Silicophosphate Glasses Research Articles

Exploring the influence of yttrium on the structural, physical, and optical properties of sol-gel synthesized silicophosphate glasses for photonics applications

Yttrium-incorporated silicophosphate glasses hold significant appeal in key sectors such as photonics, optoelectronics, lasers, biomedical applications, and light-emitting diodes (LEDs). In this study, the sol-gel method has been used to prepare the pure and yttrium-doped silicophosphate glasses. The aim of this study is to discover the effect of yttrium doping on the structural, physical, and optical properties of silicophosphate glasses. Various techniques such as X-ray diffraction (XRD), FTIR spectroscopy, and UV–visible analysis have been employed to examine the structural and optical properties of the prepared samples. The XRD analysis confirmed that all the prepared samples exhibited an amorphous nature. Optical measurements conducted indicated that the incorporation of trivalent yttrium ions led to an increase in the refractive index of the prepared samples. Furthermore, a decrease in the energy band-gap values of the samples was observed. The FTIR spectral analysis unveiled the presence of diverse vibration modes in the synthesized samples. These encompassed symmetrical and asymmetrical stretching vibrations of P-O-P linkages, bending vibrations of P-O in PO4 groups, elongation and flexure vibrations of OH groups, and water absorption vibrations of P-O-H in the glasses. The acquired spectra robustly substantiate the function of yttrium oxide as a network modifier within the silicophosphate glass system. The theoretical values of optical basicity (Λth) demonstrated an increase from 0.465 to 0.472, while the values of the interaction parameter (A) exhibited a decrease from 0.218 Å−3 to 0.215 Å−3. Silicophosphate glasses doped with trivalent yttrium ions exhibit significant potential as materials for optoelectronic devices and optical filter systems.

Synthesis, structural, and optical behavior of erbium-doped silicophosphate glasses for photonics applications.

Erbium-incorporated silicophosphate glasses are very desirable in principal sectors such as photonics, optoelectronics, lasers, and illuminating diodes. The focus of the current investigation has been on determining how the erbium dopant affects the optical, physical, and structural characteristics of the silicophosphate-based glasses. The pure silicophosphate glasses and doped with various contents of erbium were prepared by the sol-gel process in this work. The noncrystalline character of the glasses synthesized was confirmed by the XRD patterns that were obtained. The optical measurement showed that the addition of trivalent erbium ions resulted in an increase in the refractive index of the samples and a decrease in their energy band gap values. It demonstrated the presence of P-O-P linkage stretching vibration modes that were both symmetrical and asymmetrical, P-O in PO4 bending vibration modes, OH group elongating and flexure vibrations, and P-O-H water absorption in glasses. The theoretical values of the optical basicity (Ʌth) increased from 0.465 to 0.472, while the values of the interaction parameter (A) decreased from 0.218 to 0.214 . Silicophosphate glasses doped with trivalent erbium ions show promise as optoelectronic and optical filter system materials.

Structure and properties of cerium phosphate and silicophosphate glasses

AbstractWe report on the fabrication, properties, and structure of cerium pyrophosphate glasses and partially substituted cerium silicophosphates. In those glasses, cerium occurs predominantly as Ce(III). A combination of dynamic nuclear magnetic resonance and electrical impedance spectroscopy is used to overcome the problem of assessing cerium speciation. While optical spectroscopy is unable to quantify the ratio of Ce(III)/Ce(IV) due to spectral overlap, proxy observations of the effect of silica‐for‐cerium substitution on optical extinction and the shape and width of the UV band gap corroborate vibrational spectroscopic data of the structural roles of cerium and silica. While silica bonding to phosphate units appears to stabilize Ce(IV), it also impedes the polaron transport, leading to higher polaron activation energy and lower electronic conductivity. On the other hand, Ce(III) is stabilized by coordinating to P = O.

