Increase In Optical Basicity Research Articles

Effect of ZnO on the structure, optical properties and ESR studies of B2O3–Na2O–SrO–Fe2O3–ZnO glass system

Iron oxide-doped borate glass with composition [(63-x)B2O3 – 10Na2O – 25SrO – 2Fe2O3 – (x)ZnO; x=0, 2, 4, 6, and 8 mol%] was prepared following melt-quench technique. The absence of sharp peaks in the X-ray diffraction (XRD) spectra confirmed the amorphous nature. Furthermore, Fourier transform infrared (FTIR) spectroscopy was employed to study the structure and subnetwork units inside the glass matrix. Moreover, the density and molar volume values were assessed for supplementary studies about the glass structure. Also, the present glass system's optical properties and electron spin resonance were considered. FTIR spectra showed that the basic structural units are trigonal BO3 units, BO4 tetrahedral coordinated units and nonbridging oxygens. Here, a tendency towards the back conversion of BO4 units to BO3 and nonbridging oxygen was also indicated for the further ZnO contents concurring with the optical band gaps and Urbach energy trends. Moreover, FTIR outcomes supported the presence of ZnO as a glass modifier in the form of octahedral coordinated units (ZnO6). Furthermore, the optical bandgaps exhibit a decreasing trend with excessive ZnO contents which is attributed to the increase in optical basicity from 0.681 to 0.729 and the increase in polarizability from 1.690 to 1.776 as well as the creation of nonbridging oxygen. In addition, the metallization criterion values decreased from 0.376 to 0.355 with more ZnO concentrations. Such behavior indicates it is favored towards metallic behavior. Furthermore, the decreased values of g and increased polarizability increase the nonlinear properties of the present glasses. The electron spin resonance spectra show resonance signals at g = 4.12 and 2.04. The resonance signal at 4.12 associated with Fe3+ ions mainly located in rhombically distorted tetrahedral or octahedral coordination. The g = 2.04 resonance signal is ascribed to dipolar interactions. The obtained results suggest that the proposed glasses can be used in nonlinear optical applications.

Physical and optical properties of CdO B2O3 Bi2O3 TeO2 glass system

The physical and optical properties of xCdO (35-x) B2O3 60Bi2O3 5TeO2 glass system (where, x=10, 20, 30) has been investigated. Thermal stability , density , optical transmittance and the refractive index of these glasses have been studied. It was found that the values of density increase but the values of molar volume and oxygen packing density decrease by increasing CdO content. Also, the thermal stability of all the studied samples increase by increasing CdO content. However, it was found that the values of optical energy gap decrease by increasing CdO content for all the studied samples. While as the values of refractive index, molar polarizability, oxide ion polarizability, optical basicity increase by increasing CdO content. Also, all the studied samples exhibit insulating behavior and become more basic and more polarized by increasing CdO content. The high values of third order nonlinear optical susceptibility for all the studied samples, were found to be in the range (1.408-2.307)x 10-12esu, which is larger than that of pure silica glass. Finally, it has been suggested that all the studied samples are promising materials for nonlinear optical requests.

The Importance of Slag Structure to Boron Removal from Silicon during the Refining Process: Insights from Raman and Nuclear Magnetic Resonance Spectroscopy Study

Slag structure plays an important role in determining the relative ease of boron removal from silicon. Correlation between slag structure and boron removal thermodynamics was experimentally studied by Raman and nuclear magnetic resonance (NMR) spectroscopy using CaO-SiO2-Na2O slags with different optical basicities (0.6 to 0.71). Optimization of slag depolymerization leads to efficient removal of boron. The extent of nonbridged oxygen content (NBO/T) and boron removal gradually increased with an increase in optical basicity from 0.6 to 0.66: B2O3 derived from boron oxidation captured nonbridging oxygens of Q 0(Si), Q 1(Si), and Q 2(Si), and was incorporated into the silicate network in the form of Q 3(Si and B). When optical basicity increased to 0.71, NBO/T rapidly increased and boron removal decreased considerably. Quick depolymerization of Q 3(Si and B) deteriorated the stability of boron. Various structural forms of boron in the silicate network were successfully detected: the BO3 trihedrons [3]B-3Si, [3]B-2Si-1NBO, and BO3 (nonring), and the BO4 tetrahedrons BO4 (1B, 3Si) and BO4 (0B, 4Si). BO4 (1B, 3Si) was the main structure contributing to the increase of boron capacity; BO3 (nonring), detected under higher optical basicity conditions, may cause deterioration of boron removal by suppressing its oxidation.

