Coloration and Nonlinear Optical Properties of ZnTe Quantum Dots in ZnO–TeO2–P2O5 Glasses

ZnO–TeO₂–P₂O₅ glasses were prepared by melt‐quenching method. The color of the glass samples changed from colorless to pale red and dark red with increasing TeO₂ content. Coloration mechanism and nonlinear optical properties of ZnO–TeO₂–P₂O₅ glasses have been investigated. Raman spectra and transmission electron microscope measurements indicated the precipitation of ZnTe quantum dots in the glasses and ZnTe quantum dots are the origin of coloration. Z‐scan technique was used to examine the nonlinear optical properties of the glasses. The glass sample with 30 mol% TeO₂ exhibits large third‐order nonlinear optical susceptibility of 10^?11 esu.     

Effect of CoO and Gamma Irradiation on the Infrared Absorption Spectra of Lithium Borate Glasses

Undoped and cobalt-doped lithium borate glasses (LBG) of various compositions, by varying cobalt contents were prepared by a conventional melt quenching technique. The density and molar volumes of the glass samples were estimated and; infrared absorption spectra were measured in the spectral range 400–1600 cm^?1before and after an irradiation dose of 50 kGy and 200 kGy. Experimental results showed that the density of studied samples increased as CoO increased while the molar volume decreased. FT-IR spectra of the prepared samples have been analyzed by the deconvolution of the spectra. A deconvolution technique is presented to make use of the BO₄ data and follow the change in the modifier and former fractions of CoO. FTIR was also used to study the glass system before and after gamma irradiation. The experimental results clearly indicate that after irradiation a significant change in the structure of the LBG glass network is observed. The modifying action of CoO on the glass composition is also studied. The glasses doped with 5 wt% of CoO are relatively more radiation resistant than the other compositions.     

Structure and physical properties of Ge15Sb20Se65‐xSx glasses

We explored the structure and physical properties of Ge₁₅Sb₂₀Se_65‐xS_x (with x = 0, 16.25, 32.5, 48.75, and 65) glasses in order to screen the best compositions for the applications in photonics, since the laser damage thresholds in Se‐based glasses are too low although their optical nonlinearities are high. We found that, linear and nonlinear refractive index of the glasses decreased, but glass transition temperature T_g, optical bandgap E_g and the laser damage threshold increased with increasing S content. We further employed Raman scattering and high‐resolution X‐ray photoelectron spectra to probe the structure of the glasses. Through the analysis of the evolution of the different structural units in the glasses, it was concluded that, the heteropolar bonds (Ge–Se/S, Sb–Se/S) were dominated in these glasses. With the increase in chalcogen Se/S ratio, the number of the Se‐related chemical bonds (Ge–Se, Sb–Se and Se–Se) increased and that of S‐related chemical bond (Ge–S, Sb–S and S–S) decreased gradually, and Ge was prior to bond with S rather than Se. The elemental substitution thus had negligible effect on the glass structure. The change of the physical properties was mainly due to the difference of the strength of the chemical bonds between S–Ge(Sb) and Se–Ge(Sb).     

High niobium oxide content in germanate glasses: Thermal,structural, and optical properties

Niobium alkali germanate glasses were synthesized by the melt‐quenching technique. The ternary system (90‐x)GeO₂–xNb₂O₅–10K₂O forms homogeneous glasses with x ranging from 0 to 20 mol%. Samples were investigated by DSC and XRD analysis, FTIR and Raman spectroscopy, and optical absorption. Structural and physical features are discussed in terms of Nb₂O₅ content. The niobium content increase in the glass network strongly modifies the thermal, structural and optical properties of alkali germanate glasses. DSC, Raman and FTIR analysis suggest niobium addition promotes NbO₆ groups insertion close to GeO₄ units of the glass network. XRD analysis also pointed out that samples containing high niobium oxide contents exhibit preferential niobium oxide‐rich phase after crystallization after heat treatment, which is similar to orthorhombic Nb₂O₅. Absorption spectra revealed high transmission range between 400 nm to 6.2 μm, added to a considerably decreased hydroxyl group content as the addition of niobium in the alkali germanate network. The niobium oxide‐rich phase crystallization process was studied and activation energy was determined, as well as nucleation and crystal growth temperatures and time for obtaining transparent glass‐ceramics.     