Structural, optical behavior and Judd-Ofelt analysis of europium-doped silicophosphate glasses for red-emitting device applications

Silicophosphate glasses doped with europium are of great interest in fundamental fields such as photonics, luminous diodes, optoelectronics, and lasers. In the present study, we have focused on exploring the effect of the europium (Eu3+) dopant on the structural, physical, and optical properties of silicophosphate glasses. In this study, pure and europium-doped silicophosphate glasses were synthesized by using the sol-gel method. To evaluate the structural and optical properties of the prepared glasses, X-ray diffraction (XRD), Fourier transform infrared (FTIR), UV–visible spectroscopy, photoluminescence spectra, and luminescence decay of trivalent europium ions in glasses were examined. XRD revealed that all of the synthesized glasses contained amorphous phases. FTIR transmittance spectra demonstrated that the addition of europium in the silicophosphate glass leads to a reduction in the dimensionality of the network as a result of the rupture of the Si–O–Si bonds into their structure. The band gap energy of the samples increases with the dopant of europium. The photoluminescence spectrum shows the line characteristics of the Eu (III) ion 5D0→7FJ (J = 0, 1, 2, 3 and 4). Large bands were observed, suggesting non-homogeneous sites that are characteristics of amorphous systems. The intensity parameters ΩJ (J = 2, 4) and the radiative properties of Eu3+ ions in the prepared glasses, such as the stimulated emission cross-section (σe), transition probability (A), radiative lifetime (τcal), and branching ratio (βR) were determined, and Eu3+ emission may be suggested for suitable laser applications due to its high value of βR=52.71%. Furthermore, the CIE 1931 color coordinates of the synthesized glass (x, y) are within the range of (0.63, 0.36) and are quite close to the standard red color (0.67, 0.33), indicating that pure bright red emission has been achieved. The obtained results show that the europium-doped silicophosphate glasses can be appropriate for use as a red laser material.

Synthesis and characterization of silicophosphate glasses doped with europium

In essential sectors such as photonics, luminous diodes, optoelectronics, and lasers, silicophosphate glasses doped with europium are of tremendous interest. In this work, the sol gel method was used to prepare pure and europium-doped silicophosphate glasses. The structural properties of these glasses are examined by XRD and Fourier transforms infrared spectroscopy (FTIR). XRD revealed that all of the prepared glasses contained amorphous phases. FTIR spectroscopy spectra of the samples were recorded in the 500 to 1400 cm−1 spectral range. The structural examinations based on these spectra demonstrate slight decreases in the transmittance bands of the silicophosphate glasses doped with europium, indicating the reduction in the dimensionality of the network because of the breaking of the Si-O-Si bonds into their structure. The findings show that europium oxide has a function in the network that modifies the vitreous matrix structure.

Diffusion of protons and sodium ions in silicophosphate glasses: insight based on first-principles molecular dynamic simulations.

We propose a microscopic diffusion mechanism of protons and Na+ ions in phosphate glasses using first-principles molecular dynamic simulations. Protons hop and are chemisorbed onto non-bridging oxygen (NBO) of nearby PO4 tetrahedra through hydrogen bonds. The subsequent behavior depends on the morphology of the PO4 tetrahedra (QnP values). When a proton is adsorbed onto the NBO of a Q3P unit, it is desorbed on a short time scale of within 10 fs and re-adsorbed onto the NBO that was previously adsorbed. However, when a proton is adsorbed onto the NBO of a Q2P unit, another proton coordinated before adsorption is desorbed in a chain, resulting in the diffusion of protons. When a Na+ ion is present in the vicinity, the adsorption of a proton onto a Q2P unit leads to a decrease in the electrostatic interaction between Na+ and O- ions and induces the diffusion of Na+ ions. We conclude that the difference in the morphology of PO4 tetrahedra greatly affects the diffusion of protons and Na+ ions.

