HSM) and assess prospects for their valorization. These industrial slags were found to contain 26.1–50.5 wt% PbO, 3.4–5.4 % As2O5 (both hazardous solid wastes), 5.7–42 % CuO (present partly as Cu2O, an irritant), 3.2–18.2 % Fe2O3, 14–15.9 % SiO2 and oxides of chromium, cobalt (both carcinogenic), zinc and nickel (both toxic to aquatic life). The limitation of Rietveld XRD for glass quantification was overcome by newly-developed automated SEM-image processing which revealed that all three slags consisted of a lead silicate glass (36.3–65.8 vol%). Strikingly, rarely published arsenic- and lead-based compounds like (Ca,Pb)4As2O9-x, (Ca,Cu)2PbO4-x and Pb3Ca2Si3O11 were found when slag's PbO/CuO was 0.6, and Ca3As2O8-Pb2SiO4 formed when PbO/CuO equaled 9. The challenge of toxicity and landfilling can be overcome as these slags have high potential to be used for recovery of copper, cobalt, and lead. Radioactive waste immobilization glasses, gamma-ray shielding concrete and glass-ceramic consumer products may also be prepared from them. HSM revealed that a higher PbO/CuO ratio results in lower melting point and smaller melt contact angle indicating such slag can be useful for manufacturing recycled ceramics but corrosive towards refractories in copper converter.

An autonomous self-healing mechanism to improve the chemical durability vs. moisture of PVDF-based gel electrolytes for lithium-ion batteries

Lithium-ion batteries (LIBs) are at the forefront of electrochemical energy storage both for consumer electronics, and for power/energy more demanding applications, such as in automotive and grid levelling. However, their chemical and electrochemical stability must be further improved. Among the instability causes, a major role is played by residual moisture. As a matter of fact, hydrofluoric acid generated by hydrolysis of LiPF6, the most common lithium salt in LIBs, causes safety issues and performance losses. Here we demonstrate the scavenging properties vs. HF of a barium silicate glass used as a filler in a PVDF-HFP based gel polymer electrolyte. A full LiTi2(PO4)3|electrolyte|LiMn2O4 cell is stable for 200 cycles at 0.1C.

Broadband near-infrared emission in barium gallo-germanate glasses co-doped with bismuth, chromium and erbium ions