Optical Properties of Silver Halide Photochromic Glasses Doped with Cobalt Oxide

Photochromic glasses having composition (SiO₂)₄₅(B₂ O ₃)₃₅(Al₂O₃)_7.5(Na₂O)_12.5(AgBr), (Cu₂O) doped with (CoO) _x , in which, x = 0, 0.006, 0.02 and 0.07 g were prepared using the conventional melt technique. The amorphous nature of these glass samples was confirmed using X-ray diffraction analysis at room temperature. The absorption measurements in the infrared region of the spectrum were recorded in the wave number range (4000–400) cm^?1. Spectral reflectance and transmittance at normal incidence of the prepared glass samples were recorded with a spectrophotometer in the spectral range 200–2500 nm. Experimental and theoretical densities of the prepared glass samples were measured, calculated and compared. Analytical expressions were used to calculate the real and imaginary parts of the refractive indices. Dispersion parameters such as: single oscillator energy, dispersion energy, average oscillator wavelength, and Abbe’s number were deduced and compared. Absorption dispersion parameters such as: optical energy gap for direct and indirect transitions, Urbach energy and steepness parameter were calculated. Effects of doping with cobalt oxide CoO as a transition metal on linear and predicted nonlinear optical parameters were investigated and interpreted. Experimental results indicate that there is an optimum concentration of cobalt doping around 0.006 g. The optical band gap decreases with increasing doping and causes an increase in nonlinear optical parameters. Doping with cobalt oxide improves the linear and nonlinear optical properties of the prepared glasses.     

Thermal behavior,structure, crystallization and solubility of the melt-derived SiO2–P2O5–Na2O–F-MO (M = Ca,Sr, Zn) glasses

In this work, phospho-silicate glasses with SiO₂–P₂O₅–Na₂O–F-MO (M = Ca, Sr, Zn) composition were prepared by using the conventional melt quenching technology. Structural, physical, and chemical property tests were used to analyze the effects of different SrO and ZnO content on the structure and properties of the glasses. The results showed that the glass stability varied nonlinearly as CaO was replaced by SrO, which was mainly related to the different positions of Sr²⁺ and Ca²⁺ ions breaking the network connection in the network structure, and the substitution of ZnO for CaO led to a continuous decrease in the stability of the glasses. The immersion experiment showed that SrO doping was more feasible than ZnO doping to improve the biological activity of the glasses, and the doping of ZnO promoted the dissolution of ions in the glasses. The obtained results indicated that the glass samples prepared in this paper have potential biological activity, which has potential applications in dental treatment.     

Large third-order optical nonlinearity of ZnO–Bi2O3–B2O3 glass–ceramic containing Bi2ZnB2O7 nanocrystals

Homogeneous transparent optical glass–ceramics precipitated with unique nonlinear crystals are promising materials for photonic applications. We have utilized heat treatment method to prepare transparent ZnO–Bi₂O₃–B₂O₃ glass–ceramic containing Bi₂ZnB₂O₇ nonlinear nanocrystals. A large third-order nonlinear susceptibility χ⁽³⁾ of glass–ceramic is measured by Z-scan technique, which mainly attributed to unique [BiO₆] and [B₂O₅] units in Bi₂ZnB₂O₇ crystal structure and the quantum size effect of nanoparticles. The discovery is of great potential in the application of nonlinear optical integrated devices.     

Synthesis,physical, optical,structural and radiation shielding characterization of borate glasses: A focus on the role of SrO/Al2O3 substitution

