Formation Of Non-bridging Oxygen Research Articles

Impact of Bi2O3 on the glass system B2O3 -TeO2–MgO–PbO on the purpose of radiation shielding efficacy

In this study, eight glass samples were prepared with the composition of [x Bi2O3-(75-x) B2O3–15TeO2 –5MgO–5PbO; where x = 0, 10, 20, 25, 30, 40, 50, and 60 mol%]. In the composition of those glass samples, various amountsof B2O3 were replaced by Bi2O3 to improve the glass material's radiation shielding capability. The mechanical properties of these glasses have been evaluated using densimeter and microhardness. The Vickers microhardness (Hv) slightly decreases as the amount of Bi2O3 increases due to the formation of Non-Bridging Oxygen (NBO). To evaluate the radiation shielding effectiveness of the prepared glass samples, we performed Monte Carlo simulations of several shielding parameters. The mass attenuation coefficients of the experimentally produced BTMPBi glass series were calculated using NIST and MCNP6, and reasonable agreement was found between the simulation and experimental results. The relative difference between NIST and MCNP6-based results was calculated, and the maximum deviation was 2.21% for the 1173 keV gamma ray incident in the BTMPBi60 glass sample. The value of the mean free path of those prepared glass samples maintained the following trend - BTMPBi0> BTMPBi10> BTMPBi20> BTMPBi25> BTMPBi30> BTMPBi40> BTMPBi50>BTMPBi60. The prepared glass sample BTMPBi0 showed a 2.6 times higher value of the mean free path at energy 1332 KeV compared with the prepared BTMPBi60. Analyzing the composition of the prepared glass samples, it is clear that the greater the amount of Bi2O3 the greater the value of linear attenuation coefficient (LAC) and effective atomic number. Based on the results, it can be concluded that the glass sample containing 60 mol % of Bi2O3 (BTMPBi60) exhibited the highest radiation shielding capability among all of the prepared samples.

Correlations of structural, thermal and electrical properties of sodium doped complex borophosphosilicate glass

Borophosphosilicate glasses with varying sodium ion concentrations were investigated for their, structural, thermal, and electrical properties. All the obtained glasses were transparent except the glass with the highest sodium content, which exhibited translucency due to inhomogeneities. Increasing sodium content led to reduced boron and silicon content while maintaining a constant B/Si ratio, indicating progressive depolymerization of the glass network. Confocal microscopy, scanning electron microscopy, and atomic force microscopy showed homogeneous and granular structure for samples with lower sodium content, but higher sodium content resulted in visible agglomeration/nanocrystallization. X-ray diffractograms showed amorphous nature for most samples, with samples doped with the highest concentrations of Na2O showing several broad reflections suggesting nanoscale crystallinity. Fourier-transform infrared spectroscopy revealed shifts in dominant bands with increasing sodium content, indicating depolymerization of the borate network. An observed decrease in glass transition temperature and thermal stability with increasing sodium content was attributed to depolymerization and formation of non-bridging oxygens. Impedance spectroscopy revealed two relaxation processes associated with the transport of Na+ ions through two different regions. DC conductivity and activation energy predominantly increased with the sodium ion content at high temperatures.

Enhanced white light emission and quantum efficacy of borate-zinc–lithium-aluminium glasses doped with Dy2O3 for potential white light emission applications