This work presents barium gallo-germanate glasses co-doped with Bi+/Er3+ and Cr3+/Er3+ ions for NIR luminescence. The addition of Al2O3 content in the glass matrix made it possible to obtain luminescence corresponding to the 3P1→3P0 transition of Bi+ ions. Co-doping with the Bi+/Er3+ system resulted in a broad luminescence spectrum of 1.0-1.6 µm and Cr3+/Er3+ co-doping in selected glass matrix resulted in luminescence in 0.9-1.6 µm band. However, the luminescence of the Cr3+ ions is much lower than that of Er3+ ions. Full Text: PDF References T. Suzuki, G.S. Murugan, and Y. Ohishi, 'Optical properties of transparent Li2O-Ga2O3-SiO2 glass-ceramics embedding Ni-doped nanocrystals', Appl. Phys. Lett., 86(13), 131903 (2005). CrossRef N.V. Golubev et al., 'Pre-crystallization heat treatment and infrared luminescence enhancement in Ni2+-doped transparent glass-ceramics', J. Non-Cryst. Solids, 515, 42 (2019) CrossRef Z. Xu, W. Feng, T. Chen, X. Liu, and J. Qiu, 'Tuning optical properties in PbSe quantum dot-doped borosilicate glass fiber by modulation of network topology', Opt. Laser Technol., 158, 108910 (2023). CrossRef M.A. Hughes, T. Suzuki, and Y. Ohishi, 'Spectroscopy of bismuth-doped lead-aluminum-germanate glass and yttrium-aluminum-silicate glass', J. Non-Cryst. Solids, 356(44), 2302 (2010). CrossRef J. Song, Z. Zhou, B. Zhong, M. Zhang, J. Huang, and L. Han, 'Ultra-broadband near-infrared Cr3+-doped multi-phase glass-ceramics realized by the selective enrichment strategy for near-infrared spectroscopy applications', J. Alloys Compd., 968, 172126 (2023). CrossRef M.A.U. Martines, M.R. Davolos, M.J. Júnior, D.F. de Souza, and L.A.O. Nunes, 'Cr3+ and Cr4+ luminescence in glass ceramic silica', J. Lumin., 128(11), 1787 (2008). CrossRef S. Zhou, H. Dong, H. Zeng, J. Hao, J. Chen, and J. Qiu, 'Infrared luminescence and amplification properties of Bi-doped GeO2−Ga2O3−Al2O3 glasses', J. Appl. Phys., 103(10), 103532 (2008). CrossRef T. Suzuki and Y. Ohishi, 'Ultrabroadband near-infrared emission from Bi-doped Li2O-Al2O3-SiO2 glass', Appl. Phys. Lett., 88(19), 191912 (2006). CrossRef T. Minh Hau et al., 'Super broadband near-infrared emission and energy transfer in Bi-Er co-doped lanthanum aluminosilicate glasses', Opt. Mater., 35(3), 487 (2013). CrossRef H.K. Dan et al., 'Effects of Y3+on the enhancement NIR emission of Bi+-Er3+ co-doped in transparent silicate glass-ceramics for Erbium-doped fiber amplifier (EDFA)', J. Lumin., 219, 116942 (2020). CrossRef E.M. Dianov, 'Bismuth-doped optical fibers: a challenging active medium for near-IR lasers and optical amplifiers', Light Sci. Appl., 1(5) (2012). CrossRef L. Wang, L. Tan, Y. Yue, M. Peng, and J. Qiu, 'Efficient Enhancement of Bismuth NIR Luminescence by Aluminum and Its Mechanism in Bismuth‐Doped Germanate Laser Glass', J. Am. Ceram. Soc., 99(6), 2071 (2016). CrossRef Z. Jiang et al., 'Effects of Al2O3 composition on the near-infrared emission in Bi-doped and Yb-Bi-codoped silicate glasses for broadband optical amplification', J. Non-Cryst. Solids, 383, 196 (2014). CrossRef

Comparison of Two Body Wear Resistance of Novel Strength- Gradient Monolithic Zirconia with Two Different CAD/CAM Materials

Objective: Novel strength-gradient monolithic zirconia is a developed material recently introduced to the market and its mechanical properties should be investigated in vitro. The aim of the study is to compare the wear rates of three different CAD/CAM materials with a chewing simulator after one year of dynamic loading.
 Methods: 7x7x3 mm discs were prepared from lithium disilicate, strength-gradient monolithic zirconia, and zirconia-reinforced lithium silicate glass ceramic. Both groups were divided into two subgroups (n=12) as glazed and mechanically polished. 
 The samples were scanned with a laser scanner device (SD Mechatronic Laser Scanner LAS-20, Westerham, Germany) to determine the amount of wear. The samples were placed in a chewing simulator (SD Mechatronic Chewing Simulator CS-4.2, Westerham, Germany) for 240 000 cycles which is equivalent to 1 year of clinical use. After the dynamic loading in the chewing simulator, the samples were scanned again in the laser scanner, and the data was obtained. Kruskal Wallis test was used to analyze the data.
 Results: The amount of wear of each material was found to be statistically significant (p< .05). No significant differences between the polished and glazed groups of Zir and LD were found but glazed CD was significantly more wear-resistant than polished CD (p< .05). 
 Conclusions: Wear is a phenomenon that can be affected by different factors such as microstructure and surface finishing of the materials. Wear resistance should be taken into consideration when choosing a material.