Near infrared luminescence of bismuth-doped MO-B2O3 (M=Ca, Sr, Ba) glasses

Bi-doped MO-B2O3 (M=Ca, Sr, Ba) glasses were prepared by melting method. Excitation spectra, visible and infrared luminescence spectra were measured. Near infrared (NIR) emissions located at about 1190 nm with FWHM only 40 nm and at 1300 nm with FWHM about 200 nm can be observed in different samples when excited by 808 nm LD excitation. The two emission bands have different excitation bands. Red emission centered at 660 nm related to Bi2+ can be observed in some samples. The NIR emission at 1300 nm band disappears with the increase of optical basicity, while that of the NIR emission at 1190 nm band shows a contrary tendency. We proposed that the NIR emissions located at 1190 nm and 1300 nm originated from different bismuth centers. The infrared emission peak at about 1300 nm derives from low valence Bi ions according to the Duffy’s theory of optical basicity.

高Tb3+离子含量磁光玻璃的Faraday效应及发光性能

采用高温熔融法制备了高Tb3＋离子含量的GeO2-B2O3-SiO2系统磁光玻璃,测试了其Verdet常数和发光性能,探究了玻璃的Faraday效应、发光性能及光学碱度。研究结果表明：Verdet常数和光学碱度均随着Tb2O3含量的增加而线性增大,当Tb2O3摩尔分数为70%时,Verdet常数达到-5 000 min·T^-1·cm^-1（632.8nm）,所有磁光玻璃样品随Tb2O3含量变化均发出明亮的黄绿光。由于浓度猝灭效应,高Tb2O3含量缩短了Tb^3＋离子间距,增强了交叉弛豫效应,降低了发光强度和荧光寿命。

Representation of Oxidation Ability for Metallurgical Slags Based on the Ion and Molecule Coexistence Theory

AbstractThe defined oxidation ability of metallurgical slags based on the ion and molecule coexistence theory (IMCT), i.e., the comprehensive mass action concentration of iron oxides, has been verified through comparing the calculated and the reported activity of iron oxides in the selected FetO‐containing slag systems. To calculate the defined comprehensive mass action concentration of iron oxides in the selected slag systems, a thermodynamic model for calculating the mass action concentrations of structural units or ion couples in CaO–SiO2–MgO–FeO–Fe2O3–MnO–Al2O3–P2O5 type slags, i.e., the IMCT‐Ni thermodynamic model, has been developed. The defined comprehensive mass action concentration of iron oxides is more accurate than the measured activity of iron oxides to represent the slag oxidation ability of the selected FetO‐containing slag systems. The calculated comprehensive mass action concentration of iron oxides or the reported activity of iron oxides in the selected FetO‐containing slag systems shows an increase tendency with an increase of optical basicity of the slags by taking as 0.93 and as 0.69, or as 1.0 and as 0.75, rather than by taking as 0.51 and as 0.48. The slag oxidation ability represented by the defined comprehensive mass action concentration of iron oxides or the measured activity of iron oxides is not only decided by the effects of iron oxides, but also by the comprehensive effects of both iron oxides and basic oxides as CaO or MgO or MnO in the selected FetO‐containing slag systems.