The pursuit of efficient and enhanced white light emission in glasses doped with rare earth ions is a noble endeavour, one that has the potential to revolutionise many industries and benefit countless individuals. In view of this, we have prepared the Dy3+ ions doped Borate-Zinc–Lithium-Aluminium glasses via melt-quenching methods and their properties were meticulously studied using XRD, Raman, FTIR, DSC, Luminescence and time decay kinetic studies. To evaluate the influence of Dy2O3 doping, various physical parameters were analysed. The integration of Dy2O3 into the host glass matrix causes significant changes in the numerous physical parameters due to the geometrical structural change, resulting in the formation of non-bridging oxygens (NBOs), resulting in the increased compactness, thus the density and refractive index of the glasses. The DSC profile analysis reveals the thermal stability of the glasses. The UV–visible–NIR absorption spectra reveal the presence of a pronounced peak, owing to a hyperfine transition and other transitions dependent on the host. Furthermore, the Judd-Ofelt theory was applied to support the experimental results and evaluate the radiative parameters and efficiency. It was discovered that the JO parameters are in the following order: Ω2> Ω6> Ω4. The luminescence emission enhancement was observed with Dy2O3, up to 0.75 mol%; beyond that, the concentration quenching effect was observed. The glasses were proficiently fitted to the Inokuti-Hirayama model. Colorimetric parameters such as CIE coordinates, correlated colour temperature, and yellow-to-blue intensity ratios were estimated. It was discovered that, the sample containing 0.75 mol% of Dy2O3 doped glass is capable of white light emission with 72 % efficiency under excitation of 349 nm. Overall, present studies demonstrate that the thermal stability of glasses with phonon energy of 1330 cm−1, when stimulated at 349 nm and capable of producing white light, offers considerable benefits in relevant applications in the field of wLEDs.

Structural and optical investigations of RE3+: Yb, Er, Sm, Nd, Ce-doped multi-functional silica glasses for photonic applications

The influence of various trivalent lanthanides was investigated in the silica phosphate multi-component glass matrix, synthesized by the sol-gel method. The prepared glasses were analyzed to explore the degree of bandwidth amplification for telecommunication systems, and the potentiality of lasing media and smart glass films. Alkaline earth metal ions of Ca2+ were effectuated as a glass modifier, mediating the formation of non-bridging oxygen with the glass formers, and imputing favorable structural attributes to the glasses for versatile applications. The bonding parameter derived from the average nephelauxetic ratio implies covalency around the rare earth ion sites in the Er3+ and Nd3+ doped systems, while the Sm3+ doped glass exhibits ionicity. In the silica-based glass matrix singly doped with Yb3+, the coexistence of Yb3+/Yb2+ ions was evidenced. Transitions across 4f14 and 4f135d levels of Yb2+, with an experimental lifetime of 45.8 ns would provide prospective pulsed yellow lasers, for non-invasive therapeutics. Er3+ doped glass evinced a large bandwidth of 93.775 nm at 1477 nm and a high quantum efficiency of 97%, favorable for O + E + S-band telecommunication networks. The transition corresponding to 4G5/2→6H7/2 of Sm3+ and 2G7/2→4I9/2 of Nd3+ is suggestive that the respective doped glasses could be devised into solid-state red and green laser sources. Novel near-infrared emission at 1476 nm was also evidenced in the Sm3+ and Nd3+ doped systems. Prominent absorption at 280 nm and complete transparency in the visible region observed in the Ce3+ mono-doped system make it ideal for smart glasses as UVB and UVC shielding films.

Physical and optical traits of tellurite glass: effect of bimetallic TiO2/Au nanoparticles

The dependence of TiO2/Au concentrations on the physical and optical properties of glass was investigated thoroughly. Variations in density, molar volume, molar refraction, refractive index, and polarizability with varying TiO2/Au contents were affected by the formation of non-bridging oxygen. The formation of big islands in the atomic force microscopy image signifies the growth of nanoparticles. The decrement in band gap manifests alteration in the glass network mainly the local field around the Er3+ ions. The rise in Urbach energy illustrates disorder in the glass. The beneficial features of the current glass composition may be useful for photonic devices.

Characterization of the anomaly in immediate aqueous interactions of sodium borate glasses by dynamic vapour sorption with in-situ Raman