Unveiling the synergistic effect of Cd doping on structural, optical, mechanical, and γ-ray shielding characteristics of zinc lead silicate glass

Using the traditional melt quenching process, the glass series of xCdO-(5-x) ZnO-35Pb3O4-60SiO2, where x = 1–5 mol%, were created. The X-ray diffraction method was utilized to investigate the non-crystallinity of the glasses that were created. The densities of the fabricated glasses increased from 5.91 to 6.655 g/cm³. Electronegativity (ΔX), bond density (nb), and field strength (F) were calculated. ΔX decreased while nb and F increased with the supply of Cd ions. The optical characteristics Eg, n, αo, εr, χ(3), n2, M, T and more have been investigated. We found that a change in cadmium concentration in the fabricated system influenced all the optical parameters. The mechanical properties, including elastic moduli, have been investigated alongside ultrasonic velocity measurements. The experimental results demonstrated a strong dependence of calculated parameters on increasing CdO concentration. The observation indicates an increase in the elastic moduli with the increasing CdO concentration. Radiation shielding factors were estimated using EpiXS program. μL, HVL, MFP, Zeff, Neff, EBF and EABF for gamma energy between 15 and 15,000 KeV have been investigated. The results indicate that these parameters are affected by the introduction of CdO content into the glass network. The sample ZPSCd5 exhibits the highest radiation shielding parameters among the studied glass samples.

Effects of cerium oxide and cerium sulfate on the optical behavior of synthesized garnet glass ceramics

In this study, the YAG silicate glasses containing the cerium sulfate and cerium oxide salts (17YO3-33Al2O3-40SiO2-2AlF3-3NaF-2CeO2-3B2O3), separately were produced by melting method and glass ceramics were produced by heat treatment of base glasses. According to Photo Luminescence spectrums of both glasses there were emissions in the range of 466 and 435 nm wavelengths related to cerium ions. It was shown that by heating treatment, garnet crystal (in sulfated sample) formed less than the sample with cerium oxide. The emission spectra of both glass-ceramics, when excited at 240 nm, fall within the wavelength range of 460 nm. Also, the 534 and 660 nm emissions wavelengths were obtained by 340 nm wavelength excitation. Heat treatments were done by oxide atmosphere in tubular furnace (single step), SPS sintered powder and in hydrogen atmosphere (by two steps heating). According to XRD results the 24 hrs. heat treating time and the 1060 °C temperature affect the entry of cerium into the garnet structure. Finally, by comparing the spectroscopic results the optical response of the garnet glass-ceramic synthesized in the hydrogen atmosphere was obtained at 400 nm wavelength that indicated this garnet can be applied in the LED industry.

Preparation of some selective glass–ceramics from nano-silica within the Li2O–SiO2 system with ZrO2 for future dental applications

Many recent studies have indicated that some modified silicate glass–ceramics are considered and recommended to be part of the process of dental applications. Examples from the recommended glass–ceramics include modified lithium silicate with various dopants (ZrO2, CeO2), mica-based glass–ceramics, and leucite-based glass–ceramics. The present study employs a new direction of research in the preparation of modified lithium silicate glasses containing varying dopant percents of ZrO2 to produce the parent glasses using nano-silica as an essential chemical component in comparison with silica. The ZrO2-doped glass–ceramic reveals the crystalline phase of lithium aluminosilicate (Li5AlSi2O8) due to the effect of ZrO2. The modified lithium silicate glasses doped with ZrO2 prepared from nano silica indicate their high mechanical properties and can be primarily recommended for dental applications.

Synthesis and Optical Properties of Erbium-Doped Sodium Silicate in Sol-Gel Matrix

In this study, we investigated how the concentration of erbium (0.0, 1, 2 mol% Er) affects the structural and optical properties of thin films made from sol-gel sodium silicate doped with erbium nitrate, thermally treated at 250 °C. Through systematic investigation, we explore the structural evolution and optical behavior of the thin films across varying Er3+ concentrations. The sol-gel demonstrated effective capabilities for substantial concentrations of Er3+ oxides through doping at lower calcination temperatures. The spectroscopic characteristics were studied using visible-near infrared spectroscopy (UV–vis–NIR), transmission electron microscopy, and Fourier transform infrared spectroscopy. Increasing the Er ratio decreased both the transmission and the energy band gap (3.6–3.34 eV) of the films while the absorption peak increased. The obtained results suggest that Er3+ activators demonstrate advantageous optical properties in the evaluated sodium silicate glass matrix. With the introduction of Er, optical transmittance ranges from 85 to 55% in the visible and near-infrared (NIR) regions, highlighting their advantageous characteristics. This research contributes to advancing the understanding of erbium-doped thin films for potential applications in optoelectronic devices and photonics.