Optical absorption and structural studies of bismuth borate glasses containing Er3 + ions

Glasses with composition xBi2O3–24Na2O–(75−x)B2O3–1Er2O3 (where x=0, 5, 10, 15, 25, 33, 40mol%), were prepared by the melt quenching technique. The effect of Bi2O3 content on thermal stability, optical properties and structures of these glasses is systematically investigated by X-ray diffraction, infrared spectroscopy and DTA techniques. The variations in the optical band gap energies, with Bi2O3 content have been discussed in terms of changes in the glass structure. Urbach energy increases with increasing Bi2O3 content in the present glass system. It is found that the density, molar volume and optical basicity increase with increasing Bi2O3. The glass transition temperature (Tg) of the samples was found to decrease with the Bi2O3 content. IR measurements revealed an existence of trigonal BO3 pyramid, tetrahedron BO4, pyramidal BiO3 and octahedron BiO6 structural units in the network of the investigated glass. Furthermore, a decrease in BO4 and an increase in BO3 take place against the increase of x which means that, Bi2O3 plays the role of network modifier in the structural network.

Properties and Structures of Bi2O3–B2O3–TeO2 Glass

Glass formation range of Bi2O3–B2O3–TeO2 system has been investigated (B2O3 ≤ 40 mol%). Four glasses with compositions xBi2O3–30B2O3–(70–x)TeO2 (x = 40, 50, 60 and 70 mol%) have been prepared by using melt quenching technique. The effect of Bi2O3 content on thermal stability, optical properties and structures of these four Bi2O3–B2O3–TeO2 glasses is systematically investigated by inductive coupled plasma emission spectrometer (ICP), differential scanning calorimetry (DSC), Raman spectra and X-ray photoelectron spectroscopy (XPS). It is found that the density, refractive index and optical basicity increase with increasing Bi2O3. The Raman spectra and XPS spectra show that the glass network is mainly constituted by the [BiO6] octahedron, [TeO4] trigonal bipyramidal, [TeO3] trigonal pyramid, [BO3] trigonal pyramid and [BO4] tetrahedron structural units. With increasing Bi2O3, the coordination number around B atom changes from 3 to 4 and [TeO4] units are converted to [TeO3] units. Bi5+ ions may exist in Bi2O3–B2O3–TeO2 (BBT) system and their amount grows with increasing Bi2O3 content.

EPR and Optical Absorption Spectral Investigations of Cu2+ in Bi2O3-ZnO-B2O3-Li2O Glasses

Electron paramagnetic resonance and optical absorption studies of Bi2O3-ZnO-B2O3-Li2O glasses were made by introducing Cu2+ as spin probe. The EPR spectra of Cu2+ in all the glass samples recorded in the X-band frequency have similar spectral features. The variation in glass composition influences the spin Hamiltonian parameters calculated from the spectra. The spin Hamiltonian parameters indicate that the Cu2+ ions are coordinated with six ligand atoms in a distorted octahedron elongated along one of the axes and the ground state of the Cu2+ is dx2−y2 orbital. The optical absorption spectra exhibited a broad band corresponding to d-d transition bands of Cu2+ ion. The values of bonding parameters indicate a covalent nature for the in-plane σ bonding and pure ionic nature for the in-plane and out-of-plane π bonding. The theoretical optical basicity parameter values were evaluated, and it was observed that the value of Γσ increases whereas Γπ decreases with the increase in optical basicity.

Optical Investigation and Electronic Polarizability of Nd3+ Doped Soda-Lime-Silicate Glasses