In a bid to expand the amount of information available on glass systems and their potential applications for radiation shielding design, glass samples with the compositions (30-x)SrO-xAl₂O₃–68B₂O₃–2V₂O₅(x = 5, 7.5, 10, 12.5&15 mol %) coded as SABV0 - 4 were prepared by the melt-quenching technique and analyzed for their optical, structural, physical, and radiation shielding features. The glassy (amorphous) nature of the SABV glass samples was affirmed by broad peaks of X-ray diffraction spectra. Calculated values of density and molar volume shown opposite behavior and the variation of these values were discussed as structural modifications in the glass matrix. From recorded optical absorption spectra optical band gap energy (Eg)-indirect transition, Urbach energy and optical basicity were estimated. FTIR spectra were recorded for all the samples in the range 400 cm^?1 to 4000 cm^?1. The FTIR absorbance spectra unveiled the SABV network structure mainly incorporating of BO₃ and BO₄ units. Raman spectroscopy is achieved to detect the structural changes and at higher wavenumber, B–O stretching modes in [BO₃] observed with one or two NBO's. The results of ESR spectra of glasses have indicated the highly covalent environment of vanadium ions. Analysis of the photon shielding parameters of the glasses which were obtained primarily from FLUKA Monte Carlo simulations and XCOM computations revealed photon energy and glass chemical composition dependence. The mass attenuation coefficient and effective atomic number ranged from 0.2668 to 0.3385 cm²g^-1 and 12.98–15.93 accordingly as the weight fraction of Sr increased from 16.06 to 26.72% in the glasses. Generally, photon shielding ability of the SABV glasses follows the trend: SABV0 > SABV1 > SABV2 > SABV3 > SABV4. The thermal neutron total cross section follows the same trend with values fluctuating between 71.9553 and 80.6268 cm^?1. However, SABV1 showed superior fast neutron moderating capacity among the glasses. The present SABV glasses showed outstanding photon shielding ability compared to common shields. The prepared glasses are thus suitable candidates for radiation protection applications.     

Thermal expansion and characteristic points of –Na2O–SiO2 glass with added oxides

A differential method with an optical lever system was used to determine the thermal expansion of the glasses based on Na₂O–SiO₂ and containing the following oxides: Al₂O₃, CaO, TiO₂, ZnO, Al₂O₃–TiO₂, CaO–TiO₂, or ZnO–TiO₂. The determination was carried out on both as-drawn and annealed rods. The influence of the thermal history as well as of the added oxide(s) on the thermal expansion of glasses is dealt with in this paper. The experimental results for the thermal expansion of annealed rods show that the addition of CaO–TiO₂ in the glass has the lowest value while the addition of CaO in the glass has the highest value for the coefficient of linear expansion. At the same time, the characteristic points of the annealed glasses, determined from the expansion-temperature curves, show that the addition of ZnO in the glass has the lowest values while the addition of TiO₂ in the glass has the highest values.     

Characterisation of glasses in the TeO2–WO3–PbO system

As potential candidates for photonic devices, non-linear materials and coatings, 22 glasses in the TeO₂–WO₃–PbO system have been formulated and prepared by conventional melting at temperatures ranging between 710 and 750 °C. The glass forming area has been determined for a wide region of the corresponding ternary diagram. Structural characterisation of the glasses was conducted through FTIR spectrometry and the variation of density values, which allowed calculation of the glass molar volume and the oxygen molar volume. UV–VIS spectra were recorded to determine optical absorption/transmission and energy gap values. Likewise, such results were correlated with the glasses composition and their ability for optical materials. DTA curves yielded data of transition temperature (T_g), onset crystallisation temperature (T_c) and the thermal stability range of glasses. Crystalline phases formed in devitrified and partially devitrified glasses were detected by X-ray diffraction. The properties and structural features of glasses were discussed in terms of their relative proportion of former/modifier oxides. The main glass former oxide is TeO₂, which arranges [TeO₄] groups with tetrahedral coordination, while PbO plays as glass modifier oxide. Tungsten oxide is incorporated as network former, alternating with TeO₂ and forming mixed linkages Te–O–W and W–O–W. WO₃ is the component that contributes most to increase the glass transition temperature, and to decrease both the oxygen molar volume and the thermal expansion coefficient.     