Unveiling crystallization and relaxation dynamics interplay in a deeply supercooled glass

Crystallization in glasses below their transition range (Tg) is crucial for understanding material stability and performance. However, data on the time evolution of crystallized fractions in this temperature range is scarce. This study investigates the interplay between structural relaxation and crystallization kinetics in a model silicate glass (5BaO·8SiO2) below Tg. Analyzing the number of crystals, their size, and the crystallized volume as a function of the treatment time, we demonstrate that a single parameter accounting for structural relaxation effectively describes these three crystallization processes. Notably, we found that glasses prone to rapid crystallization below Tg can fully crystallize before reaching complete structural relaxation. These findings highlight the complex interplay between relaxation dynamics and crystallization in deeply supercooled glasses, with implications for understanding and controlling these processes in various materials.

Thermogravimetric and temperature-dependent electrical investigations of Pr3+ doped multi-component silicate glasses for microelectronic technology

Multi-component silicate glasses doped with 0, 0.5, 1, and 1.5 mol% of praseodymium (Pr3+) were synthesized by the sol–gel method. Thermal analysis of the glasses, evinced a high working temperature of 351 °C and Hruby coefficient, K H = 1.415 in the highly doped system, corroborating the effective role of Pr3+ ions in endowing superior thermal stability to the glass. Broadband dielectric spectroscopy was applied to study the temperature-dependent electrical behavior of the glasses for their suitability as electrodes and solid electrolyte materials in batteries. A high dielectric constant of 4797 was evidenced at 1 kHz when recorded at 473 K. The AC conductivity of the glass doped with 1 mol% was observed to be the highest with 94.8 × 10−5 S cm−1 at 10 MHz and 473 K. Jonscher’s power law exponent decreased with temperature, attributing the conducting mechanism to the Correlated Barrier Hopping (CBH) model. The Nyquist impedance spectra demonstrated a depressed semicircle with a spur at the low-frequency end, validating the non-Debye relaxation in the glasses. The equivalent circuitry of the plot predicted parallel combinations of resistor and constant phase elements which reflects a Warburg diffusion and capacitive approach. Bode’s phasor diagram confirmed the capacitive nature by a phase angle of −90° in all the glasses. While a uniform increase in dielectric constant and conductivity was observed up to 1 mol% of Pr3+, a sharp decline in the electrical phenomenon was observed with 1.5 mol% of Pr3+, due to the possible blockade of the hopping of charge carriers by the largely quantified dopant ions. Extracting a high dielectric constant, and ionic conductivity at high frequencies, with an optimal dopant concentration of 1 mol% Pr3+, the composite glasses could be considered for their potential use in integrated microcomponent storage devices as cathode and solid electrolyte materials.

Comprehensive Study on the Physical, Structural, and Optical Characteristics of Cadmium-Doped Bismuth Silicate Glasses

Comprehensive Study on the Physical, Structural, and Optical Characteristics of Cadmium-Doped Bismuth Silicate Glasses

Optical Applications of Europium Ion Doped Silicate Glasses: W-LED

Optical Applications of Europium Ion Doped Silicate Glasses: W-LED

Dissolution behavior of chromite mineral impurities in raw materials of glass production using scanning electron microscopy-energy dispersive spectrometer, X-ray fluorescence spectroscopy and Raman spectroscopy methods

Silica sand is an essential raw material for glass production. The specification of silica sand for each type of glass is the most important point, such as chemical purity, grain size, grain shape, and their impurities. Some of the impurities in the sand can be eliminated by processing yet some cannot be avoided. This paper indicates that as an impurity in the sand, chromite minerals dissolve in glass. 0.200 mm and 0.250 mm grain size chromite minerals were observed grain size change at 1350 °C − 1400 °C − 1450 °C. With increasing in temperature, the rate of size change in the grain diameter increased. Because of the chemical composition of chromite mineral, with increasing temperature, first of all, aluminum and magnesium content start to dissolve in soda lime silicate glass. Then, chromium content transforms into chromium oxide. The transformation rate depends on the mineral composition as well as the temperature and the residence time in the furnace. This paper concerns the chemical composition of the chromite by scanning electron microscopy equipped with energy dispersive spectrometer, the compositions of the raw material analyzed with X-ray fluorescence spectroscopy, inductively coupled plasma optical emission spectrometer and chromite characteristics analyzed by Raman Spectroscopy methods.