Problem statement: This study researched on different physical and optical properties of Nd3+ doped soda-lime-silicate glass. The glasses containing Nd3+ in (65-x)SiO2: 25Na2O: 10CaO: xNd2O3 (where x = 0.0-5.0 mol%) had been prepared by melt-quenching method. The density and molar volume increase with increasing of Nd2O3 concentration due to increasing of Non Bridging Oxygen (NBOs) in glass matrix. The optical spectra were measured and evaluated their optical band gap and found to decrease with increasing of Nd2O3 concentration. Moreover, these results showed that the refractive index of glass does not only depend on the density but also depend on the electronic polarizability of the glass. The values of polarizability of oxide ions, theoretical optical basicity were also determined. Approach: This study investigated the effect of Nd2O3 content on optical band gap, density, molar volume, optical basicity and polarizability in soda-lime silicate glass. Series of Nd3+ doped soda-lime silicate glasses (in mol%): (65-x)SiO2-25Na2O-10CaO-xNd2O3 (x = 1-5 mol%) were prepared by the normal melt-quenching technique. Analytical reagent grade chemicals of SiO2, Na2O, CaO and Nd2O3 were used in the glasses preparation. Each batch of chemical was powdered finely and mixed thoroughly in porcelain crucibles and was later melted in an electrical muffle furnace for 3 h, at 1200°C. After complete melting, the homogenized melt was quickly poured onto a stainless steel mould that was heated at 500°C to form the glasses. The glass blocks thus resulted were immediately transferred to the annealing furnace that and were annealed at 500°C for 3 h and then slowly cooled down to the room temperature in order to remove possible thermal stains in the glasses. Finally, the as-prepared glass samples were cut and then finely polished to a thickness of 3 mm. The glass densities were measured by using xylene as an immersion liquid based on the Archimedes's principle. Glass refractive indices were measured at room temperature using an Abbe refractometer (ATAGO) and mono-bromonaphthalene as an adhesive coating. The optical absorption spectra of Nd3+ doped soda-lime silicate glasses were recorded at room temperature using a UV-VIS spectrophotometer (Hitachi, U-1800), working in 300-700 nm. Results: By addition of Nd2O3 into the SiO2-Na2O-CaO glass network, the density increases with increase in Nd2O3 content. The molar volume of the glass systems under study increases with increase in Nd2O3 content, which is attributed to increase in the number of Non Bridging Oxygen (NBOs). The optical band gap slightly decreases with the increase of Nd2O3 and results in the increase of bonding defect and non-bridging oxygen. The optical basicity of the glasses are increasing with Nd2O3 content change with the increasing of polarizability and consequently the increase in refractive index. Conclusion: The study of SiO2-Na2O-10CaO-Nd2O3 glass systems showed that the density and refractive index increase with increasing concentration of Nd2O3. The increase of molar volume with Nd2O3 content indicates that the extension of glass network is due to the increase of the number of NBOs. The optical band gap slightly decreases with in Nd2O3 content due to an increase in the degree of localization of electrons thereby increase of the donor center in the glass matrix. The electronic polarizability and optical basicity increase with the increase of mol% of Nd2O3, which is in agreement with the decrease of optical band gap. Moreover, the results found in this study show that the refractive index of glass does not only depend on the density but also depend on the electronic polarizability of the glass.

Infrared, Raman and XPS spectroscopic studies of Bi 2O 3–B 2O 3–GeO 2 glasses

Glasses with composition 50Bi 2O 3–(50 − x) B 2O 3– xGeO 2 ( x = 0, 5, 10, 15 mol%) were prepared by conventional melting method. The thermal properties were investigated by differential thermal analysis (DTA) and the structures of the glasses were probed by Infrared, Raman and X-ray photoelectron spectroscopy (XPS). The results show that density, refractive index and optical basicity increase with the increase of GeO 2. The glass transition temperature ( T g), onset crystallization temperature ( T x) and Δ T ( T x − T g) increase as well. The cut-off edges in ultraviolet and infrared shift to longer wavelength by the addition of GeO 2. Infrared, Raman and XPS results indicate that the glass network consists of [Bi–O 6] octahedron, [BO 3] triangle, [BO 4] tetrahedron and [GeO 4] tetrahedron and borate oxide mainly exists in [BO 3] units. XPS result indicates Ge 4+ ions form steady [GeO 4] tetrahedra units in the glass network and the number of non-bridging oxygens decreases with the addition of GeO 2.