In vitro bioactivity of silicophosphate glasses doped with ZnO, SrO or CuO

Silicophosphate glasses with variable divalent ion dopants (Zn2+, Sr2+ or Cu2+) were prepared via melt annealing route. Parent and doped glasses were thermally heat-treated through a two-step regime to be converted into their glass–ceramic derivatives. Fourier transform infrared (FT-IR) spectral data were recorded for parent glasses and their glass–ceramics derivatives to identify the structural building units which reveal vibrational bands due to both main phosphate and some silicate groups and to verify the bioactivity behavior after immersion in diluted phosphate solution. X-ray diffraction studies indicate the formation of different phosphate and silicate crystalline phases in the derived glass–ceramics which varied with the type of dopant oxide. SEM investigations of the glass–ceramics before and after immersion in phosphate solution showed multicomponent microcrystalline textures in the studied micrographs before immersion. Nodular-shaped microcrystalline features were identified after immersion in phosphate solution referring to the formation of crystalline hydroxyapatite. The undoped glass–ceramic is identified to crystallize in almost equal silicate and phosphate phases, while with the dopant ZnO, SrO or CuO, the crystalline phases are only of phosphates, while the silicate phase is assumed to be retained in the surrounding remaining vitreous boundaries.

Modification of silicophosphate glass composition, structure, and properties via crucible material and melting conditions

AbstractCeramic crucibles are known to corrode in contact with glass melts. Here, we investigate the effect of alumina and fused silica crucibles on the composition, structure, and properties of silicophosphate glasses. Glasses in the system 0.3 Na2O‐0.6 P2O5‐0.1 SiO2 were melted in platinum, alumina, or fused silica crucibles at 900°C or 1200°C for 0.5‐12 hours. Al2O3 and SiO2 were found to leach from the crucibles into the glass melt and alter the glass composition: Al2O3 content increased with melting temperature and time, resulting in up to 10 mol% Al2O3; SiO2 from fused silica crucibles was also introduced into the glass, resulting in a 25% higher SiO2 content compared to the nominal composition. Glass density, transition temperature, thermal expansion, and mechanical properties were strongly affected by these compositional changes. Based on vibrational spectroscopy, this is explained by increasing numbers of P–O–Al or P–O–Si bonds, resulting in a depolymerization of the phosphate network, and ionic cross‐linking by high field strength aluminum or silicon ions. With increasing alumina content, P–O–Si bonds were replaced by P–O–Al bonds. 31P and 27Al MAS NMR spectra revealed that aluminum is present in sixfold coordination exclusively and fully bonded to phosphate species, connecting phosphate groups by P–O–Al–O–P bonds.

Synthesis of lithium superionic conductor by growth of a nanoglass within mesoporous silica SBA-15 template

Nanodimensional silica based glasses containing alkali ions have recently been grown using suitable templates. These have shown electrical properties drastically different from those of their bulk counterpart. We have synthesized silicophosphate glasses having lithium ions with concentrations of 15–35 mole% Li2O within mesoporous silica SBA-15 (Santa Barbara amorphous-15) comprising of pores of diameter ~5 nm. The nanoglasses are characterized by electrical conductivities 5–6 orders of magnitude higher than those of the corresponding bulk glasses. These properties are attributed to the presence of a larger free volume in the nanoglasses as compared to their bulk states. The nanocomposites with 35 mole% Li2O exhibit an electrical conductivity of ~3 10−4 S · cm−1 at around room temperature. The activation energy for Li+ ion migration has been estimated from the conductivity-temperature variation to be 0.078 eV. These nanocomposites are believed to be ideally suited for the fabrication of solid state lithium ion batteries. We have also explored the efficiency of silicophosphate glass powders as possible electrode materials. Glass of composition 70SiO2/30P2O5 was prepared by using Pluronic P-123 tri-block copolymer along with suitable precursor sols. Cyclic voltammetric and galvanostatic charge/discharge measurements were carried out on the samples prepared in combination with suitable conductive fillers using a two-electrode system. These exhibited a high specific capacitance of 356 F g−1 making them ideally suitable as electrode materials for making a lithium ion solid state battery system.