Effect of properties and crystallization behavior of BaO–ZnO–B2O3–SiO2 glass on the electrical conductivity of Cu paste

The extensive application of multilayer ceramic capacitors provides an attractive development for terminal electrode pastes. However, the growing requirement for advanced glass materials used in terminal electrode pastes is substantiated. Therefore, to advance the development of electrode pastes, better development and deeper exploration of glass powder are required. Here, a series of BaO–ZnO–B₂O₃–SiO₂ (BZBS) glasses were prepared by melt-quenching technique, which are used to investigate the effect of the introduction of BaO on structure and properties of the ZnO–B₂O₃–SiO₂ (ZBS) glass. With the introduction of BaO, the relative amount of [BO₄] was much less, which made the glass network structure loosen, decreased the glass transition temperature (T_g) and increased the coefficient of thermal expansion of the glass. The decreasing contact angle was observed on the surface of a barium titanate (BaTiO₃) substrate. When the BaO content was around 3–7 mol%, the stability of ZBS glass frit could be strengthened by inhibiting the precipitation of Zn₂SiO₄ crystal. In addition, to further characterize the effect of glass on terminal electrode paste, BZBS glass powder was adopted to prepare copper electrode paste, which was printed on the BaTiO₃ substrate and subsequently fired at 800°C for 10 min. With the related copper paste containing ZBS glass doped with 7 mol% BaO, the optimum value of acid resistance and sheet resistance (1.99 mΩ) were exhibited, at which the coated copper paste formed a dense conducting layer.     

Enhanced nonlinear optical and optical limiting properties of graphene/ZnO hybrid organic glasses

Graphene/ZnO (G/ZnO) composites were synthesized for the first time by a wet chemical method. X-ray diffraction and transmission electron microscopy analyses demonstrated that ZnO nanoparticles with an average diameter of about 5 nm uniformly covered the graphene surfaces. G/ZnO composites were dispersed in methyl methacrylate (MMA), polymerized at 75 °C for 30–35 min, and finally, dried at 45 °C for 10 h, to afford G/ZnO/PMMA organic glasses. UV–visible spectra showed that the band gaps of the G/ZnO/PMMA organic glasses were about 3.54 eV, larger than that of bulk ZnO because of the small size effect of ZnO nanoparticles. The nonlinear optical (NLO) and optical limiting (OL) properties of the G/ZnO/PMMA organic glasses were investigated by a modified Z-scan technique. The total NLO coefficient α₂ of the G/ZnO/PMMA organic glass was as high as 1530 cm/GW, which was approximately 5.6 and 7.8 times larger than those of G/PMMA and ZnO/PMMA organic glasses. The enhanced NLO properties of the G/ZnO/PMMA organic glasses led to excellent OL performance, which was attributed to the positive synergistic effects between graphene and ZnO.     

Properties of silver phosphate glass doped with nanosize zinc oxide

High valence cations when doped in phosphate glasses, modify the properties, basically due to changes in glass structural network, through formation of cross-linked bonds. In the present paper 5, 10, 15 and 20 wt% nanosize ZnO were doped in Ag₂O–P₂O₅ glass prepared by melt-quench method. Glass transition temperatures were determined by DSC technique, whereas structural investigations were carried out by FTIR spectroscopic technique. X-ray diffraction studies showed that all the prepared glasses are poorly crystalline. SEM studies were made to have an idea about morphological changes in the presence of nanosize ZnO. Electrical conductivities and dielectric constants were measured as a function of temperature and frequency. Cole–Cole plot indicated that grain boundary and relaxation processes affected the electrical properties. It was found that glass transition temperatures increased in the presence of ZnO and conductivities increased with frequency.     

Environmental influence of high Na2O additions on microstructure and ligand field parameters of Cr3+ inside borosilicate glass