Infrared, Raman and XPS spectroscopic studies of Bi 2O 3–B 2O 3–Ga 2O 3 glasses

Glasses with compositions 60Bi 2O 3–(40−x)B 2O 3–xGa 2O 3 ( x = 5, 10, 15, 20 mol%) are prepared by conventional melting method. The thermal properties are investigated by differential thermal analysis (DTA) and the structures of the glasses were probed by Infrared, Raman and X-ray photoelectron spectroscopy (XPS). The results show that density, refractive index and optical basicity increase with the increase of Ga 2O 3. The glass transition temperature ( T g), the onset crystallization temperature ( T x), Δ T ( T x− T g) decrease with the content of Ga 2O 3. The cut-off edges in ultraviolet and infrared shift to longer wavelength with the increase of Ga 2O 3. On the other hand, the addition of Ga 2O 3 causes a progressive coordination number change of the boron atom from 3 to 4. XPS result indicates both Bi 5+ and Bi 3+ exist in 5 mol% Ga 2O 3 content, while Bi 5+ amounts decrease with the increase of Ga 2O 3 contents. The glass is mainly composed of [BiO 6], [BO 3], [BO 4] and [GaO 4] polyhedra. Glasses are supposed to have layer structure. [BO 3] triangle and [BO 4] tetrahedra may be located between the [GaO 4] tetrahedral and [BiO 6] octahedra to prevent crystallization and to compensate electric charge.

Average electronegativity, electronic polarizability and optical basicity of lanthanide oxides for different coordination numbers

On the basis of new electronegativity values, electronic polarizability and optical basicity of lanthanide oxides are calculated from the concept of average electronegativity given by Asokamani and Manjula. The estimated values are in close agreement with our previous conclusion. Particularly, we attempt to obtain new data of electronic polarizability and optical basicity of lanthanide sesquioxides for different coordination numbers (6–12). The present investigation suggests that both electronic polarizability and optical basicity increase gradually with increasing coordination number. We also looked for another double peak effect, that is, electronic polarizability and optical basicity of trivalent lanthanide oxides show a gradual decrease and then an abrupt increase at the Europia and Ytterbia. Furthermore, close correlations are investigated among average electronegativity, optical basicity, electronic polarizability and coordination number in this paper.

UV transparency and structure of fluorophosphate glasses

Ultraviolet (UV) transparency and local structural environment of fluorophosphate glasses in the Ba(PO 3) 2–MgF 2–CaF 2–AlF 3 system have been studied with increasing fluoride content (covering the whole compositional range) by infrared (IR) reflection spectroscopy (IRRS) in conjunction with 31P magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy. UV cutoff of the glasses shifts towards longer wavelength with increasing fluoride up to ∼36 mol%. IRRS spectra indicate a gradual increase in nonbridging oxygens (NBOs) in this region. According to 31P MAS NMR spectra, it is due to the combined effects of gradual increase in Q 1 sites and P–O–Al bridges (increase in optical basicity). Beyond ∼36 mol% fluoride content, the UV cutoff shifts towards shorter wavelength. It is attributed to decrease in NBOs or Q 1 sites (decrease in optical basicity) as revealed in the IRRS and 31P MAS NMR spectra, respectively. In this region, true partial role of the metal fluorides in controlling UV transparency has been found to contribute significantly as well.

Effect of vacuum dehydroxylation on the UV transparency and structure of metaphosphate glasses

UV cutoff of calcium metaphosphate glass shifts towards shorter wavelengths in the initial stage dehydroxylation in vacuum. IR reflection spectral study reveals that it is due to the combined effects of polymerization of the phosphate glass network and formation of small metaphosphate rings caused by the decrease in OH content. This is supported by the decrease of Q 2 sites (decrease in optical basicity) in the 31P MAS NMR spectra. On further dehydroxylation, the shifting of UV cutoff towards longer wavelengths is attributed to the increase of Q 1 and Q 2 sites (increase in optical basicity) associated with the formation of nonbridging oxygens (NBOs). It is caused by the preferential loss of P 2O 5 and simultaneous decrease of OH groups during exhaustive dehydroxylation for a prolonged period of melting in vacuum.

A structural interpretation of the Pb 2+, Eu 3+ and Nd 3+ optical spectra in doped sodium borate glasses

The study of sodium borate glasses over the compositional range 10–35 mol.% Na 2O by using Pb 2+, Eu 3+ and Nd 3+ as local sounds shows the existence of two possible situations depending on whether the Na 2O content is lower or higher than about 25 mol.%. In the first composition range the simultaneous increase of optical basicity and of modifier ion site asymmetry implies rather a 2D-character of the network former. The properties of the glasses with high Na 2O content involve more 3D-character for the former sublattice.