Dissolution Kinetics of Hot Compressed Oxide Glasses.

The chemical durability of oxide glasses is an important property for a wide range of applications and can in some cases be tuned through composition optimization. However, these possibilities are relatively limited because around 3/5 of the atoms in most oxide glasses are oxygens. An alternative approach involves post-treatment of the glass. In this work, we focus on the effect of hot compression on dissolution kinetics because it is known to improve, for example, elastic moduli and hardness, whereas its effect on chemical durability is poorly understood. Specifically, we study the bulk glass dissolution rate of phosphate, silicophosphate, borophosphate, borosilicate, and aluminoborosilicate glasses, which have been compressed at 0.5, 1.0, and 2.0 GPa at the glass transition temperature (Tg). We perform weight loss and supplementary modifier leaching measurements of bulk samples immersed in acid (pH 2) and neutral (pH 7) solutions. Compression generally improves the chemical durability as measured from weight loss, but the effect is highly composition- and pressure-dependent. As such, we show that the dissolution mechanisms depend on the topological changes induced by permanent densification, which in turn are a function of the changes in the number of nonbridging oxygens and the network cross-linking. We also demonstrate a direct relationship between the chemical durability and the number of chemical topological constraints per atom (nc) acting within the molecular network.

AC Conductivity and Dielectric Behavior of Silicophosphate Glass Doped by Nd2O3

Silicophosphate glasses of nominal composition (P2 O 5 50%-SiO2 30%-Na2O 20%) and Nd2 O 3 additive (0.5 and 2 wt%) were prepared and dielectric behavior has been studied over a temperature range (302–483 K) in the frequency range (0.5 - 3243 kHz). Frequency dependence of AC conductivity (σ ac), has been explored using the universal power law. Disparity of the frequency exponent (s) with temperature was examined in terms of diverse conduction mechanisms. The principal conduction mechanisms were found correlated to both barrier hopping (CBH) and quantum mechanical tunneling (QMT) models. Temperature dependence of σ ac (ω) showed a linear increase with different frequencies. In addition, the capacitance, loss tangent, dielectric loss and dielectric constant were calculated over variable temperature ranges and frequencies.

Investigation of the local environment of Eu3+ in a silicophosphate glass using site-selective spectroscopy and Molecular Dynamics simulations

Silicophosphate glasses (SiO2-P2O5) doped with Eu3+ ions were synthesized by the sol-gel process. Optical properties of these glasses were investigated by means of emission spectra and lifetime measurements. The Fluorescence Line Narrowing (FLN) technique was also used to explore the local structure around the Eu3+ ions in this host and to understand the role of phosphate as a codopant. As it is the case for aluminum, the ability of phosphate to avoid the rare earth clustering was investigated, and the role of this codopant in modifying the local order around the rare earth ion was evidenced. The analysis of the FLN spectra and lifetime measurements is consistent with this interpretation. Molecular Dynamics simulations were performed to evaluate and confirm these structural features. Two classes of europium sites were distinguished in agreement with the experimental characterization.

Sol-gel preparation and structural investigations of silico-phosphate glasses doped with Fe ions

Different aspects related to the sol-gel preparation and structural investigation of silico-phosphate glasses (SiO2–P2O5 system) doped with Fe ions are reported. During the preparation process, tetraethoxysilane was used as a precursor for SiO2 and phosphoric acid (H3PO4-HP) for P2O5. Ferric chloride was used as precursor for Fe ions, water as reagent for hydrolysis reaction and ethylic alcohol as solvent. The pH of the sols was modified by adding hydrochloric acid and ammonia. It was observed that a slight increase of the solution temperature (up to 40 °C) allows a drastic decrease of the gelation time (from days to hours). The structure of the obtained powders dried in air at room temperature and at 100 °C for 10 h and subsequently thermally treated at different temperatures was investigated by Fourier transformed infrared (FTIR) and Raman spectroscopy. Vibration modes specific to Si–O–Et, Si–OH, P–O–P, P–O–Si, hydrogen bonds and H2O, as well as combined modes have been observed. The local structure and electron configurations of the doping Fe ions have been investigated by 57Fe Mossbauer spectroscopy. Mossbauer spectra of the sample with molar composition 0.85SiO2 0.08P2O5 0.07Fe2O3 (Fe15) annealed at 300 °C collected at 5.7/6 K, 30 K, 60 K and at room temperature The magnetic pattern is assigned (by its hyperfine parameters) to α-Fe2O3 (36 % from total Fe, the rest being dispersed in the matrix as paramagnetic Fe with octahedral oxygen configuration).