A glass system based on the Na₂O/B₂O₃-doped CrO₃ borosilicate has been prepared by the melt quenching technique. The structure, color, optical absorbance and ligand field parameters were investigated for a wide range of Na₂O additives (20–60 mol%). All X-ray photoelectron spectroscopy (XPS) profiles were used to study the chemical shift states of the glass-constituting elements. Fourier transform infrared (FTIR) analyses explored the internal structure and subnetwork units. Furthermore, from the FTIR results, we concluded the transformation of trigonal borate units (BO₃) to tetrahedral borate units (BO₄) and the possibility of transformation from B₃-O-Si linkages to B₄-O-Si linkages. Despite the fixed CrO₃ content, the doped glasses showed a color transition from green to yellow with additional Na₂O content. The increased intensity of the band at 451–427 nm and the decreased intensity of the band at 619–627 nm are the main reasons for this color transformation. The optical absorption spectra confirmed the existence of Cr³⁺ and Cr⁶⁺ states. A decreasing behavior for the crystal field splitting (10Dq) and an increasing behavior for Racah parameter (B) were obtained with further Na₂O additives. The decreasing behavior of 10Dq was attributed to reduced oxygen concentrations with more Na₂O/B₂O₃ substitutions. The increasing behavior of B reflects the tendency of the bond between the Cr cations and their oxygen ligands towards an ionic nature. Moreover, the Dq/B values indicated that Cr³⁺ cations are in high-field positions for the glass sample containing 20 mol% Na₂O, and Cr³⁺ cations are in intermediate field positions for the glass sample containing 30 mol% Na₂O. However, for the glass samples doped with 40, 50 and 60 mol% Na₂O glass samples, Cr³⁺-cations are in weak field positions. These results of (Dq/B) recommend the glass sample doped with 20 mol% Na₂O for tunable laser applications.     

Influence of cobalt oxide on the structure,optical transitions and ligand field parameters of lithium phosphate glasses

The influences of cobalt oxide (CoO) additions on the structure, optical transitions, ligand field parameters and stability of lithium phosphate glasses have been investigated. A series of glass systems (LiPhCo-glasses) was successfully prepared through the melt quenching approach. The amorphous nature was confirmed from X-ray diffraction measurements. The density and molar volume followed the typical opposite behavior, where the latter showed a decreasing behavior with CoO additions. Furthermore, it was found that the LiPhCo-glasses gradually changed their color from colorless (Co-free sample) into bluish glasses with CoO additions, thereby evidencing the presence of Co²⁺ ions. This is consistent with the absorption band identified in the optical absorption spectra at ~562–572 nm, which is related to ⁴A₂(⁴F) →⁴T₁(⁴P) electronic transitions of Co²⁺ (3d⁷ electronic configuration) in tetrahedral symmetry. Additional absorption band is detected at ~1412–1448 nm, which is correlated to ⁴A₂(⁴F) →⁴T₁(⁴F) transitions of Co²⁺ ions in tetrahedral symmetry. These two absorption bands were employed to study the ligand field splitting ($10D{q}_{\mathrm{t}}$)and Racah parameter (B), which sheds the light into the bonding character between Co ions and its ligands. The analysis showed that $10D{q}_t$ (B) is increased (reduced) indicating more covalency and less stability within the glass matrix with Co additions.     

Optimized structural and mechanical properties of borophosphate glass

A series of phosphate glasses composed of (65-x)P₂O₅–15BaO–5Al₂O₃–5ZnO–10Na₂O-xB₂O₃ (x = 0, 2, 4, 6, and 8 mol%) were successfully prepared using the melt-quenching method. The effects of the addition of boron trioxide (B₂O₃) on the physical, structural, and mechanical properties of the glasses were investigated. As the added content of B₂O₃ increased from 0 to 6 mol%, the glass exhibited increased density and transition temperature, and decreased molar volume, indicating optimization of the glass stability. Raman spectroscopy revealed that the introduction of B₂O₃ transformed the glass from a chain structure to a three-dimensional network structure, which enhanced the chemical stability of the glass by the cross-linking of long phosphate chains with boron ions. Regarding the mechanical properties, when the boron content was 6 mol%, the flexural strength of the glass was 41% higher than that of the undoped boron, while the Vickers hardness and Knoop hardness values increased by 20.58% and 7.05%, respectively, and the fracture toughness was slightly decreased. In general, improving the mechanical properties of phosphate glass is of great significance for increasing the applications of this glass.     