This study applied a novel technique; dynamic vapour sorption (DVS) with in-situ Raman spectroscopy, as well as complementary techniques of attenuated total reflectance-Fourier transform infrared spectroscopy and X-ray diffraction, to investigate the effect of sodium content on the immediate aqueous reactivity and reactions of a range of melt-quench-derived binary sodium borate glasses (SBGs): xNa2O-(100-x)B2O3 (x = 18, 23, 30 and 35 mol%). DVS gravimetrically measured the effect of controlled relative humidity (RH) values on SBGs, while in-situ Raman monitored their structural changes in real time. It was found that the glass boron coordination, glass transition temperature, as well as weight change and percentage of crystallinity post exposure to vapour, along with threshold % RH to initiate sorption, and threshold time to initiate crystallization under 90% RH demonstrated the anomalous variation with increasing sodium content in glasses. Relative to other formulations, 30Na2O–70B2O3 showed the lowest weight change and crystallinity after vapour desorption, and highest threshold % RH and longest threshold time. There was also a correlation between vapour- and water-induced reactions, as determined by reaction rates and structural changes. Specifically, lower glass network connectivity or non-bridging oxygen formation fostered their crystallization when exposed to either vapour or water, leading to higher weight change in aqueous environments. In sum, the results of this study validated the coupling of DVS with in-situ Raman spectroscopy in characterizing the reactivity and mechanisms of aqueous interactions of SBGs.

Study on UV-laser fatigue damage of sol-gel antireflective coating using XPS and slow positron beam Doppler broadening spectrum

The fatigue damage behavior of antireflective coating over KDP crystal under vacuum environment was studied with varied UV-laser irradiation, and the dynamic process from initial damage to complete failure of this coating was obtained. Scanning electron microscope (SEM) and slow positron beam (SPB) technique was employed to study the macro- and micro-defects in the process of evolution. The formation of non-bridging oxygen (NBO) and the variation of O/Si ratio along the direction of coating depth were obtained during the damage process based on X-ray photoelectron spectroscopy (XPS). The idea that oxygen with low binding energy absorbs UV light and produces oxygen defects to induce damage was put forward, and the damage mechanism of sol-gel antireflective coating under UV-laser irradiation was given.

Optical Properties of Cerium Oxide Doped Zinc Borotellurite Glass

The addition of rare earth, zinc, and borate in tellurite glass was found can enhance the glass properties and overcome its existing weaknesses. These include improving the glass forming ability and stability. In this study, cerium-doped zinc borotellurite glasses were produced using conventional melt-quenching technique and the optical properties of the glasses were investigated. UV-VIS spectra show that the absorption edge shifted to a higher wavelength with CeO2 addition from 0 until 0.05 mol. Consequently, the direct and indirect optical band gap was found to decrease from 3.60 to 2.07 eV and 3.28 to 1.46 eV respectively. On the contrary, the refractive index was found to increase from 2.326 to 3.017. This is attributed to the presence of cerium ions and the formation of non-bridging oxygens. Besides that, the Urbach energy found to be maximum at 0.02 mol CeO2 and minimum at 0.00 mol CeO2. This indicates that there are some structural disorders occur in the glass network as CeO2 introduced into the system. The molar refraction, molar polarizability, oxide ion polarizability and optical basicity exhibited similar trend of data as the CeO2 content was increased which signifies the relation of these parameters. Meanwhile, the metallization criterion is reported to be decreased, indicating that the glass sample become more metallized with the addition of cerium oxide.

Influence of Eu3+ dopant on lithium barium gadolinium phosphate glass properties for orange-reddish photonic devices

The Eu3+-doped lithium barium gadolinium phosphate glasses were prepared using the conventional melt-quenching method with different concentrations of Eu2O3 and Gd2O3. The physical characteristics were determined by refractive index, density, molar volume, oxygen packing volume, and oxidation states. Moreover, the optical characteristics were investigated via photoluminescence spectroscopy (PL), UV-vis spectroscopy, Radioluminescence (RL), and decay time. It was found that the Gd2O3 concentration of 12 mol% was the optimum composition for further investigations of the Eu2O3 doping concentration optimization. The emission spectra of PL and RL showed the strongest intensity of orange-reddish emission (λEx = 394 nm) when the Eu2O3 concentration was at 0.3 mol% corresponding to energy transition from 5D0→7F0,1,2,3,4. The oxidation state of Eu3+ ions due to the formation of non-bridging oxygens (NBO) in the glass network was confirmed by using X-ray Absorption Near Edge Spectroscopy (XANE). Furthermore, the high transparency and fast decay time in the range of 2.4–2.8 ms displayed the potential to improve laser and radiation detector performances.