Structural and microstructural studies of zinc-doped glasses from NaCaPO4-SiO2 system

Silico-phosphate glasses and glass-ceramics materials from NaCaPO4-SiO2 system have the ability to form strong chemical bonds with living tissue. Their bioactivity is associated with the rapid formation of a thin layer of hydroxycarbonate apatite (similar to biological apatite) on their surface when the materials are implanted or in contact with biological fluids. The bioactive glasses and glass-ceramics have been applied in bone regeneration field, coating of implants and scaffolds. During implantation there is a risk of adherence and colonization of bacteria on the surface of the implants, which may lead to their failure. Bioactive materials containing additions of antibacterial ions can reduce the number of microbes on implants' surface and kill bacteria or inhibit their growth. The choice of zinc was related to its antibacterial properties and fundamental role in bone formation.Several compositions of zinc doped glasses were synthesized by sol-gel method. Using X-ray, Infrared (IR) and Raman spectroscopy, the structure of amorphous state was characterized. It was proved that addition of zinc ions causes depolymerizing influence on phosphate sub-network and the increase of silicate sub-network polymerization level. The morphology and composition of the glasses was analyzed by scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS). Immiscibility takes place in all obtained glasses. The influence of zinc doping on the bioactivity of the glasses from NaCaPO4-SiO2 system was researched. It was noticed that zinc-doped glasses lack bioactive properties. Moreover thermal analysis was carried out to check the thermal properties of the glasses. It was showed that zinc ions introduction provides one step crystallization – the glasses without Zn2+ has three steps crystallization.

Influence of SiO2 on the Luminous Properties of Nd3+-Doped Barium Silicophosphate Nanostructured Glasses

Barium phosphate glasses with high glass transition temperature, which belong to alkali-free glasses, are valuable candidates for application in high-power laser glasses. With the introduction of SiO2 content, the thermal properties, refractive index, and mechanical properties of these glasses can be improved, while the effects that silica exerts on the structure and luminous properties of the glasses are still in need of further study. Herein, the structure and the luminous properties, containing transmittance and fluorescence properties, of Nd3+-doped barium silicophosphate glasses are studied. It is notable that both the maximum values of luminous intensity and luminous decay time appear at the composition of 26.7 mol% of SiO2, a composition which also possesses the largest ultraviolet end edge redshift. The maximum percentage of bridging oxygen (BO) is also found at this composition, which is quantified by X-ray photoelectron spectroscopy (XPS). And both the luminous intensity and luminous decay time of these glasses appear in positive correlations with the number of bridging oxygen of the glass matrix. Thus, a method to improve the luminous properties of the barium phosphate glasses through changing the local chemistry state of the dopants by introducing SiO2 content is proposed. The optimized composition found in this paper would be useful throughout the wide field of optics.

High Glass Transition Temperature Barium Silicophosphate Glasses Designed with Topological Constraint Theory

Alkali‐free glasses have attracted tremendous attentions for their high glass transition temperature (Tg). Such a feature broadens their potential applications, especially in the area of high‐density and high‐power laser glasses. BaO–P2O5 glasses, as one of the major matrix materials due to its high‐Tg, can be applied in high‐power laser glasses. Introducing SiO2 is an effective method to improve the thermal, refractive index, and mechanical properties of phosphate glasses. Herein, we studied the barium silicophosphate glasses with MAS NMR and the Tg was successfully calculated by the topological constraint theory. The designed glass (20BaO–26.7SiO2–53.3P2O5, mol%) with a high Tg (789K) was prepared and it also exhibited high refractive index and high Vickers hardness, suggesting the barium silicophosphate glasses have widespread applications in high‐power laser glasses and optical fibers.