Effect of Zr ions on the structure and optical properties of lithium borosilicate molybdate glass system

The glass system with the composition [(20-x) MoO₃– x ZrO₂–15 SiO₂– 65 Li₂B₄O₇, x = 0, 1, 2, 3, 4, and 5 mol %] was successfully synthesized using the melt quenching method. The XRD results of this glassy system confirmed the glassy nature of the prepared glasses. The density of this glassy system presented higher values while the molar volume provided lower values with increasing ZrO₂ content. The FTIR result showed that the spectrum of each sample consisted of broad bands that de-convoluted into several peaks. These peaks were characterized and the structure of each sample was recognized. Additionally, the optical measurements showed that sample x = 0 mol% provided a sharp ultra-violet cut-off at 380 nm, while the other samples showed a transition peak in the (210–230) nm range. The energy of optical band gaps of these glass samples decreased and the Urbach energy increased by increasing ZrO₂ content. Moreover, the different optical parameters of these glass samples were calculated and showed that the studied glasses could be considered promising materials to be used in different optical applications such as nonlinearity and optoelectronics.     

Compositional dependence of the optical properties of novel Ga–Sb–S–XI (XI = PbI2, CsI,AgI) infrared chalcogenide glasses

A novel family of Ga₂S₃–Sb₂S₃–XI (XI = PbI₂, CsI, AgI) was investigated to understand the role of metal halides and exploit new chalco‐halide glasses for infrared optics. The dependence of the thermal properties, infrared optical properties, and structural information of the novel family on different metal–iodines was investigated. Results showed that metal halides increase the glass stability but decrease the glass network connectivity. The compositional dependence of the short‐wave cut‐off edge is associated with the electronegativity difference between the cations and anions of the metal halides. Raman study showed that the metal–iodine modified the glass structure mainly through the iodide content, and the cations dissolved in the glass network mostly as charge compensators for the aperiodic network. For the glasses in the series Ga₂S₃–Sb₂S₃–XI–Dy³⁺, Dy³⁺ emission increased in the PbI₂‐ and CsI‐doped glasses but decreased in the AgI‐doped glass due to the combined effect of dysprosium and oxygen. For all that, these novel glasses are highly promised for use in infrared optics.     

Effect of silver oxide additives on structural,optical dispersion and protection features of lead boro-phosphate glasses

This work presents the structural, optical, refractive index dispersion, and shielding properties of Ag-containing lead-boro-phosphate glasses. The glasses were prepared using the classic melt-quenching method, in which the Ag₂O concentration was varied in each synthesis. The precipitation of Ag NPs was proved by the appearance of the (200) crystal plane in the XRD patterns and confirmed by the homogeneous distribution of spherical agglomerates observed in TEM images. FTIR and Raman analyses have revealed a network depolymerization process resulting from the distortion of the PO₄ units and the formation of Ag NPs. Therefore, the Ag ions contribute at high concentrations to an increase in the glass density and a reduction in the optical band gap energy. Ellipsometry parameters indicate that the glass becomes more optically dispersive due to the Ag NPs formation, which improves its performance for several potential applications in multi-functional optical devices. The mass attenuation factors are determined in the energy range of 15 keV–15 MeV and are very sensitive to the silver content at low energies. The Half value layer (HVL) decreases with the amount of Ag₂O, indicating the improvement in the material's ability to attenuate radiation. The results show that the glass sample with the highest Ag content has the highest shielding effectiveness.     

Synthesis,Characterization and Biological Evaluation of a New Sol-Gel Derived B and Zn-Containing Bioactive Glass: <Emphasis Type="Italic">In Vitro</Emphasis> Study

In this study we employed the sol-gel method to synthesize new CaO–P₂O₅–SiO₂–ZnO–B₂O₃ bioactive glasses. Three samples with various B₂O₃ content (5, 10 and 15 mol %) was prepared and their bioactivity were evaluated by immersion in simulated body fluid (SBF) and the glasses were characterized using X-ray diffraction (XRD), Fourier transform infrared (FTIR) and scanning electron microscopy (SEM). The experimental results revealed that with increasing the amount of boron content, a more crystalline domain can be observed in their XRD patterns and consequently the formation of hydroxyapatite (HA) increased. FTIR spectra showed that the sample containing 10 mol% of boron had the sharpest peaks attributed to the formation of hydroxyapatite. Biocompatibility of the samples was examined by MTT assay and alkaline phosphatase activity. The result ascertained that the synthesized bioactive glass had good biocompatibility and can serve as a bone substitute in bone defects.