Influence of Vanadium Oxide on the Optical and Electrical Properties of Li (Oxide or Fluoride) Borate Glasses

Binary glass systems of the chemical composition 0.25Li2O–0.75B2O3 and 0.25LiF–0.75B2O3 with different additive ratios of V2O5 were prepared using the melt-quenching method. Characterization was carried out through different techniques such as Fourier-transform infrared (FTIR) and ultraviolet–visible absorption (UV–visible) spectroscopy. Optical and electrical properties have been investigated in order to recognize the role of V2O5 in glass. FTIR spectra of the studied glasses expose repetitive vibration curves with limited variations. BO4 and BO3 are the basic constituent units of the studied glasses in addition to the BO2F and BO3F units in the case of fluoro-borate glasses. Shifting to a higher wavelength in the optical absorption spectra and a decrease in the optical band gap values via increasing V2O5 content confirms the formation of non-bridging oxygen (NBO). The ac-electrical conductivity (σac) and the dielectric constants (ɛ′) of the glass samples were studied in the frequency range 102 Hz–8 MHz. The ionic conduction takes place by Li-ion movement in all samples. The electronic conduction of borate glass can be explained using hopping between V4+ and V5+. The results show excellent properties of the glass with a low concentration of vanadium oxide.Graphical

Compositional dependence of thermophysical properties in binary alkaline earth borate melts: Insights from structure in short-range and intermediate-range order

• Thermal conductivity of alkaline earth borate melts is investigated systematically for the first time using transient hot-wire method. • Thermal diffusivity is extrapolated from thermal conductivity, heat capacity and melt density, providing a new approach to thermal diffusivity measurement. • Short-range and intermediate-range order of alkaline earth borate structure is studied using high-resolution MAS-NMR, Raman spectroscopy and XPS for a precise and comprehensive insight into structure-conductivity relationship. • Compositional dependence of thermal conductivity is revealed with the discussion on “boron anomaly” phenomenon in alkaline earth borate melts. In this work, the thermal conductivity of alkaline earth borate melts was measured using hot-wire method from 1323 to 1623 K, and the thermal diffusivity was extrapolated from the thermal conductivity and heat capacity. The compositional dependence of thermophysical properties was interpreted according to the structure in short-range and intermediate-range order. Based on the Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and 11 B magic-angle spinning nuclear magnetic resonance (MAS-NMR) spectra, modifier cation with higher field strength prefers the formation of non-bridging oxygens (NBOs) for the charge compensation at high BO 1.5 / M O ratios. A lower amount of covalent bond and greater isolation of large borate groups lead to a lower thermal conductivity in calcium borate melt compared with strontium and barium borates. But the large size of Ba 2+ encounters difficulty in fitting around B [4] -O-B [4] linkages inside the overcrowded large borate groups when BO 1.5 /BaO = 2.5, promoting the formation of NBOs on the edge of borate groups for the charge compensation of modifier cations and leading to the decline in the thermal conductivity. Thermal conductivity plays a major role in regulating the thermal diffusivity at a given temperature since the compositional dependence of volumetric heat capacity is relatively weak compared with that of thermal conductivity.

Exploration of modifier based structural and spectroscopic traits of Eu3+ doped boro-tellurite glasses for solar UV photons converting applications