Mechanisms and energetics of calcium aluminosilicate glass dissolution through ab initio molecular dynamics-metadynamics simulations

The dissolution of silicate glasses has implications in diverse fields ranging from the immobilization of radioactive waste to the development of sustainable alternatives to Portland cement. Here, we used ab initio molecular dynamics simulations biased with well-tempered metadynamics to study Si-O-T bridge dissociation in calcium aluminosilicate glasses, crucial for understanding their dissolution. In a departure from the conventional Michalske-Freiman model, our findings reveal a nucleophilic substitution reaction mechanism characterized by a short-lived, 5-fold coordinated Si intermediate or transition state, depending on the Si bridge coordination, with a near-trigonal bipyramidal geometry. We find that the reorganization required for reaching this state causes the activation energy barriers to be dependent on the Si bridge coordination, with Si Q3 species serving as the rate-limiting step in the dissolution reaction. Our findings not only challenge long-standing theoretical models but also pave the way for more accurate and comprehensive frameworks for understanding the dissolution of silicate glasses in various applications.

Characterization of the Pb Coordination Environment and Its Connectivity in Lead Silicate Glasses: Results from 2D 207Pb NMR Spectroscopy.

The Pb-O coordination environment in binary (PbO)x(SiO2)100-x glasses with 30 ≤ x ≤ 70 is probed by using two-dimensional 207Pb nuclear magnetic resonance (NMR) isotropic-anisotropic correlation spectroscopy. The isotropic 207Pb NMR spectra show little composition-dependent evolution of the Pb-O nearest-neighbor coordination environment. The systematic variation of the chemical shift tensor parameters offers a unique insight into their local site symmetry and suggests the presence of pyramidal PbO3 and PbO4 sites with sterically active electron lone pairs and with Pb-O bond lengths ranging between 0.23 and 0.25 nm. The PbO3/PbO4 ratio shows a small but monotonic increase from ∼70:30 to 80:20 as the PbO content increases from 30 to 70 mol %. When taken together, the isotropic and anisotropic 207Pb NMR spectra suggest that the majority of the PbOn (3 ≤ n ≤ 4) pyramids in these glasses are connected to the SiO4 tetrahedra via Pb-O-Si linkages. A significant fraction of Pb-O-Pb linkages, where the oxygen is linked only to Pb atoms, appears only in glasses with PbO ≥ 60 mol %. These oxygen atoms appear to be corner-shared between the PbOn pyramids in the structure, and no evidence for edge-sharing between these pyramids is observed in this composition range. We hypothesize that a substantial fraction of the constituent PbOn pyramids start to participate in edge-sharing only at higher PbO contents (>70 mol %), which diminishes the glass-forming ability of the network. This work illustrates the potential of isotropic-anisotropic correlation NMR spectroscopy in structural studies involving nuclides with large chemical shift ranges and anisotropy.

Comparative study on the oxidation behavior of Si2BC3N/Ta4HfC5 ceramics at 1000 °C and 1500 °C: Microstructural evolution and kinetics consideration

The oxidation kinetics and oxide scale morphology of the Si2BC3N/Ta4HfC5 ceramics sintered by hot-pressing were explored at 1000 °C and 1500 °C in flowing air. Dense Si2BC3N/Ta4HfC5 ceramic sintered at 1900 °C with fine grain sizes shows the optimal oxidation resistance both at 1000 °C and 1500 °C. When oxidized at 1000 °C, the formation of a porous oxide layer of Ta2O5, Hf6Ta2O17 and HfO2 containing amorphous SiO2 are primarily responsible for the unsatisfying oxidation resistance of the composite. A highly oxidation resistance component like Si2BC3N can promote the oxidation resistance of Ta4HfC5 at 1500 °C, thanks to the formation of a dense and continuous tantalum-hafnium silicate glass. The oxidation kinetic curve at 1500 °C can be described by a parabolic law whilst the oxidation process is controlled by the diffusion rate of oxygen through the oxide layer; however, the oxidation reaction rate governs the oxidation progress at 1000 °C via a linear oxidation kinetics.