Structure and microstructure of the glasses from NaCaPO4–SiO2 and NaCaPO4–SiO2–AlPO4 systems

Structure and microstructure of silico-phosphate glasses belong to NaXPO4-SiO2 and NaXPO4-SiO2-AlPO4 (where X = Ca or/and Mg) systems were investigated. Scanning electron microscopic studies combined with EDX were made it possible to show the occurrence of phase separation in the obtained materials. It was found that alumina has a homogenising effect on the microstructure of silico-phosphate glasses. Addition of a small amount of alumina (5 mol. % of AlPO4) causes the chemical compositions inversion of the matrix and the inclusions. Structural investigations of the obtained glasses as well as of the corresponding crystalline materials showed that the studied glasses exhibit domain composition. Structure of the domains is close to that of the corresponding crystalline phases. Spectroscopic investigations involving spectra decomposition into component bands were made it possible to establish the homogenising effect of aluminium on the structure of silicate-phosphate glasses. Presence of alumina leads to elimination of PO bonds as well as replacement of Si–O–P by the Al–O–P ones.

Synthesis and Spectral Properties of Nd2O3-Doped Sodium Silicophosphate Glass

Combined UV-visible and FTIR spectral studies of undoped and Nd2O3 –doped sodium silicophosphate glasses were carried out to characterize the optical and structural properties of such glasses. The base undoped silicophosphate glass exhibits strong UV absorption which is due to the presence of unavoidable trace iron impurities (mainly Fe3+ ions) present contaminated within the raw materials used for the preparation of such glasses. Nd2O3 –doped glasses show characteristic absorption bands extending in the entire visible region which are attributed to the contribution of Nd3+ ions with distinct peaks which are almost constant with the increase of dopant. This comes from the combined compact glass structure containing two glass forming units and the shielding of the rare-earth ions. Infrared absorption spectra of the studied glasses reveal characteristic IR bands due to the combination of both silicate and phosphate groups. The introduction of Nd2O3 within the dopant level (2 %) produces no variations in the IR vibrational bands due to the presence of the two structural silicate and phosphate groups giving compactness of the network structure. The deconvoluted spectra reveal the presence of phosphate groups in a slightly high ratio due to the high content of P2O5 in the composition.

Anneal-induced enhancement of refractive index and hardness of silicophosphate glasses containing six-fold coordinated silicon

A considerable number of optical devices have significantly benefited from the development of phosphate glasses as substrate materials. Introducing silica into sodium phosphate is an effective method to enhance its mechanical and optical properties. Through annealing treatment, the tetrahedral silicon oxide network structure (Si(4)) can be transformed into an octahedral structure (Si(6)) with more constraints. Here, we use high-temperature Raman and Nuclear Magnetic Resonance to reveal the mechanism of transformation between the Si(4) and Si(6) silicon oxide structures. The increase of the Si(6) content results in the phosphate glasses having higher refractive index and hardness. Based on this, the refractive index contribution of SiO6 is obtained.

Tailoring sodium silicophosphate glasses containing SiO₆-octahedra through structural rules and topological principles.

SiO4 tetrahedra in certain sodium silicophosphate glasses can be transformed into SiO6 octahedra that determine the macroscopic properties of silicophosphate glasses to a large extent. In this study, we develop the quantitative evolution rule of each network former. In addition, based on the underlying structure and topology, temperature-dependent topological constrain theory is used to elucidate the composition dependence of glass transition temperature and hardness. The properties of sodium silicophosphate glasses have been accurately predicted. These understandings will help us design new type of silicophosphate glasses containing unique SiO6 octahedra.