A new series of stable host glass with different modifier cations have been formed with the molar composition15XO + 39B2O3 + 25TeO2 + 10Na2O + 10K2O + 1Eu2O3 (X = Li2, Ca, Sr, Ba, Zn) through traditional glass preparation technique of melt quenching. The effect caused by the incorporation of modifier cations on the radiative assets of Eu3+ ions in the present host glass were inspected through X-ray Diffraction (XRD), Fourier Transformed Infra-Red (FTIR), UV–vis-NIR, photoluminescence and luminescence decay spectral studies at room temperature. The broad diffraction band in the XRD pattern confirms glassy or amorphous nature of the synthesized samples. The functional modes of vibration and structural modules in the prepared glass samples were inspected through FTIR spectra. The 4f − 4f electronic transitions pertaining to the trivalent europium (Eu3+) ions in the new host glasses were scrutinized by UV–vis-NIR absorption studies where in the dominant covalent bonding nature of the Eu3+ ions with its nearby ligands have been confirmed via average nephelauxetic ratio (β) and bonding parameter(δ) values. Optical bandgap (indirect and direct) values were testified to identify the photon energy transparent window and to explore the tendency of the formation of non-bridging oxygens. Luminescence ability of the prepared samples was inspected by exciting at a wavelength of 465 nm. Among the prepared samples, Eu3+ ions emissions were observed and the highest intensity of emission occurred at 612 nm (5D0→7F2) for BTLi:Eu glass. The Judd-Ofelt parameters were estimated and used to evaluate the radiative parameters such as radiative lifetime (τrad), transition probability (A), branching ratio (βR), stimulated emission cross-section (σPE) of all the emissions observed in the produced glasses and the outcomes were equated with the related literature. The colour chromaticity coordinates and colour correlated temperature (CCT) were explored from the emission spectra using CIE 1931 diagram and the CCT values found to lie in the range of 2000–4000 K. The luminescence decay comfortably fitted to the single exponential decay profile which further confirms the non-appearance of energy transfer via mutual interaction amongst Eu3+ ions in all the present glasses. All the observed results indicate the fact that the incorporation of Li+ cations induces more attractive radiative features with 77 % of UV to visible quantum converting efficiency than all other cations used in this contemporary study and among the prepared glasses, BTLi:Eu glass exhibits a better capability in red light emitting electro-optical applications.

Structure‐terahertz property relationship in sodium borosilicate glasses

AbstractWe report, for the first time, an early evidence of structure‐terahertz (THz) property relationship for two tie‐lines within the sodium borosilicate glass system. The NaBSi series was chosen to study the effect of the substitution of silicon dioxide for boron oxide, whereas the BNaSi series studies the substitution of silicon dioxide for sodium oxide. Nuclear magnetic resonance, infrared absorption, and Raman spectroscopies were used to determine structural changes across both series. THz time‐domain spectroscopy was used to record the refractive index over the measured bandwidth. Individual measurements at .502 THz were used as a frequency of focus for comparisons. The foundation for the proposed structure‐THz property relationship is based on higher measurable THz refractive index changes correlated to a depolymerized glass network, R > .5, a network consisting of SiO4 tetrahedra and charge‐deficient [BØ4]− tetrahedra‐forming borosilicate danburite and reedmergnerite rings with mixed Si–O–B bridges, and the formation of nonbridging oxygen (nbO) atoms on silicate tetrahedra. A polymerized glass network, R < .5, consists of homonuclear boroxol and silica rings within sodium borate and silicate subnetworks. Calculated and experimental fractions of tetrahedral borate and silicate tetrahedra with one nbO, optical basicity, density, and network connectivity data support the structure‐THz property relationship.

Enhanced near-infrared femtosecond nonlinear optical properties in zinc borate glasses activated with Er2O3

Several advanced materials have been investigated for nonlinear optical device applications. However, oxide glasses are competing materials in contrast to those advanced materials due to ease of preparation in three dimensions with diverse shapes along with flexibility in choosing the composition which is essential to tune the nonlinear optical features for specific applications. Doping rare-earth ions is one of the methods used to tune the nonlinear optical features of glass specimens, and it has been explored extensively in recent years. Using femtosecond laser pulses, the effect of Er2O3 concentration on nonlinear optical characteristics such as nonlinear absorption, nonlinear refraction, and optical limiting qualities was investigated using the Z-scan approach. The dual photon absorption and self‒focusing refraction nonlinear magnitudes are improved as the function of Er2O3 content owing to the formation of non‒bridging oxygens and enhancement in polarizability of glasses while the optical limiting features were decreased. These nonlinear absorptions and optical limiting results endorse the high Er2O3 loaded glasses are beneficial for nonlinear photonic devices functioning in the near-infrared regions.