Effects of Na/K-Cl Salts on Hydrolysis of Aluminosilicate Glass Using Ab Initio Molecular Dynamics.

The structural and chemical modifications on the surface of pure and alkali-doped aluminosilicate (AS) glasses due to hydrolysis are investigated using ab initio molecular dynamics. The effects of water on the glass network are fully elucidated by analyzing the short- and intermediate-range structural orders embedded in the pair distribution function, bond length and angle distribution, coordination number, and interatomic bonding. A novel concept of total bond order is used to quantify and compare the strength of bonds in hydrated and unhydrated glasses. We show that AS glass is hydrolyzed by water diffusion near the surface and by proton (H+) transfers into the bulk, which increases with time. Hence, a dissolved glass-water interface becomes rich in Si-OH and Al-OH. The alkali ions associated with the nonbridging oxygen accelerate the hydrolysis by facilitating water and H+ diffusion. Al is more impacted by hydrolysis than Si, resulting in greater variation in the Al-O bond order than Si-O. Doping of NaCl and KCl enhances the ionization of water and the hydrolysis of ASs with increased salt concentration. The KCl doping ionizes more water molecules and causes more degradation of the glass network than NaCl. Co-doping of Na and K results in a mixed alkali effect due to complex interatomic bonding from different-sized ions. These exceptionally detailed findings in highly complex glasses with varying salt compositions provide new and unprecedented atomistic insights that can help to understand the hydrolysis and dissolution mechanisms of ASs and other silicate glasses.

Predicting Silicate Glass Geochemistry Using Raman Spectroscopy and Supervised Machine Learning: Partial Least Square Applications to Amorphous Raman Spectra.

Here, Raman spectroscopy is used to develop a univariate partial least squares (PLS) calibration capable of quantifying geochemistry in synthetic and natural silicate glass samples. The calibration yields eight oxide-specific models that allow predictions of silicon dioxide (SiO2), sodium oxide (Na2O), potassium oxide (K2O), calcium oxide (CaO), titanium dioxide (TiO2), aluminum oxide (Al2O3), ferrous oxide (FeOT), and magnesium oxide (MgO) (wt%) in glasses spanning a wide range of compositions, while also providing correlation-coefficient matrices that highlight the importance of specific Raman channels in the regression of a particular oxide. The PLS suite is trained on 48 of the 69 total glasses, and tested against 21 validation samples (i.e., held out of training). Trends in root mean square error of calibration (RMSEC), root mean square error of cross-validation (RMSECV), and root mean square error of prediction (RMSEP) model accuracy metrics are investigated to uncover the efficacy of utilizing multivariate analysis for such Raman data and are contextualized against recently produced strategies. The technique yields an average root mean of calibration (∼2.4 wt%), cross-validation (∼ 2.9 wt%), prediction (∼ 2.6 wt%), and normalized variance (∼ 28%). Raman band positional shifts are also mapped against underlying chemical variations; with major influences arising primarily as a function of overall oxidation state and silica concentration: via ferric cation (Fe3+)/ferrous cation (Fe2+) ratios and SiO2 (wt%). The algorithm is further validated preliminarily against a separate external set of 11 natural basaltic glasses to unravel the limitations of the synthetic models on natural samples, and to determine the suitability of "universal" Raman-model applications in scenarios where prior chemical contextualization of the target sample is possible. This study represents the first time Raman spectra of amorphous silicates have been paired with PLS, offering a foundation for future improvements utilizing these systems.