Sm3+ ions doped Sm2Si2O7-based glass ceramics: Crystallization, luminescence and energy transfer process through heat treatment

Sm3+ ions incorporated Sm2Si2O7 crystalline phase formed in the aluminoborosilicate glass matrix synthesized via melting quenching technique followed by heat-treatment process is reported herewith. The preliminary confirmation on the obtained glass ceramics was made through X-ray diffration (XRD) studies. Formation of non-bridging oxygens (NBOs) in the glass network and the modes of vibrations of network units were analyzed through Fourier transform infrared spectroscopy (FTIR) studies. Surface morphology of heat-treated samples at varying temperatures was determined via a field emission scanning electron microscope (FESEM). The absorption studies on heat-treated samples signify the low bandgap values and high Urbach energy values due to improved crystallinity in the glass network. Judd–Ofelt intensity parameters identified for visible absorption transitions follow the trend of Ω4 >Ω2>Ω6. Excitation and emission studies on heat-treated samples show improvement in their intensities compared to the unheated base glass. The thermal quenching is observed at higher temperatures (540 and 580 °C for 3 h) of heat-treated samples. Calculations based on luminescence spectra including radiative transition probability, stimulated emission cross-section and branching ratio show good results for glass ceramics prior to precursor glass. Longer lifetimes of Sm3+ ions (milliseconds) in the level 4G5/2 are seen for glass ceramics. Color coordinates suggest the reddish-orange emissions from prepared glass ceramics. Thus, Sm3+ doped Sm2Si2O7 glass ceramics are favorable materials for solid-state lighting and laser applications.

Structural, physical and optical properties of ZnO-V2O5-P2O5 glass system

ZnO-V2O5-P2O5 glasses were synthesized by the melt-quenching technique. Fourier transformed infrared spectra reveal unshared vanadium-oxygen bonds, resulting in an increase in non-bridging oxygen bonds in the glass network. The densities of the samples were decreased from 3.112 to 2.240 g.cm−3, while the molar volumes were increased from 37.827 to 54.349 cm3.mol−1. The optical band gap of the base glass is determined to be 2.492 eV and this value was reduced to be 1.919 eV at the maximum addition of V2O5 content. The refractive index values were found to grow as the vanadium content rose. Both the optical band gap and refractive index values were discussed in the view of non-bridging oxygen formation within the glass matrix. Oxideion polarizability and interaction parameter were investigated for the glass samples.Theoretical optical basicity values of the investigated glasses were found to range between 0.399 and 0.407, indicating the tendency of oxide ionsto donate electrons to cations. The prepared glasses have high values of the optical basicity (1.077–1.267), third order non-linear optical susceptibility (0.625–1.364×10−11 esu), electronic oxide ion polarizability (2.816–4.143 Å3), and metallization criterion (0.353–0.310), implying that they can be used in non-linear optical applications.

Orange-reddish photoluminescence enhancement and wollastonite nanocrystals formation induced by CaO in Sm3+-doped calcium sodium borosilicate glasses

The influence of CaO content on the structural, chemical, and optical properties of Sm3+-doped calcium sodium borosilicate glasses is presented. Different undoped and Sm3+-doped borosilicate glasses with varying CaO (0–30 mol%) and Sm2O3 (0–4 mol%) contents were synthesized using the melt-quenching technique at 1300–1400 °C. Although XRD results showed the amorphous nature of all the glasses, HRTEM analysis revealed the formation of small wollastonite nanocrystals with sizes in the range of 10–25 nm for 30 mol% of CaO. FTIR and XPS analyses indicated the occurrence of the boric anomaly in glasses with 0–10 mol% CaO contents, causing an increase in the [BO4]- units and a decrease in [BO3] units. The high-resolution O 1s and Si 2p XPS spectra, studied as a function of increased CaO content, revealed the continuous formation of non-bridging oxygens that increased the glass structure's asymmetry and promoted the formation of interstitials used as host for Sm3+ ions. Consequently, PL intensity of Sm3+-doped borosilicate glasses increased with the addition of CaO, reaching a maximum at 30 mol%. Besides, the optimization of Sm2O3 doping concentration produced the highest intensity at 0.25 mol% with orange-reddish emission (CIE coordinates: x = 0.60, y = 0.40). These glasses have potential applications as n-UV and blue-excited LED-driven orange-reddish phosphors in white solid-state lighting devices and color displays.

Towards highly transparent tungsten zinc sodium borate glasses for radiation shielding purposes

The impact of tungsten oxide (WO3) additions on the structure, some physical and radiation shielding parameters of sodium zinc borate glasses have been scrutinized. These glasses were properly produced by the melt quenching method. The amorphous state was affirmed by X-ray diffraction (XRD) data. The internal structure within the short-range order of the glassy network was studied by the method of infrared spectroscopy (IR). The results of IR showed that the BO4 units are transformed to BO3 accompanied by the formation of nonbridging oxygens with further WO3 doping. This transformation of BO4 to BO3 and nonbridging oxygens is employed to explain the increase in the molar volume values with changing WO3/ZnO amount. Further, the optical transmittance was measured within the visible range to assure the transparency of the prepared glasses. The transmittance results confirm the absence of W5+, W4+, W3+ states; based on the absence of their absorption bands. Also, the transmittance results indicate that the only oxidation state in the present glasses is hexavalent tungsten (W6+). Additionally, the parameters of radiation protection of the manufactured glasses were investigated. It was found that, the addition of WO3 improves not only the radiation protection parameters (such as the linear attenuation coefficient) but also the transparency of the prepared glasses. Finally, we concluded that, the addition of WO3 to the glass samples leads to transparent glasses with an improved shielding ability at low energies but effects slightly at high energies. Due to the high transparency and the increased values of the linear attenuation coefficient of the prepared glasses, they are considered promising glasses in the field of nuclear radiation protection, especially at low energies.

Use of colemanite and borax penta-hydrate in soda lime silicate glass melting - A strategy to reduce energy consumption and improve glass properties

In view of recent energy crisis and environmental considerations, reductions of melting temperature and CO2 emissions during the production of commercial soda lime silicate (SLS) glass at industrial scale are major intentions. Here we show that this goal can be achieved by using carbonate-free borate minerals such as colemanite (Ca2B6O11·5H2O) and borax penta-hydrate (BPH, Na2B4O7·5H2O) as alternative sources for CaO and Na2O, respectively. The SLS glass melting temperature has decreased successively by the incorporation of B2O3 with substitution of equivalent wt% SiO2 resulting from gradual utilization of colemanite and BPH. Hot Stage Microscopy (HSM) revealed that the melting temperature was decreased from 1650 °C, for the parent commercial SLS glass, to 1528 °C on use of colemanite and further down to 1072 °C on utilization of both colemanite and appropriate quantity of BPH up to which the properties of the pristine glass can be retained. Thus, energy consumption equivalent to reduction in melting temperature could be minimized during the glass production. Another important environmental benefit achieved by using carbonate free minerals is significant reduction (12%) of CO2 emissions during thermal decomposition in glass melting which could minimize greenhouse gas to the atmosphere at a great extent. Further, the addition of colemanite improved micro-hardness, elastic modulus and thermal properties of the pristine glass through polymerization of glass network structure. In contrast to the use of BPH as a source of more than 8 wt% Na2O deteriorated glass properties with the formation of non-bridging oxygens into the glass network.

Physical, structural and optical characterization of silica-borotellurite glasses containing vanadium and nickel ions

Silica borotellurite glasses with compositions SiO2][SiO2][SiO2]0.2}0.99{V2O5}0.01]1-z (Ni0)z (where z = 0.005,0.010,0.015,0.020 and 0.025 M fraction) had been prepared by conventional melt quenching technique. X-Ray Diffractograms spectra confirm the amorphous nature of the prepared glasses. Study of infrared (IR) spectroscopy reveals an increase in the formation of nonbridging oxygens (NBOs) as nickel concentration increases. This resulted in the decrease of density and oxygen packing density (OPD) of the glass. The observed ESR spectra confirmed that V4+ ions exist as vanadyl ion in the octahedral coordination with tetragonal compression. Based on UV–vis absorption spectra, four absorption bands have been observed with indirect optical band gap, Urbach's energy, refractive index and other optical parameters have been calculated. The Ni2+ ions were distributed with octahedral and tetrahedral coordination of the ligand field. Nevertheless, the octahedral coordination of Ni2+ dominated over tetrahedral coordination with the increase of NiO concentration consequently, confirmed the increase in NBOs from the IR spectra. These observations reflect the decrease in optical band gap, metallization criterion and the increase in Urbach's energy and refractive index.